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Stephen J.LurieMD, PhD, Senior EditorIndividualAuthorPhil B.FontanarosaMD, Executive Deputy EditorIndividualAuthor
In Reply: We agree with Mr Barzilai that our
study likely underestimates the true value of broad-spectrum sunscreens in
attenuating new nevi in children. It is true that an ideal study to evaluate
the efficacy of sunscreen as a protective factor against new nevi would randomize
children into groups using sunscreen vs not using sunscreen. Such a trial
design, however, would be unethical.
Barzilai suggests that we ignore the randomization and compare number
of new nevi in children using sunscreen to avoid "unprotected sun episodes"
with those not using it for this purpose. Unfortunately, this would negate
one of the major benefits of a randomized trial—avoidance of uncontrolled
confounding by host susceptibility factors. Results from previous nonrandomized
studies consistently show a positive association between sunscreen use and
new nevi.1,2 We think these
results are most likely due to imperfect control of host susceptibility. Barzilai's
suggestion that we adjust for susceptibility by measures of skin reflectance
and other variables has not worked in past studies, and we have no reason
to believe that our host susceptibility assessment variables are superior
in any way to those of other investigators.1,2
The true degree of protection afforded by sunscreen against nevi will
probably always be underestimated because of ethical concerns and practical
considerations surrounding sunscreen trials. For public health purposes, we
feel it is enough to demonstrate that these compounds do afford some degree
of protection against melanoma precursor lesions.
Gallagher RP, Bajdik CD, Lee TK, Rivers JK, McLean DI, Coldman AJ. Efficacy of Sunscreen in Preventing Nevi—Reply. JAMA. 2000;284(22):2870. doi:10.1001/jama.284.22.2869
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