Volume 12, Number 7
As a bald, fair-skinned, white male, I have long been advised to avoid sun exposure, especially extensive sun exposure. The reason for this is that exposure to the ultraviolet (UV) rays in sunlight is a well-documented risk for skin cancer.
Some recent studies are leading me to reconsider my relationship with the sun. Several studies have concluded that even though avoidance of sun exposure may reduce mortality from skin cancer, sun avoidance is associated with increased mortality from all causes.
An important matter here is the danger of looking at disease-specific mortality without considering all-cause mortality. One example of this is that while lower cholesterol levels have been associated with reduced risk of death from heart disease, some investigations have found lower cholesterol levels to be associated with higher all-cause mortality rates. A similar debate may emerge regarding sun exposure, if additional studies corroborate the findings mentioned above.
Not surprisingly, Vitamin D gets a good deal of attention in considerations of sun exposure. It is known that higher vitamin D levels are associated with reduced risk for hypertension and other cardiovascular diseases. However, oral vitamin D supplementation has not been shown to convey this benefit, bolstering the argument for the importance of getting Vitamin D from the sun. Additionally, some investigators are suggesting that there are cardiovascular benefits from sunlight apart from vitamin D, based upon epidemiological data which indicate that more sun exposure is associated with lower blood pressure levels and reduced risk of cardiovascular death. One theory is that release of nitric oxide from the skin, induced by ultraviolet rays, may have beneficial effects on the cardiovascular system.
There is no argument with the conclusion that sun exposure increases risk for skin cancer, but there is some debate over what type of sun exposure is most risky. Basal cell and squamous cell carcinomas are generally non-fatal, whereas malignant melanoma has much higher mortality rates. Melanomas represent only about 1% of skin cancers but are responsible for most skin cancer deaths. Some argue that cumulative sun exposure is primarily what increases risk for basal call and squamous cell cancers, whereas episodic and excessive sun exposure (i.e., sunburn) is what conveys the primary melanoma risk. The intense UV exposure that occurs with tanning beds is a dangerous activity because it is without any benefits that otherwise may come from the sun.
In the United States in 2014, 614,348 deaths were attributed to heart disease, while 591,699 deaths were attributed to cancer. Of the cancer deaths, approximately 10,000 were from malignant melanoma. In other words, dying from heart disease is much more likely than is dying from melanoma. From these numbers, one could conclude that getting more sun exposure to help control blood pressure is a higher priority than avoiding sun exposure, even if this comes with an increased risk for skin cancer. This might especially be the case if the increased sun exposure is regular and moderate, rather than episodic and intense.
But, I’m not yet ready to make a major change in my behavior regarding sun exposure. So far, the largest studies indicating higher mortality rates with restricted sun exposure have been with Swedish women, so more research is needed. Furthermore, agencies such as the Centers for Disease Control and the United States Preventive Services Task Force continue to recommend minimizing exposure to ultraviolet radiation.
As a consumer of research regarding the risks and benefits of various health behaviors, it is important that I be mindful of the distinction between disease-specific mortality and all-cause mortality. I don’t want to make the mistake of lowering my risk for a lower probability illness at the cost of increasing my risk for a higher probability illness by focusing only on disease-specific data.
Paul J. Hershberger, Ph.D.
… is a clinical health psychologist. He is Professor of Family Medicine and Director of Behavioral Science for the Family Medicine Residency Program, Wright State University Boonshoft School of Medicine. His clinical practice includes psychotherapy, consultation, and coaching.
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