Men employed in occupations requiring them to work outdoors have lower risk of kidney cancer compared to their male counterparts who work indoors, according to a new study.
Sara Karami, Ph.D., of the National Cancer Institute in Rockville, Md., and her colleagues designed a case-control study—the largest of its kind— to explore whether occupational sunlight exposure is associated with kidney cancer risk because the incidence of kidney cancer and the prevalence of vitamin D deficiency have increased over the past few decades.
Research suggests that vitamin D obtained from sun exposure, some foods, and from supplements may help prevent some cancers. Vitamin D is metabolized and most active within the kidneys.
While the study, published early online in Cancer, the peer-reviewed journal of the American Cancer Society, did not directly address if high sunshine exposure can help prevent kidney cancer, it did find that men exposed to daily sunshine reduced their kidney cancer risk as much as 38 percent. However, women who spend their occupational hours outdoors do not reap any benefits.
The authors have no explanation why there are observed risk differences between men and women, but they offered several hypotheses. Foremost, biological or behavioral differences between men and women may be at play. For example, hormonal differences may influence the body's response to sunlight exposure. Females also have a higher tendency to use sunscreen on a regular basis, and men are prone to working outdoors while shirtless. It is also possible that the observed sex differences in risk were due to other unmeasured kidney cancer risk factors, such as recreational sunlight exposure and physical activity levels.
While this study's findings raise the possibility of a link between sunlight exposure and kidney cancer risk, "they clearly need to be replicated in other populations and in studies that use better estimates of long-term ultraviolet exposure and vitamin D intake," said Dr. Karami.
Excessive sun exposure is directly linked to the increase of melanoma skin cancer, and can cause skin damage, eye damage, and immune system suppression.