Sunscreen Prevents Precancerous Spots
Daily Sunscreen Use Fights Early Signs of Skin Cancer
WebMD News Archive
April 21, 2003 - Applying sunscreen every day rather than only
on sunny ones makes a big difference when it comes to fighting the first signs
of skin cancer. A new study shows that daily use of sunscreen is much more
effective than sporadic use in preventing precancerous skin growths called
solar keratoses or SKs.
The skin lesions are the earliest forms of the most common
types of skin cancer caused by sun exposure, basal cell carcinoma and squamous
cell carcinoma. People who have SKs are up to 12 times more likely to develop
these forms of skin cancer than others.
Despite these risks, researchers say little is known about
sunscreen's role in preventing these early markers of skin cancer. In this
study, researchers compared the effects of daily versus occasional use of
sunscreen use in reducing the number of SKs in 1,621 adults living in
Queensland, Australia from 1992 to 1996.
One group was instructed to apply a water-resistant sunscreen
with an SPF (sun protection factor) of 16 each morning to their head, neck,
arms, and hands, and the other group was told to use sunscreen at their own
People who used sunscreen daily developed significantly fewer
SKs than the occasional sunscreen users, and the protective effects of daily
sunscreen use were especially strong in the first two and a half years of the
For example, the increase in SK counts from 1992 to 1994 in the
group that used sunscreen daily was about 24% lower than the increases found in
the occasional-use group. Researchers say that reduction is equivalent to
preventing one precancerous growth per person over the four-year study.
The findings appear in the April issue of the Archives of
But researcher Steven Darlington and colleagues from the
Queensland Institute of Medical Research in Australia say their study may
actually have underestimated the protective effects of sunscreen in preventing
skin cancer because it didn't compare daily sunscreen use to not using
sunscreen at all. Due to the well-known risks of skin cancer in a subtropical
environment such as Australia, researchers opted to allow their comparison
group to use sunscreen as they would normally.
Dermatologist Arielle Kauvar, MD, says these findings are
encouraging because the protective effects of sunscreen in reducing skin cancer
risk were especially dramatic in people that were younger or tanned easily.
"That tells us if you start using sunscreen on a regular
basis when you're young or before you have any visible skin damage that it will
have a better effect," Kauvar tells WebMD. "But it also had an effect
on people with preexisting damage."