A randomized, prospective study, published online December 6, 2010, in the Journal of Clinical Oncology found that regular use of sunscreen reduced the risk of developing melanoma ? the deadliest form of skin cancer ? by half, including a 73% drop in risk for invasive melanoma The study included more than 1,600 adults participates in Australia.
?Our results send a general message of reassurance,? said Adele Green, MD, Acting Director and professor of epidemiology at the Queensland Institute of Medical Research in Queensland, Australia, who led the work. ?Most physicians would suggest sunscreen for protection against sunburn and against more common squamous skin tumors. This is the first trial of its kind evaluating sunscreen use against melanoma as an outcome. These findings now provide some assurance to medical professionals, public health authorities and the public in general that sunscreen can offer some protection against melanoma.?
While melanoma accounts for only 5 percent of skin cancer cases, it accounts for the majority of deaths from skin cancer. Sun exposure has long been associated with melanoma, but previous studies of sunscreen use and melanoma risk have been inconclusive, and the use of sunscreen as a preventative has been unclear.
Green and her co-workers randomly assigned 1,621 residents aged 25 to 75 in Nambour, Queensland, Australia, to daily or discretionary sunscreen use on the head and arms between 1992 and 1996. Participants also received beta carotene or placebo supplements during that period to see if their addition enhanced protection from skin cancers.
BR>Investigators followed study subjects until 2006 through annual or biannual questionnaires that focused on new skin cancers, sunscreen use and average time spent outdoors, and monitored regional pathology laboratories and the Queensland Cancer Registry for new reported melanomas as well. They assessed both sun exposure and past skin cancers in both groups at the beginning of the trial and in the decade-long follow-up after the active trial ended, finding that sun exposure continued to be the same in both groups. They also found that those participants who had been randomized to use sunscreen daily were somewhat more likely to continue to do so after the trial than those in the other group.
In the 10 years after the five-year trial ended, the team identified 22 new melanomas in the discretionary use group and 11 in the daily sunscreen use group ? a 50% reduction. Of these new melanomas, they found 11 invasive melanomas in the discretionary group compared to only three among the daily sunscreen users, or 73% fewer. Beta carotene had no harmful or protective effects on melanoma.
Green said the dramatic differences were unexpected. ?While we thought we might see some differences in early or superficial melanomas, we were especially surprised at the reduction in the more dangerous invasive melanomas,? she said. ?It appeared to be quite strong protection.?
Green noted that previous studies had compared melanoma risk in individuals who chose to use sunscreen and those who did not, but the results were difficult to interpret. She stressed the importance of an intervention study where people were randomized to a protocol to use sunscreen regularly. In addition, her team?s research was in adults, complementing an earlier Canadian intervention study of sunscreen use in children. The earlier study had indicated a potential for sunscreen to protect against mole development in children, and moles are closely linked to melanoma risk. Green suggested that a study of the possible very long-term benefits of sunscreen use in youth might be valuable.
She also would like to see more behavioral research focus on ?assessing enhancement of, and barriers to, regular use of sunscreen? by individuals who are susceptible ? including those at high risk of melanoma or who live in regions with high sun exposure.
Commenting on the study, Robert P. Sticca, MD, Member, ASCO?s Cancer Communications Committee noted: ?These results are important because the issue of sunscreen as a potential preventative against melanoma has been debated for some time. Such large trials are difficult to do, and this paper provides the first prospective randomized data on the subject, which should help clinicians in their recommendations for patient care.?
Green AC, Williams GM, Logan V, Strutton GM. Reduced Melanoma After Regular Sunscreen Use: Randomized Trial Follow-Up. JCO December 6, 2010.
For more information:
- Cancer.Net Guide to Melanoma
- Cancer.Net Guide to Familial Malignant Melanoma
- Genetics of Melanoma
- Cancer.Net Feature Article: Protecting Your Skin from the Sun
- Cancer.Net Podcast: Protecting Your Skin from the Sun
- Cancer.Net Video: Melanoma: An Introduction with Lynn Schuchter, MD