The majority of cancers occur among those over the age of 50. However, in recent years, researchers around the world including the UK, US, Australia and parts of Europe have reported a shift where more cancers are being diagnosed in people under 50. These are commonly referred to as ‘early-onset’ cancers.  

This doesn’t mean cancer is suddenly common in young people. Age is still the most important risk factor for cancer overall. Although the average age of diagnosis for cancer overall differs by country, the median or average age of diagnosis in developed countries is above the age of 60. Average age at diagnosis also differs by where in the body the cancer develops, which is commonly referred to as ‘cancer site’ or ‘site-specific cancer’. 

At the same time, evidence suggests that more new cases are being diagnosed among those younger than 50 for several site-specific cancers. Furthermore, incidence rates are higher among this group now compared with those who were in the same age group in previous decades. In short, we are seeing increasing numbers of some cancers among younger people.

To understand why this might be happening, World Cancer Research Fund International analysed how the absolute numbers of 12 site-specific cancers changed between 2000 and 2023 in the United States and the Netherlands, and 2001 and 2023 in England among those under 50 years of age. For each country, we also explored incidence rates for the first and last years – 2000 and 2023 for the US and Netherlands and 2001 and 2023 for England – for each site-specific cancer. Finally, we reviewed the published evidence related to what might be driving changes in the number of cases of cancer in the last few decades.   

There have long remained questions, and indeed misconceptions, around the relationship between soy foods and cancer.  

Soy foods, which include tofu, soy milk and other soy-based products are frequently used in traditional Asian diets and eaten throughout life.   

Recent research funded by World Cancer Research Fund has found that intake of soy products during childhood and adolescence is associated with lower mammographic density (also known as breast density) in adulthood. Mammographic density – the proportion of dense breast tissue seen on a mammogram is a well-established predictor of breast cancer risk.  

The study, led by Professor Suzanne Ho at The Chinese University of Hong Kong and published in the journal Nutrients, assessed the lifetime soy intake of 815 healthy premenopausal women aged 35-45 in Hong Kong across different life stages, including childhood, adolescence, young adulthood and recent intake.  

It found that women with consistently high soy intake during early-life had approximately 6% lower breast density than those with consistently low early-life intake.  

The Chinese University of Hong Kong’s Emeritus Professor Suzanne Ho said:  

“Our findings suggest that soy consumption earlier in life, particularly during childhood and adolescence, is associated with lower breast density in adulthood. As we did not see the same association for recent soy intake, it points to early-life exposure as a potentially important window for breast tissue development in later life. 

“Soy is a common component of traditional Asian diets, and this study adds to evidence suggesting that the timing of exposure to soy foods may matter. More research is needed to confirm these findings and to understand whether modifying early-life soy intake could contribute to breast cancer prevention.” 

Soy consumption and life stage 

The results suggest that soy exposure early in life may influence adult breast tissue composition and provide long-term protective effects that could help reduce breast cancer risk. It follows growing evidence suggesting that the stage of life that soy is consumed may be as important as how much is consumed.  

In particular, it is thought that soy consumption during early-life may have a strong influence on later breast cancer risk by affecting mammary gland development. However, evidence linking soy intake at specific life stages to adult breast density has remained limited. 

As well as taking mammograms, the research team assessed soy consumption using a validated soy food frequency questionnaire covering 32 soy products. Participants reported their current intake and recalled their intake during childhood, adolescence and young adulthood, supported by life-history prompts. 

After adjusting for confounding factors including age, waist circumference, and physical activity, the researchers found that soy protein intake during adolescence and childhood was significantly and inversely associated with adult breast density. In contrast, recent soy intake was not associated with breast density. 

World Cancer Research Fund International Hong Kong Ambassador, Professor Anne Lee said:  

“The finding that women who ate more soy during childhood and adolescence had lower breast density as adults is especially interesting. It supports the idea that diet during early development may have a lasting effect on breast tissue.

“This study provides useful observational evidence for the idea of “early-life nutritional programming” and highlights the possibility that diet early in life could play a role in reducing breast cancer risk. Furthermore, the use of a Life History Calendar (LHC) with audiovisual aids to enhance the recall of distant dietary habits is a notable methodological innovation.” 

The authors emphasise that the study is observational and based on self-reported information. Further studies would help to validate if soy intake directly contributes to the lowering effects on breast density or reduces breast cancer risk. 

What are the potential mechanisms?  

Soy foods contain isoflavones, bioactive compounds that can interact with oestrogen-related pathways. The findings add to growing evidence that the timing of dietary exposure may be important, with childhood and adolescence representing a key developmental window where the mammary gland undergoes rapid structural and hormonal changes which could influence cancer susceptibility.  

World Cancer Research Fund International Executive Director of Research and Policy, Dr Giota Mitrou said: 

“While characteristics such as overweight and obesity are well established factors linked to breast cancer risk, only a limited number of studies have evaluated the association between soy intake and breast density, and so far, findings remain inconclusive. 

