Can exposure to sunlight reduce risk of breast cancer? Here’s what a new study says

According to a new study, exposure to sunlight may help reduce the risk of breast cancer — the second most common cancer affecting women, after skin cancer, in the US.
The paper from University of Buffalo and the University of Puerto Rico in the US, which was published in the Journal of Cancer Epidemiology, Biomarkers and Preventions, comprised a population-based case – control study of breast cancer among women in metropolitan San Juan, Puerto Rico, examining a cumulative sun exposure index (SEI) based on a comparison of reflectance of sun-exposed and non-exposed skin.
The researchers used a chromameter to measure skin reflectance and estimate the difference between constitutive (unexposed) and facultative (exposed) skin pigmentation in 307 cases and 328 controls. The Puerto Rico study noted that breast cancer risk factors were ascertained with interviewer-adminered questionnaires.

The study concluded that there was lower risk of breast cancer associated with greater sun exposure in a population living with high, continuous sun exposure due to higher levels of vitamin D. This beneficial finding should be placed in the context of other effects of sun exposure, it noted.
Vitamin D is called the sunshine vitamin because the body produces it when exposed to the sun’s ultraviolet B rays. Exposure to sunlight is said to be extremely rewarding for the body.
“Sun exposure is generally linked with skin cancers, however as per the study, there was reduction in breast cancer causation rates with increased sun exposure. The investigators correlated this finding with higher levels of vitamin D generated in the body in these women with higher sunlight exposure which was speculated to have lead to lower rates of breast cancer development. This is a very interesting finding that needs to be studied and validated further, specifically in the Indian population,” Dr Sewanti Limaye, director, Medical Oncology, Precision Oncology and Clinical and Transitional Oncology Research, Sir H N Reliance Foundation Hospital said.
Dr Kanika Sharma, Radiation Oncolog, Dharamshila Narayana Superspeciality Hospital said that as per few observational studies in US, higher sun exposure decreases the chances of developing this malignancy 11 per cent. “This happens due to the fact that the human body synthesises vitamin D on exposure to the sun. This helps with decreasing inflammation, improving body’s natural circadian rhythm, and managing obesity. The sun also improves mental health, strengthens the immunity and bones,” Dr Sharma told indianexpress.com.
Sunlight is necessary for vitamin D production (Photo: Pixabay)
Dr Kapoor also added that research suggests that women with low levels of vitamin D have a higher risk of breast cancer. Vitamin D may play a role in controlling normal breast cell growth and may be able to stop breast cancer cells from growing.

“There is a strong association of the sunshine vitamin with many other types of cancers like ovarian, colon, and multiple myelomas. Not just cancer, this is beneficial for other ailments like diabetes, bone diseases, cardiovascular ailments, multiple sclerosis. This wonder vitamin helps in the repair of defective genes, which can cause multiple problems,” said Dr Kapoor.
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