I thought this post would be particularly fitting with summer right around the corner.
I was doing some reading and came across this article, which summarized a study that examined the relationship between sun exposure (along with some other risk factors) and the risk of different types of skin cancers. In this study, researchers were able to follow 108,916 US women over 20 years and determined that having five or more blistering sunburns between ages 15 and 20 resulted in an 80% increased risk for melanoma. Moreover, women in the same age range had a 68% increased risk for basal cell carcinoma and squamous cell carcinoma after having five or more blistering sunburns.
At this point, you may be wondering how many blistering sunburns you’ve had in the past five years—after all, an 80% increase in risk for the skin cancer that accounts for the vast majority of skin cancer deaths may sound downright terrifying (I was certainly shocked to hear the stat). If you have had five or more blistering sunburns before 20, you may even feel helpless after hearing this statistic. But not to worry, the risk might not be as horrifying as statistical evidence makes it seem.
The above graph from the American Cancer Society’s Cancer Facts and Figures 2013 shows the probability of developing invasive cancers over multiple age intervals. I have drawn a red box around melanoma. Note that upon looking at the Birth to Death group, males have a 2.87% chance of developing melanoma in their lifetime and women have a 1.85% chance. That averages out to a little over 2%, meaning people in general have slightly more than a 2% chance of developing melanoma. When 5 or more blistering sunburns before 20 increases this chance by 80%, the risk of melanoma isn’t even 5%.
In closing, I think this article is a good example of how statistical evidence can be blown out of proportion. Sure, there is an 80% increased risk for melanoma after having 5 or more blistering sunburns before 20, but without the context of the probability for getting melanoma (which the article doesn’t provide), the article makes it seem like 4 out of 5 people with 5 or more blistering sunburns will undoubtedly develop melanoma later in life. But that’s obviously not the case. Even with the 80% increase, the chances of these people getting melanoma are still extremely small, and it’s probably even smaller if you’re not a part of a subset of individuals who have higher risks of getting melanoma. A 5% risk might still be a little scary, but it certainly isn’t as terrifying as 80%--that’s enough to make you never want to see the light of day again. But that doesn’t mean you should avoid taking precautionary measures against skin cancers. Just remember this: when you’re lying on a beach somewhere this summer, take the time to use sunscreen and avoid blistering. The odds will still be in your favor even if you’ve already had many blistering sunburns, but you certainly don’t want to do anything that will ensure that at some point in you’re life you become a part of that unfortunate 5%.
"Cancer Facts & Figures 2013." Cancer Facts & Figures 2013. American CancerSociety, n.d. Web. 27 Feb. 2014.<http://www.cancer.org/research/cancerfactsfigures/cancerfactsfigures/cncer-facts-figures-2013>.
"Five or More Blistering Sunburns before Age 20 May Increase Melanoma Risk by 80Percent." Mdconnects.com. N.p., 30 May 2014. Web. 1 June 2014.<http://www.mdconnects.com/articles/1655/20140530/five-moreblistering-sunburns-before-age-20-increase-melanoma-risk.htm>.