“This study adds to our understanding of how exposures across the life course may shape cancer risk, which is a key area of work for World Cancer Research Fund. It raises the possibility that breast tissue may be particularly susceptible to dietary influences during specific developmental windows and highlights the need for further research into dietary patterns in different population groups.”  

During one of the most special times in her life, paramedic Sarah Husband was diagnosed with HER2-positive breast cancer in October 2024.

Two years on, she shares her story as part of World Cancer Research Fund’s 112 Skips a Day in October challenge, which is fundraising for new treatments and improved advice and support for breast cancer patients.

Throughout her pregnancy, Sarah experienced breathlessness, chest discomfort and extreme fatigue alongside intermittent burning pain over a lump in her right breast – which she discovered at around six months pregnant.

Initially believing that her symptoms were pregnancy-related breast changes or a blocked milk duct, Sarah followed the advice she was given and tried warm compresses, but the lump did not go away.

Sarah explained:

“As time passed, I developed a sinking feeling that it may be something more serious, which prompted me to seek further investigation.”

After a biopsy in her third trimester, Sarah received her breast cancer diagnosis just one week after the birth of her son, Ted.

“I should have been soaking up those precious newborn moments, but the joy of becoming a mum again was suddenly overshadowed by fear.”

Her treatment began with six rounds of pre-operative chemotherapy, which shrunk the tumour “dramatically” but did not leave Sarah cancer-free.

“There were days I felt exhausted, sick and frightened, but motherhood doesn’t stop because you have cancer. My boys gave me a reason to keep putting one foot in front of the other.”

Further treatment included a skin-sparing mastectomy and lymph node removal, together with a tissue expander to begin the long journey towards breast reconstruction.

“As a paramedic, I was used to caring for others, but overnight I became the patient. My focus shifted from looking after people in their darkest moments to wondering whether I would live long enough to watch my own children grow up.”

Her treatment concluded with 14 rounds of post-operative chemotherapy and five high-dose radiotherapy treatments, followed by a targeted drug to reduce the risk of her cancer returning.

Alongside the side effects of treatment, Sarah describes her inability to breastfeed as one of the “quiet heartbreaks” that stays with her today.

“Like so many mothers, I imagined feeding my baby, comforting him and creating that bond. Instead, cancer took the choice away before I even had the chance. I remember crying for several nights as my milk came in and gradually dried up, knowing I could no longer feed my newborn.”

Today, Sarah’s scans are showing no evidence of disease (NED), which she credits to decades of research and the generosity of people who fundraise for it.

“Cancer research gives me hope. Every breakthrough represents another family who may have more birthdays together, more first days at school and more cuddles.”

Since her diagnosis, Sarah has made mindful changes to her diet, such as eating a wider variety of fruit and vegetables to support her health and help protect against weight gain, overweight and obesity – which are linked to at least 13 types of cancer.

“After experiencing something over which I have such little control, making thoughtful changes helps me feel like I’m doing everything in my power to support my recovery.”

Evidence from World Cancer Research Fund suggests that physical activity can help reduce risk of three common cancers: colon, post-menopausal breast cancer and womb cancer.

By signing up to 112 Skips a Day in October, you can help mothers like Sarah create more memories with their children and take steps to reduce your own cancer risk.

Cancer is an extremely complex disease, with over 200 different types. Even tumours belonging to the same cancer type can have important biological differences. Tumour heterogeneity refers to the differences observed between tumours of the same type in different patients.

For example, colon cancers are not all biologically the same. They can be grouped into molecular subtypes that may behave differently and respond differently to their surroundings.

Research funded by Wereld Kanker Onderzoek Fonds (WKOF) – the Netherlands-based charity within the World Cancer Research Fund network of charities – explored whether colon cancer recurrence differed between tumour subtypes and whether diet and other lifestyle factors at diagnosis were associated with recurrence.

The new study, published recently in the journal Cancer Epidemiology, suggests that people with a particular tumour subtype – the imCMS4 subtype – had a significantly higher risk of cancer recurrence.

The results also found that, among people with imCMS4 tumours, a more pro-inflammatory diet around the time of diagnosis was associated with a higher rate of recurrence. However, this association was not seen in other subtypes.

Dr Evertine Wesselink, based at the Netherlands Cancer Institute and lead author of the research, said:

“When we talk about lifestyle habits, such as diet, physical activity, and body weight, and cancer, we often look at the big picture. But tumours are incredibly diverse. We wanted to explore whether a person’s diet is associated with their risk of cancer recurrence differently depending on the specific ‘molecular personality’ of their tumour”.

Colorectal cancer subtypes

To capture some of the biological variation seen between colon cancer tumours, researchers classify colorectal tumours (meaning both colon and rectal tumours) according to their molecular, cellular and surrounding tissue characteristics. One widely used framework is the four Consensus Molecular Subtypes, or CMS.

