The American Cancer Society predicts that 55,100 cases of melanoma will be diagnosed in 2004.1 More than 1 million new cases of basal cell and squamous cell carcinoma are expected.2
How effective are current measures to protect against skin cancer-and is counseling patients about their use likely to change their behavior?
IMPACT OF COUNSELING
Based on current evidence, it is unclear whether counseling patients on behaviors to prevent skin cancer is effective; however, counseling parents may increase the use of sunscreen in children. Therefore, the US Preventive Services Task Force (USPSTF) does not recommend either for or against routine skin cancer prevention counseling by primary care clinicians. The evidence that supports this position is summarized here.3
EFFECTIVENESS OF PREVENTIVE MEASURES
Sunscreen. Although sunscreen has been shown to prevent solar keratosis and squamous cell skin cancer, its effectiveness in preventing melanoma remains uncertain. Squamous cell skin cancer and its precursors may be better prevented by using sunscreens that block both UV-A and UV-B light rather than those that block only UV-B light.
Several epidemiologic studies have shown sunscreen users to be at higher risk for melanoma than non-users4-6; however, a recent meta-analysis of population-based case-control studies found that sunscreen use had no effect on melanoma risk.7 This conflicting evidence may reflect the increased use of sunscreen by persons already at higher risk for melanoma (such as those with fair skin) and the potential harm of sunscreen users spending increased time in the sun.
Observational studies show that long-term sun exposure and the ability to tan are associated with a lower risk, and intermittent or intense exposure is associated with an increased risk of melanoma.7-11 These results suggest that reducing childhood incidence of sunburn may decrease the lifetime risk of melanoma.
Reducing sun exposure. Effective measures to protect skin from ultraviolet light include staying indoors or in the shade, or covering exposed skin with clothing. However, no randomized trials have studied whether these sun avoidance behaviors prevent skin cancer. Sun exposure in childhood and adolescence is associated with an increased risk of nonmelanoma skin cancer, which commonly occurs in frequently exposed areas (such as the face). Potential harms of limiting exposure to the sun, such as negative effects on mental health and reduced physical activity in children, have not been studied.
Sunlamp and tanning bed avoidance. As a result of contradictory study results and limited study design, the role of sunlamps and tanning beds in the risk of melanoma remains unclear. While several studies have shown an association between sunlamp use and increased risk of melanoma,12 many did not correct for variations in the intensity or the timing of sunlamp use or exposure to natural sunlight. Among 9 studies that considered duration, frequency, or timing of sunlamp exposure, 4 found an association with risk of melanoma, especially in cases of high exposure resulting in sunburn.
Skin self-examination. One case-control study showed that patients who performed skin self-examination over a 5-year period had a lower risk of melanoma.13 However, the USPSTF concludes that this study does not provide enough evidence to show that patient skin self-examination either decreases the incidence of melanoma or improves the outcome of diagnosed cases.
Physician counseling. Although community and worksite interventions to promote skin cancer prevention are effective, data on successful physician counseling are limited. One study showed a 9% increase in children using sun protection (mainly in the form of sunscreen) after their parents received counseling from a physician regarding protective clothing, shade, and sunscreen.14 n
