Body size and the risk of cancers – data from Catalonia

Talita Duarte-Salles's research study looks at body size and the risk of developing 22 major cancers using data from the Information System for the Development of Research in Primary Care collected on six million Catalans

  • Topic: Combination of cancers
  • Institution: IDIAP Jordi Gol
  • Country: Spain
  • Status: Ongoing

Co-applicants

Dr Heinz Freisling, International Agency for Research on Cancer (IARC-WHO), France
Dr Isabelle Romieu, International Agency for Research on Cancer (IARC-WHO), France
Professor Michael Leitzmann, University of Regensburg, Germany

Scientific abstract

(View plain language abstract)

Background

Increased body mass index (BMI) is an established risk factor for several cancers. There is convincing evidence for positive associations between BMI and cancers of the oesophagus (adenocarcinoma), pancreas, colon, rectum, breast (postmenopausal), endometrium, liver, kidney and probable evidence for gallbladder, ovary, and prostate. However, data is currently limited for many cancers.

Recently, a population-based cohort study of UK adults reported associations between BMI and 17 cancers, suggesting wider-ranging associations. These observations are important and need replication in other populations.

Furthermore, there is a crucial need for better characterisation of existing obesity-cancer links to determine dose-response relationships and effect modification by important individual factors across a wide range of cancers.

Another important issue is whether or not BMI alone can fully capture the complex biology underlying associations between adiposity and cancer, or whether individuals with similar BMI have distinct cancer risk depending on body fat distribution. Waist circumference (WC) is used as an indicator of central adiposity and has been suggested to be a superior cancer risk predictor.

Finally, few studies have investigated the association between overweight/obesity and cancer from a life course perspective, in part due to a lack of data on repeated weight measurements over a long duration of follow-up and sufficiently large cohort sizes.

Hypothesis and objectives

The main objective is to investigate the relationships between adiposity and 22 site-specific cancers using measured BMI and outcome data from prospectively collected primary care records in 6 million individuals from a Mediterranean population.

Specific objectives are to investigate:

  • Non-linear dose-response associations and effect modification by individual factors (eg hormone use)
  • Relations of duration of overweight/obesity to site-specific cancer using repeated measures of BMI
  • To derive standardized risk estimates for general (BMI) and central adiposity (WC) in relation to site-specific cancers

Settings and methods

We will use information from a prospective population-based database from the Information System for the Development of Research in Primary Care (SIDIAP). SIDIAP includes anonymized patient records data for nearly six million people throughout Catalonia since 2005. SIDIAP includes all data collected by health professionals during routine visits, including anthropometric measurements, clinical diagnoses, demographic and lifestyle information. The high quality of these data has been documented. Subjects aged >=15 years with BMI data and subsequent follow-up will be included. Baseline BMI will be assigned as the earliest BMI recorded. Repeated weight measurements will be used to predict individual BMI trajectories. Approximately 429,614 first primary cancers have been recorded from 2005-2015. Hazard ratios will be calculated using Cox models, and spline models will be fitted to investigate the dose-response nature of the associations. Overweight/obesity duration will be estimated using quadratic growth models.

Impact

This project will represent one of the largest studies in this area of research to date and will substantially advance our understanding of the impact of obesity on cancer risk. It will strengthen the rationale to implement obesity prevention strategies, thereby mitigating the adverse clinical and public health effects of obesity on cancer development.

Plain language abstract

Background

A high body mass index (BMI) is an established risk factor for several cancers. Previous studies have provided convincing evidence for positive associations between BMI and 8 cancers, as well as probable evidence for 3 additional cancers. However, data are currently limited for many other cancer sites.

Recently, a population-based cohort study of UK adults reported associations between BMI and 17 cancers, suggesting wider-ranging associations. These observations are important and need replication in other populations.

Furthermore, BMI alone may not fully capture the complex biology underlying associations between body fat and cancer risk, and individuals with similar BMI may have distinct cancer risk depending on their body fat distribution. Waist circumference (WC) has been previously suggested to be a superior predictor of cancer risk.

Furthermore, there is a crucial need for better characterisation of existing obesity-cancer links to determine dose-response relationships and effect modification by important individual factors across a wide range of cancer sites.

Aims and objectives

The main objective of this project is to investigate the relationships between body fat and 22 specific cancers using measured BMI and cancer diagnoses data from prospectively collected primary care records in 6 million individuals from a Mediterranean population.

Specific objectives are to investigate:

  • Non-linear dose-response associations and effect modification according to individual factors (eg hormone use)
  • Relations of duration of overweight/obesity to specific cancers using repeated measures of BMI
  • The role of general (BMI) and obesity (WC) on cancer development

How it will be done

The proposed study will use information from a prospective population-based database from the Information System for the Development of Research in Primary Care (SIDIAP). SIDIAP includes data of anonymized patient records for nearly six million people throughout Catalonia since 2005. SIDIAP includes all data collected by health professionals during routine visits, including anthropometric measurements, clinical diagnoses, as well as demographic and lifestyle information. The high quality of these data has been previously documented. All people in SIDIAP aged >=15 years with BMI data and subsequent follow-up will be included. Measured BMI (weight/height2) will be calculated and assigned as the earliest BMI recorded in the electronic healthcare history. Repeated weight measurements will be used to predict individual BMI trajectories for each study participant. Approximately 429,614 first primary cancers have been recorded from 2005-2015. The data will be analysed using sophisticated statistical methods to investigate the dose-response nature of the observed associations. Overweight/obesity duration will be estimated using innovative statistical methods.

Potential impact

This project is one of the largest studies in this area of research to date and it represents a unique opportunity to better understand the impact of obesity on cancer risk, including rare cancers occurring at young ages. The knowledge gained in this project will reinforce the importance of implementing obesity prevention strategies in order to reduce the public health burden of cancer due to obesity.