 For this research, tumours were grouped into four main subtypes:

• CMS1: These tumours show strong immune-system activity and often contain many immune cells. They commonly have defects in the system that usually repairs DNA which can lead to the accumulation of genetic changes.
• CMS2: This is the most common subtype. These tumours are mainly driven by well-known cancer growth pathways and tend to have less immune activity around them.
• CMS3: These tumours have distinctive changes in how cancer cells process energy and nutrients and have relatively little immune activity.
• CMS4: These tumours have a strong supporting tissue and display inflammation-related and immune-suppressive characteristics. They also tend to have a greater potential to spread and are generally associated with poorer outcomes.

Previous studies have highlighted the value of CMS as a prognostic marker in colorectal cancer, but the association between CMS and cancer recurrence, and whether the inflammatory potential of diet and lifestyle relates to recurrence differently across colon cancer subtypes, is not well understood.

Looking at tumours under the microscope

The researchers studied people with stage I–III colon cancer from two large Dutch patient cohorts. They compared 167 people whose cancer recurred with 668 people whose cancer had not returned by the same point in follow-up.

They used artificial intelligence to analyse routine microscope images of tumour tissue from 532 patients and assign each tumour to an image-based molecular subtype, known as imCMS1, imCMS2, imCMS3 or imCMS4.

Dr Evertine Wesselink said:

“The subtype was identified from standard tumour slides using artificial intelligence. Because these slides are already widely collected in hospitals, this approach could eventually offer a relatively quick and scalable way to classify tumours.”

Participants also completed questionnaires about their diet, physical activity, smoking, alcohol use and body weight in the month preceding their diagnosis. These were used to generate:

• A dietary inflammation score, where a higher score meant a more pro-inflammatory diet.
• A lifestyle inflammation score (which took into account physical activity, smoking status, BMI and alcohol consumption), where a higher score meant a more pro-inflammatory lifestyle.

Next, the research team examined whether tumour subtype, diet and lifestyle were associated with the risk of recurrence.

What did the results show?

Their analysis found that people with an imCMS4 tumour had more than twice the risk of recurrence compared with those with the most common subtype, imCMS2.

Across all patients combined, the inflammatory potential of the diet was not clearly associated with recurrence. However, the picture changed when the researchers looked separately at each tumour subtype. Among people with imCMS4 tumours, each one-unit increase in the dietary inflammation score was associated with a 39% higher risk of recurrence, but no clear association was seen in the other subtypes.

Within the imCMS4 group, higher intakes of tomatoes, apples and berries, fish and nuts were each associated with a lower risk of recurrence. However, the research team stress that these findings were exploratory, based on a relatively small subgroup, and do not prove that these foods themselves prevented recurrence.

A more pro-inflammatory lifestyle showed a possible association with higher recurrence risk overall, but this finding was not statistically clear. The researchers found no clear association between the lifestyle inflammation score and risk of recurrence across different tumour subgroups.

World Cancer Research Fund International Assistant Director of Research and Policy , Dr Helen Croker, said:

“The study suggests that the biological subtype of a colon tumour may help identify people at greater risk of recurrence and that diet may play a role.

“It is wonderful to see early-career researchers produce such interesting results as part of our INSPIRE research challenge. These findings raise the possibility that diet could be especially important for certain patients, particularly those with imCMS4 tumours.”

Dr Evertine Wesselink added:

“As our study was observational, relied on self-reported diet and lifestyle, and included relatively small numbers once patients were divided into subgroups, the results should be repeated in other populations and tested in studies that follow dietary changes after diagnosis.”

The relationship between dairy consumption and breast cancer risk has raised questions for scientists for years, with various studies reporting differing results. Recent work has begun to explore whether these inconsistent findings could be explained by the degree of food processing.

Although nutritional composition (such as the amount of calcium, fat, vitamin D or hormones in a product) has traditionally been considered the primary factor for explaining these inconsistent results, emerging laboratory and food chemistry research suggests that processing methods may also influence the biological properties of dairy foods.

A new review paper, published recently in the journal Advances in Nutrition, led by researchers at the University of Toulouse, aims to move the research beyond a nutrient-only explanation for the differences in association and asks whether food-processing chemistry should be built into future study designs.

Dr Silia Ayadi, first author on the paper, has been funded by the Wereld Kanker Onderzoek Fonds, (WKOF) – the Netherlands-based charity within the World Cancer Research Fund network of charities.

Dr Silia Ayadi, Ph.D., said:

“Through this work we have proposed a novel hypothesis linking the processing of dairy products to the formation of molecules that may influence breast cancer-related pathways.

“By combining research from nutritional epidemiology, food chemistry, and molecular mechanisms, this review paper provides a new potential perspective for explaining the differences we see in the existing research that has examined the dairy and breast cancer association.”

What does the evidence say so far?

When exploring how diet and nutrition can impact cancer risk, dairy products have received considerable attention due to their complex composition, which includes macronutrients, hormones, and a wide range of bioactive lipids. Bioactive lipids are compounds that regulate biological processes within the body, such as inflammation or cell growth.

To date, studies examining a possible link between dairy consumption and breast cancer have found inconsistent results, with reports of neutral, inverse, or positive associations depending on the population, tumour type, and type of dairy product consumed.

