How diet, nutrition and physical activity affect skin cancer risk. In total, we analysed 55 studies from around the world, covering nearly 13 million adults and over 56,000 cases of non-melanoma skin cancer and 27,000 cases of melanoma skin cancer.
Skin cancers can be divided into two main groups: melanoma and non-melanoma. In 2018, melanoma accounted for about 22% of skin cancer diagnoses, and non-melanoma tumours accounted for about 78% of skin cancer diagnoses. The most common non-melanoma tumours are basal cell carcinoma and squamous cell carcinoma.
Over-exposure to certain types of light, such as ultra-violet rays from the sun or tanning devices, is the principal cause of both melanoma and non-melanoma skin cancers.
Our Expert Panel has also reviewed the evidence on diet, weight, physical activity and the risk of skin cancer.
There is strong evidence that:
There is some evidence that:
In addition to both radiation, and the findings on diet, nutrition and physical activity outlined above, other established causes of skin cancer include:
Medicines used to suppress the immune system after organ transplantation are associated with increased risk of skin cancers, particularly squamous cell carcinoma.
Infection with human papilloma virus can cause squamous cell carcinomas of the skin, especially in people whose immune systems are compromised.
Exposure to specific chemicals used in the plastic and chemical industries – polychlorinated biphenyls – is strongly associated with an increased risk of skin cancer.
Some rare mutation in specific genes can lead to skin cancer. Having a family history of skin cancer also increases risk.
Skin cancer is more common in lighter-skinned populations than in darker-skinned populations.
Exposure to UV radiation is the primary cause of skin cancer. The role of sun damage is supported by the association between measures of sun sensitivity and skin cancer incidence, which is higher in people who have pale skin that burns without tanning, blue eyes and red hair. Both the duration and severity of exposure is important: there is a dose-response relationship between the number of sunburn episodes during any life period (childhood, adolescence or adulthood) and the risk of melanoma.
UV radiation can induce cellular changes consistent with the hallmarks of cancer, including inducing genomic instability and mutation, resisting cell death, activating sustained proliferative signalling and cell growth, as well as initiating tumour-promoting inflammatory responses.
UV radiation can directly damage DNA and also create cellular environments which are damaging to DNA, for example through the generation of reactive oxygen species. The activation of chronic inflammatory pathways helps generate an environment conducive to cancer development and progression and is associated with progression from actinic keratosis to squamous cell carcinoma.
Overall, UV radiation has a range of effects on skin cells, affecting several metabolic pathways that together create a cellular microenvironment conducive to the development and progression of cancer. These effects may be modulated by genetic factors.
In 2018, World Cancer Research Fund International published Diet, Nutrition, Physical Activity and Cancer: a Global Perspective on behalf of AICR, WCRF and WKOF. This was the third in our series of major reports looking at the many ways in which our diets, and how active we are, affect our cancer risk. You can find out much more about skin cancer by downloading a pdf of the relevant chapter in the 2018 report. Please note, however, that this webpage may have been updated since the report was published.