Quick quiz question: two people are diagnosed with melanoma – Sarah Sunburn, an adamant sun-worshipper, and Paula Pale-All-The-Time, a fanatical sun-avoider. Who is more likely to die of the disease?
The answer is pale-faced Paula. Surprised? Let me unpack this mystery and explain why sun exposure simultaneously kills people, while making the cancers they are diagnosed with appear to be less life-threatening.
I will start with what you probably know already. Melanoma is a potentially life-threatening skin cancer. It occurs usually as a result of genetic risk, including fair complexion and sun exposure. (I lost my beloved redheaded aunt to melanoma when she was tragically young.) All else equal, people who spend more time in the sun, or in tanning booths, are more likely to die of melanoma, with people of fair complexion especially at risk.
Now here is the part that you might find confusing: among people diagnosed with melanoma, those with a history of lots of sun exposure and fair complexion are less likely to die. That’s right: sun exposure makes people both more and less likely to die of melanoma. How can that be?
It’s the difference between the rate of death from melanoma and the death rate of people diagnosed with melanoma.
(To read the rest of the article, please visit Forbes.)