Milk, fermented products, cheeses, and highly processed dairy foods differ not only in fat content and fermentation status, but also in their exposure to technological processes such as heating, drying, and storage. Recent laboratory research suggests that these processing methods can generate a wide range of bioactive molecules beyond conventional nutrients, some of which may affect biological pathways, even at very low levels.

Proposing a new framework

To dig further into the existing literature, the authors integrated findings from 82 publications covering three areas of research – studies on dairy consumption and breast cancer, research on food chemistry, and lab studies on how these changes might affect cancer-related pathways.

A central hypothesis is that processing dairy products can generate or modify bioactive fat-derived molecules, including oxidised forms of cholesterol. In experimental models, some of these compounds can influence biological pathways relevant to breast cancer, including inflammation and hormone signalling. The review also notes that fermentation may generate metabolites with potentially different, possibly protective, biological effects.

This work proposes an original framework suggesting that dairy processing, not only nutrient composition, may help explain the differing results seen in this area of breast cancer research. The team highlights that the evidence is mainly from laboratory and mechanistic and epidemiological research and is not sufficient to draw conclusions about cause and effect, or steer clinical advice.

Dr Marc Poirot, Ph.D., Research Director at Inserm, said:

“Different dairy products, including milk, cheese, yoghurt, butter, fermented products and ultra-processed dairy foods, undergo different forms of heating, fermentation, storage and industrial processing, which may change their molecular composition.

“By integrating nutritional epidemiology, food chemistry, and molecular biology, this work offers a novel angle to explain the differences in the associations observed across dairy products and cancer outcomes.”

World Cancer Research Fund International Assistant Director of Policy and Research Dr Helen Croker, said:

“The WCRF network’s evidence syntheses have shown suggestive protective effects of dairy foods and high calcium diets, but the findings are not conclusive. The current work outlines the heterogeneity of dairy foods, including the level of processing, and may help to explain previous inconclusive findings.

“The focus on processing is interesting and in line with emerging research on ultra-processed foods. This represents a promising avenue for advancing our understanding of how processing of dairy foods could influence the development of cancer.”

Knowing how to prevent cancer is only half the battle. Making sure that knowledge actually works in real schools, clinics and hospitals is the other half – and that’s exactly what three newly funded research projects are now setting out to test.

This is important work. About four in ten cancer cases could be prevented, yet proven prevention methods – from HPV vaccination to stop-smoking support – don’t always reach the people who could benefit from them most.

Closing that gap is the aim of Reimagining Cancer Research in Europe, an initiative bringing together cancer charities and researchers from across the continent, coordinated through our long-standing partnership with the Union for International Cancer Control (UICC).

At World Cancer Research Fund International and our network partner Wereld Kanker Onderzoek Fonds (WKOF), we are proud to be supporters of this initiative – both as co-funders and members of its steering committee.

Rather than searching for new scientific discoveries, this programme funds what’s known as “implementation research” – studying the best ways to get prevention methods that already work adopted into everyday healthcare, in support of Europe’s Beating Cancer Plan and Europe’s Mission on Cancer.

In this latest funding round, three international research collaborations have been awarded a combined €1.49 million to test new approaches over the next two years:

• Preventing tobacco and vaping in schools (FRESHAIR4Schools) – researchers in the Netherlands and Poland are adapting a WHO-aligned tobacco- and nicotine-free school policy, a youth vaping-prevention programme and an eHealth quit-support tool for use in Polish secondary schools. The aim is to help protect young people from a habit that remains one of the biggest drivers of preventable cancer.
• Reaching women in wartime Ukraine (HPV-FASTER) – a team spanning France, Ukraine and the UK is testing whether combining HPV self-sampling, vaccination and counselling can help more women access cervical cancer screening and prevention, even in conflict-affected regions.
• Preventing ovarian cancer through simple surgery (STOPOVCA-Europe) – researchers in the Netherlands and Romania are working to roll out a proven Dutch approach – removing the fallopian tubes during other planned surgery, known as opportunistic salpingectomy – to help prevent ovarian cancer more widely across Europe.

These are still early days. Each project has up to two years to test and refine its approach.

Research Translation Manager at World Cancer Research Fund International,
Dr Vanessa Gordon-Dseagu, said:

“Nearly four in ten cancers could be prevented. That’s the opportunity UICC’s newly funded international research collaborations are seizing. The three projects are pushing forward our understanding of how to stop cancer before it starts, from tackling tobacco use to preventing cervical and ovarian cancers.

“By finding better ways to prevent, detect and diagnose cancer early, this work will help life-saving interventions reach more people, more consistently, to improve the health of communities across Europe and beyond.”

World Cancer Research Fund has been a partner of UICC for many years. Our partnership includes collaboration on scientific papers, global advocacy on cancer – including contributing to WHO statements and membership of the UICC global advocacy advisory group – and participation in the UICC World Cancer Leaders’ Summit and World Cancer Congress. We’re also members of the UICC Cancer Prevention Network, contribute to the International Cancer Control Partnership portal and support UICC’s World Cancer Day.

