Am Fam Physician. 2010 Oct 15;82(8):989-990.
Does sunscreen use prevent skin cancer?
Daily sunscreen use reduces the incidence of squamous cell carcinoma but not the incidence of basal cell carcinoma. (Strength of Recommendation [SOR]: B, based on a single randomized controlled trial with less than 13 years of follow-up). It is unclear whether there are longer-term effects. There is no consistent, conclusive evidence that sunscreen use prevents melanoma. (SOR: C, meta-analysis of case-control studies).
SQUAMOUS CELL CARCINOMA
In a randomized controlled trial, 1,621 participants in Nambour, Australia, were randomized to one of four treatment groups. Of the two groups assigned to daily sunscreen use, one group (n = 404) applied sun protection factor (SPF) 15 sunscreen to the head, neck, arms, and hands, and received daily oral beta carotene supplementation. The second group (n = 408) was assigned to sunscreen application plus an oral placebo. Of the two groups not assigned to daily sunscreen use, one group (n = 416) received daily oral beta carotene supplementation, and the other group (n = 393) received daily oral placebo. Participants who were not in the daily sunscreen groups were allowed discretionary use of sunscreen.1
Over 4.5 years, persons in the daily sunscreen groups had a decreased incidence of squamous cell tumors at the sites of sunscreen application compared with those in the no daily sunscreen groups (28 tumors in 22 persons versus 46 tumors in 25 persons; rate ratio [RR] = 0.61; 95% confidence interval [CI], 0.46 to 0.81; number needed to treat = 140).1 Each group included persons of all skin types, with more than 50 percent of persons in each group having fair skin and 20 percent reporting that they “always burn.” An intention-to-treat analysis of 1,383 participants eight years after completion of the initial randomized controlled trial demonstrated a prolonged protective effect, with a 35 percent lower incidence of squamous cell carcinoma in the daily sunscreen groups (RR = 0.65; 95% CI, 0.43 to 0.98; number needed to treat = 2.8).2
BASAL CELL CARCINOMA
In the Nambour study, the incidence of basal cell carcinoma in the daily sunscreen groups compared with the no daily sunscreen groups was not statistically significant after 4.5 years (153 tumors in 65 persons versus 146 tumors in 63 persons; RR = 1.05; 95% CI, 0.82 to 1.34).1 In the eight-year follow-up study, there was no statistically significant decrease in the incidence of basal cell carcinoma (RR = 0.75; 95% CI, 0.49 to 1.14).2 In an additional multifailure survival analysis, none of the three analysis models found a significant difference in the risk of subsequent basal cell carcinoma.3
A meta-analysis of 11 case-control studies involving 9,067 patients evaluated the effect of sunscreen use on the incidence of melanoma.4 Results were heterogeneous and included study data from population-based and hospital-based sources. The analysis did not find an altered rate of melanoma with sunscreen use (combined RR = 1.11; 95% CI, 0.37 to 3.32). A review of 18 case-control studies examining sunscreen use in patients with melanoma found no significant association between melanoma and sunscreen use after controlling for skin sensitivity.5
Recommendations from Others
The American Academy of Dermatology recommends year-round application of broadspectrum sunscreen with SPF 30 or higher to all areas of the body exposed to the sun.6
Copyright Family Physicians Inquiries Network. Used with permission.
REFERENCESshow all references
1. Green A, Williams G, Neale R, et al. Daily sunscreen application and betacarotene supplementation in prevention of basal-cell and squamous-cell carcinomas of the skin: a randomised controlled trial [published correction appears in Lancet. 1999;354(9183):1038]. Lancet. 1999;354(9180):723–729....
2. van der Pols JC, Williams GM, Pandeya N, Logan V, Green AC. Prolonged prevention of squamous cell carcinoma of the skin by regular sunscreen use. Cancer Epidemiol Biomarker Prev. 2006;15(12):2546–2548.
3. Pandeya N, Purdie DM, Green A, Williams G. Repeated occurrence of basal cell carcinoma of the skin and multifailure survival analysis: follow-up data from the Nambour Skin Cancer Prevention Trial. Am J Epidemiol. 2005;161(8):748–754.
4. Huncharek M, Kupelnick B. Use of topical sunscreens and the risk of malignant melanoma: a meta-analysis of 9067 patients from 11 case-control studies. Am J Public Health. 2002;92(7):1173–1177.
5. Dennis LK, Beane Freeman LE, VanBeek MJ. Sunscreen use and the risk for melanoma: a quantitative review. Ann Intern Med. 2003;139(12):966–978.
6. American Academy of Dermatology. Facts about sunscreens. Schaumburg, Ill.: American Academy of Dermatology. http://www.aad.org/media/background/factsheets/fact_sunscreen.htm. Accessed September 9, 2010.
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