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%.
References
"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>.