Co-funders: This initiative is co-funded by World Cancer Research Fund International, Wereld Kanker Onderzoek Fonds (WKOF), the Dutch Cancer Society (KWF), the Swedish Cancer Society (Cancerfonden) and the Danish Cancer Society, with scientific input from the International Agency for Research on Cancer (IARC, part of the World Health Organization). 

When her sister found a lump in her breast, Meera decided to get one of her own checked, which helped save her life. Now, she urges people to fundraise for research that could save others.

Meera is sharing her story in support of our fundraising for research into targeted treatments and improved advice and support for breast cancer patients.

While juggling life with two small children, Meera discovered a lump in her left breast which she believed was a blocked milk duct.

Meera said:

“I breastfed my son from birth. During this time, I noticed many lumps and bumps, so I just ignored it. Like lots of mums with young children, I didn’t think about my own health or prioritise it.”

Months later, Meera’s sister found a lump in her own breast. After being checked and receiving the all-clear, Meera began to think differently about her symptoms.

Following a GP visit, Meera was sent for further tests. After scans and a biopsy, she was diagnosed with hormone receptor-positive (HR+) breast cancer in March 2025.

“It’s a reminder of why it’s so important to have these conversations with loved ones. My sister sharing her experience with me effectively saved my life.”

Her treatment involved sixteen rounds of chemotherapy over five months, followed by surgery and twenty rounds of radiotherapy. Reflecting on her diagnosis and treatment, Meera shared:

“It was heartbreaking and a huge shock. My biggest fear was not being around to see my children grow up.”

Now in remission, Meera prioritises exercise to support her recovery, visiting the gym at least three times per week to improve her strength and fitness.

“My gym has a machine that calculates your body composition and carries out a strength test to help you lift heavier weights over time. 

“When I first took a strength test in January, after nearly a year of cancer treatment, I had the strength of a 73-year-old. My latest test showed that I now have the strength of a 25-year-old! Seeing this transformation has been incredible, as exercise has become a huge part of my life post-treatment.”

Recently, a study we funded showed that following evidence-based lifestyle recommendations can support long-term health after a cancer diagnosis.

Regular physical activity can also help people maintain a healthy weight, and having less excess body fat can reduce risk of several cancers.

Rachael Hutson, World Cancer Research Fund’s CEO, commented:

“We are incredibly grateful to Meera for sharing her experience, which shows how research into breast cancer treatments is changing lives and why it is needed now more than ever. We’re proud to be funding pioneering research at the University of Southampton, which is bringing us one step closer to kinder, more effective treatments for breast cancer patients.”

Supporting breast cancer research is important to Meera after she benefitted from ribociclib, a form of targeted therapy, following its introduction for primary breast cancer patients in February 2021.

“Research makes change happen. My biggest fear is dying while my children are young, and every breakthrough brings me closer to a future where that fear doesn’t become reality. People who fundraise may never meet the people they’re helping, but they give families like mine something priceless: hope and more time together.”

By signing up to one of our challenge events, you can offer the gift of hope to people like Meera.

Twenty years ago, researchers in Mexico set out to answer a question that could not be answered retrospectively: ‘How do lifestyle, reproductive and environmental factors shape women’s risk of cancer and other chronic diseases over time?’

“The only way to do that is to start off with a group of people who are free of the disease and wait until that disease occurs,” says Dr Martin Lajous, who directs the Mexican Teachers’ Cohort (MTC), now one of the largest long-term health studies in Latin America.

Since 2006, the MTC cohort has followed more than 115,000 women working in Mexico’s public education system, generating evidence on breast cancer, cardiometabolic disease, smoking, sugar-sweetened beverages, alcohol and other risk factors.

But building the cohort was only the first challenge. For years, the team worked to solve a persistent problem – how to identify new cancer cases in a country without a national cancer registry. The turning point came in 2019 when the problem was finally solved and, as Dr Lajous puts it, the MTC moved from being “a promise of a cancer cohort to a realisation of a cancer cohort”.

While there has been great change around the world, and in Mexico over the last 2 decades, from evolving technology to changing eating habits, collaboration has remained central to the mission of the MTC.

Long term partners

Funding to establish the Mexican Teachers’ Cohort began in 2006. Since then, the MTC has followed more than 115,000 women working in Mexico’s public education system. It generates evidence on breast cancer, heart disease, smoking, sugar-sweetened beverages, alcohol and other risk factors.

Collaboration has remained central to the mission of the MTC. “None of this would have been possible without AICR and WCRF, you believed in us,” says Dr Lajous. “And we are forever grateful for this sustained support.”

The partnership between the American Institute for Cancer Research, WCRF and MTC remains strong and ongoing. In 2020, AICR funded a grant for Dr Lajous to study lifestyle and breast cancer risk in a prospective study of Mexican women. In 2026, AICR funded a grant for Dr Lajous to study fibre, gut microbiome and colorectal cancer risk in a prospective study of Mexican women.

In May 2026, the WCRF International bursary helped Dr Lajous’ colleague Dr Liliana Gómez Flores Ramos, PhD, to attend the International Agency for Research on Cancer (IARC) conference in Lyon, France. At the IARC conference, she presented work on alcohol consumption and breast cancer from the MTC.

