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Skin Cancer Prevention (PDQ®)

Interventions With Inadequate Evidence as to Whether They Reduce Risk of Nonmelanoma Skin Cancer

Sunscreen Use and Ultraviolet (UV) Radiation Avoidance


The evidence that interventions designed to reduce exposure to UV radiation by the use of sunscreen, protective clothing, or limitation of sun exposure time decrease the incidence of nonmelanoma skin cancer is inadequate. A randomized study suggested a possible reduction in incidence of squamous cell carcinomas (SCCs), but study design and analysis problems complicate interpretation of the results.[1,2]

Magnitude of Benefit: Not applicable (N/A) (inadequate evidence).

  • Study Design: One randomized controlled trial (RCT) with tumor incidence as the outcome and one RCT with actinic keratosis as the outcome for SCC; cohort studies for basal cell carcinoma (BCC). Other study designs give inconsistent results.
  • Internal Validity: Poor.
  • Consistency: Poor.
  • External Validity: Poor.


The harms of sunscreen use are poorly quantified but are likely to be small, including allergic reactions to skin creams and lower production of vitamin D by the skin with less sun exposure.

It is possible that individuals who use sunscreen may experience excess sun exposure because they avoid sunburn but do not avoid harmful UV radiation.

Chemopreventive Agents


There is inadequate evidence to determine whether the use of chemopreventive agents reduces the incidence of SCC or BCC of the skin.

Magnitude of Effect: N/A (inadequate evidence).

  • Study Design: RCTs with tumor incidence as a post hoc subset.
  • Internal Validity: Poor.
  • Consistency: N/A.
  • External Validity: Poor.


Beta carotene use has been associated in RCTs with an increased risk of lung cancer incidence and mortality in smokers. Isotretinoin has dose-related skin toxicity. COX-2 inhibitors, such as celecoxib, have been associated with cardiac toxic effects in RCTs for the prevention of colorectal cancer.


  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. Lancet 354 (9180): 723-9, 1999. [PUBMED Abstract]
  2. van der Pols JC, Williams GM, Pandeya N, et al.: Prolonged prevention of squamous cell carcinoma of the skin by regular sunscreen use. Cancer Epidemiol Biomarkers Prev 15 (12): 2546-8, 2006. [PUBMED Abstract]
  • Updated: February 9, 2015