The story so far

The idea for the Mexican Teachers’ Cohort grew out of a 2004 case-control study on carbohydrates and breast cancer, led by Dr Isabel Romieu, Dr Walter Willett and Dr Mauricio Hernández. The study attracted wide attention, and inspired by international studies using teachers, sparked the idea for a prospective cohort based in Mexico.

Dr Lajous, who was based at the Harvard School of Public Health at the time, was invited to be part of the team setting up the project.

“We invited more than 115,000 women, working in the public education system in Mexico to provide us with details on their health conditions, but also on their lifestyle,” says Dr Lajous. “It was built with the intention of following up over time to be able to compare these lifestyle factors, or reproductive factors, in individuals who ended up having, for instance, breast cancer and those women who did not.”

From a promise to a realisation

ESMaestras researchers and operational staff at the Annual Liaison Meeting held on December 6, 2019, at the facilities of the Mexican Health Foundation (FUNSALUD).

When the cohort was first established, the program was able to collect baseline data. (such as age, menopause and smoking status, and BMI) and the participants have been completing questionnaires approximately every 4-6 years.

“But, in order to have a cancer cohort, you have to demonstrate that you can actually identify individuals who develop the disease,” says Dr Lajous. “And this element is what really took time to develop, making the primary challenge ascertaining incident cancer cases without a national cancer registry.”

By collaborating with different institutions in Mexico, the MTC were able to verify national IDs and have achieved approximately 97% ID coverage within the cohort. The national ID numbers then enabled cross-linkage with national mortality registries, cancer registries and health utilisation databases.

By 2019, they had developed a multi-source strategy to identify cancer cases using health utilisation databases (discharge data, consultations, medication use) from major healthcare providers.

“We dedicated three years to develop the method and convince the stakeholders, and to get everyone together, which took a lot of conviction, and then we finally got it done,” says Dr Lajous.“That’s when we went from being a promise of a cancer cohort to a realisation of a cancer cohort.”

Key milestones

An example of the questionnaire for participants, originally circulated by post.

Aside from officially becoming a cancer cohort in 2019, key milestones include findings that have had implications for prevention and public health policy.

Highlights include data on diabetes and weight gain that informed Mexico’s sugar-sweetened beverages tax. “Mexico has led efforts to change the dietary environment and reduce the consumption of sugar, sweetened beverages,” says Dr Lajous. “So, we conducted analysis on sugar-sweetened beverage intake and diabetes and also weight gain, which I think has been used by policy makers.”

The cohort has also produced some important work on smoking. “You may presume that we already know about the link between tobacco and cancer,” says Dr Lajous. “That may be so, but the pattern of tobacco smoking in Mexico, and particularly among women in Mexico, is one of occasional or very low consumption.

“There is a perception that if you only smoke a cigarette a week, it’s fine. However, we showed with the Mexican Teacher’s Cohort that even very low consumption of tobacco was associated with death.”

In recent years, external groups have begun seeking data from the MTC, shifting internal perception from a theoretical project to a strategic asset, something that Dr Lajous is proud of. “For the past 20 years, I’ve been reaching out to people to let them know how important the cohort is, how key this resource is, how they all should be proud of it. And now the dial has shifted, and institutions have started reaching out to us to collaborate, but it took time.”

Engagement and building trust

Teachers offered two advantages that made a long-term study feasible. Many were already used to completing written evaluations through an economic incentive programme, and their employment stability, healthcare access and pension system made it easier for researchers to remain in contact over many years. But the cohort’s longevity has depended on more than the suitability of teachers as a study population, it has also depended on trust.

“You must have a participant-centered approach, in the sense that if we promise something to the participants, be sure that you deliver that,” says Dr Lajous.

A key challenge for the team over time has been maintaining this engagement as teachers retire and communication has evolved from paper to electronic.

To ensure contact is kept consistent, the MTC plan monthly webinars, a well-attended series on health topics for all teachers, not just those who are part of the study. The team has also moved to home visits to collect data in-person for older, less tech-savvy participants. And, to ensure community building, created state-specific Facebook groups for participants.

Importantly, Dr Lajous stresses a two-way dialogue with the cohort. Feedback from teachers has helped shape the research agenda, leading to studies on stress and Adverse Childhood Experiences (ACEs). “One thing we’re always pushing for is that we keep our ears open to their concerns,” he says.

Lessons learned from the Mexican Teachers’ Cohort

Dr Martin Lajous speaking to the audience at the 20th anniversary event for the Mexican Teachers’ Cohort.

A lesson for Dr Lajous over the last 2 decades of setting up such a large-scale and long-term cohort is patience. “It’s a marathon in the sense that it requires consistency over time,” he says. “Understanding that this is a long-term investment and that you need to be patient. Sometimes things are not going great, but you just need to keep moving.”

People are at the heart of the project. Fostering a dedicated team and using international partnerships to build leverage and demonstrate value has been essential to the MTC. Dr Lajous also notes the importance of incorporating young investigators into the cohort and making them feel invested, so that the programme can be sustained over a long period of time.

“We are a relatively small team and collaboration with people outside of Mexico is important for us,” says Dr Lajous. “It gives us leverage in Mexico and also because it articulates that what we’re doing is important, and people elsewhere are seeing the value in the work that we’re doing.”

Future research

As the cohort enters its third decade, its research questions are changing with its participants.

“We want to understand the intersection between ageing, cognitive health, and cancer. So now we have a grant where we are going to visit 15,000-17,000 participants at their homes to perform in-depth cognitive assessments,” says Dr Lajous.

The team also plans to expand their work into environmental exposures including plastics, light at night, and climate-mediated events.

“And for me, the most salient cancer-related problem right now is colorectal cancer, which is increasing much more dramatically than other cancers. It’s currently the leading cause of cancer mortality in Mexico but we have very limited strategies for prevention and control of the disease.”

Reflecting on the last 20 years, Dr Lajous says, “I’m most proud of how this project has changed people’s lives and will potentially change a lot more people’s lives.”

Looking back, the cohort’s greatest achievement may be exactly what it set out to create – evidence rooted in real lives, sustained by trust, with the power to inform future generations on cancer prevention.

A new study has identified five proteins in the blood that may help explain why people who are naturally ‘morning people’ tend to have a lower risk of breast cancer than ‘evening people’.

This work, led by researchers at the University of Hong Kong, was funded by Wereld Kanker Onderzoek Fonds, (WKOF) – the Netherlands-based charity within the World Cancer Research Fund network of charities.

The findings, published in the journal Communications Medicine, do not mean people can lower their risk simply by getting up earlier. Chronotype – our natural leaning towards mornings or evenings – is largely set by our genes and is hard to change. Instead, the real value of this research lies in the proteins themselves, which could point scientists towards new ways to prevent or treat breast cancer.

What is chronotype, and why does it matter for cancer risk?

Chronotype describes whether someone is naturally more of a ‘morning person’ or an ‘evening person’. Earlier research has linked having an evening chronotype, and other disruptions to the body’s internal clock – such as shift work, jet lag or irregular sleep – to a higher risk of breast cancer. But exactly why this happens has not been clear, which has made it hard to know what, if anything, could be done about it.

How did the researchers investigate this?

To dig into the biology behind the link, the team used a method called Mendelian randomisation. This uses genetic information to help work out whether one thing – in this case, chronotype – actually influences another, such as breast cancer risk, rather than the two simply appearing together by chance.

The researchers drew on genetic and health data from more than 650,000 people who took part in two large studies, UK Biobank and 23andMe, all of whom had self-reported whether they saw themselves as more of a morning or evening person.

They then took a two-step approach. First, they looked for links between chronotype and levels of nearly 5,000 different proteins in the blood, and found 895 proteins connected to a morning chronotype. Second, they checked whether any of those proteins were also linked to breast cancer risk and at this point, seven stood out as promising candidates.

To avoid false leads, the team ran an additional check called colocalisation. This statistical test shows whether the same genetic signal is genuinely influencing both the protein level and breast cancer risk, rather than two separate signals sitting close together by coincidence.

Dr April Shan Luo, Research Assistant Professor at Li Ka Shing Faculty of Medicine, the University of Hong Kong, who led the study, said:

“This gap in our understanding is significant in light of the growing prevalence of sleep deprivation in modern society and the challenges of being able to change or alter chronotype, particularly due to external factors such as shift work and frequent travel.

“There is a real need to better understand the link we are seeing between chronotype and breast cancer risk.”

What did they find?

After all the checks, five proteins stood out as having a genuine role in linking morning chronotype to a lower risk of breast cancer:

• ADAM15
• BTN2A1
• CASP8
• PDCD6
• RSPO3

Some proteins were more strongly linked to particular types of breast cancer than others. PDCD6, for example, showed the strongest connection to a subtype known as luminal A-like breast cancer.

Dr Luo, a recipient of the INSPIRE research grant, aimed at early career investigators, said: “We used large genetic datasets to examine morning preference, blood protein levels, and breast cancer risk. We also looked at different breast cancer subtypes and used breast cancer tissue data to assess the biological relevance of the proteins.”

Why does this matter?

World Cancer Research Fund International’s Assistant Director of Research and Policy, Dr Helen Croker, said:

“We know that there is a potential link between breast cancer risk and sleep chronotype, but this research has helped move the dial on our understanding of the biology behind this association.

The genetic tendency to be a morning person appears to be connected to a set of molecular switches, and some of those switches may also be linked to breast cancer risk. These findings improve our understanding of how sleep-related behaviour may influence breast cancer risk and further research could influence prevention strategies.”

Because chronotype is largely determined by our genes, this research is not a call to change your sleep habits. Its real potential lies in the proteins themselves: each one could be a possible new target for future cancer-prevention drugs or treatments, though that work is still at an early stage.

The researchers also note that their data came from people of European ancestry, so more research is needed to see whether the same proteins matter for people from other backgrounds.

Today the Commons Health and Social Care Select Committee published a report on fixing the food environment as part of its food and weight management inquiry. Its message to Government is loud and clear: it is time to stand up to industry and move forward with a bold new approach to tackling obesity. 

Read the report (PDF).

The environments in which we live, work and shop play a major role in shaping our health, yet many people are surrounded by the promotion and availability of unhealthy food options. Addressing this is essential for cancer prevention – excess weight is a cause of at least 13 types of cancer and is the second biggest preventable cause of cancer in the UK after smoking. 

Many of the Committee’s recommendations are reflected in World Cancer Research Fund’s written evidence to the inquiry and, if implemented together, would help make the healthy choice the easy choice. In particular, we welcome the Committee’s recommendation that the healthy sales reporting policy should be introduced as soon as possible, with targets for major supermarkets set within the next 12 months and for the wider food industry by the end of Parliament. In practice, the policy would mean that large food businesses would be incentivised to have healthier products on their shelves and in promotions – leading to a potential reduction of obesity by around a fifth. We also strongly echo the Committee’s recommendation for the Government to exclude actors with a vested interest from discussions on the formation of policies on food, diet and obesity prevention.  

Overall, the report sets out a clear roadmap for fixing our broken food environment. As the UK prepares for a new Prime Minister, we urge them to demonstrate their commitment to prevention by taking forward these recommendations at pace. This is a vital opportunity to fix our food environment, tackle obesity and prevent cancer for future generations. 

During the week, we had more than 30 health professionals and experts backing the campaign, alongside organisations including the British Dietetic Association, the NIHR Cancer and Nutrition Collaboration, Patient Information Forum, International Agency for Research on Cancer (IARC), Our Future Health, Alcohol Change UK, Union for International Cancer Control (UICC), the Alcohol Health Alliance and the Obesity Health Alliance among many others.  

We were also able to secure significant public and media engagement, including national press and powerful stories from people living with and beyond cancer, as well as support from MPs across their own channels. On 22 June, we also attended a roundtable on misinformation in the UK Parliament organised by author Deborah Cohen, which was another important moment in building momentum around this issue.  

Cancer misinformation is an ongoing issue that we are taking very seriously. Together, we are stronger and together, we can help ensure people have access to information they can trust so that we can all live longer, healthier and happier lives free from the fear of cancer.  

Every day, millions of people search online for answers about cancer, diet and health. Some of what they find is accurate and helpful. Much of it is not. And when it comes to cancer – a subject where fear, hope and complexity are factors – misleading information can cause real harm.

Proving the challenge

There is no doubt that social media influencers promote a vast amount of misinformation online, especially to younger people. New YouGov polling, commissioned by World Cancer Research Fund for Cancer Prevention Action Week (15–21 June 2026), reveals a striking pattern:

• Among adults who rely on social media as their main news source, 13% wrongly believe that certain foods or diets can “starve” cancer, compared with 7% of other adults.
• 15% wrongly think certain supplements can reduce cancer risk, compared with 11% of other adults who prefer sources other than social media.
• Younger adults are particularly affected: 20% of 18–34-year-olds say they are more likely to trust a health claim if it is shared by an influencer or account they follow, compared with just 7% of over-55s.

Positive influencers speak out

However, there are also large numbers of influencers and experts online who are fighting back against misinformation. We are enormously grateful to the more than 30 health professionals and experts who gave their time to support Science Not Fiction — their commitment and expertise made a real difference.

Deborah Cohen

Deborah Cohen is one such expert. A medically-qualified journalist and author of “Bad Influence”, she warns:

“Over time, [influencers’] recommendations can start to feel less like advice from a stranger and more like guidance from a trusted friend.

They sometimes use scientific language to create an impression of authority, while the actual evidence behind their claims is weak, selective or simply not there.”

For anyone affected by cancer, the stakes are high.

Dr Idrees Mughal, known as Dr Idz, is a medical doctor with a master’s degree in nutritional research and more than 1.5 million followers across TikTok and Instagram.

Dr Idz

He explains:

“The danger is not just wasted money, but that misinformation can push people away from evidence-based advice and proven cancer treatments.

When people delay or reject effective care in favour of unproven alternatives, the consequences can be devastating, and in some cases fatal.”

Professor Sander van der Linden is Professor of Social Psychology at the University of Cambridge and author of FOOLPROOF.

He frames the broader challenge.

Professor Sander van der Linden

He says:

“Misinformation about cancer is rampant. One of the most important challenges is empowering people with skills to discern wellness quackery from evidence-based advice.”

The picture is not all bad online. The experts and influencers who joined us aren’t alone. Many doctors, dietitians, cancer specialists and science communicators are actively using social media to challenge misinformation with clear, evidence-based information.

How to tell the difference: the TRUST Test practical tool

That is exactly why World Cancer Research Fund has developed the TRUST Test – a simple, practical framework for evaluating health and nutrition information wherever you come across it. It gives you a clear set of prompts to help you pause and check before acting on a claim – whether you are reading a health blog, watching a video or seeing a claim shared in a group chat.