Higher SPF sunscreen reduces risk for melanoma by 33%

Use of SPF 15 or higher sunscreen reduced the risk for melanoma by 33%, according to results of a population-based cohort study.

Further, incidence of melanoma would decrease 18% in the next 10 years if all women aged 40 to 75 years used at least SPF 15 sunscreen, results showed.

“Cutaneous melanoma is one of the most rapidly increasing cancers and a major public health challenge in white populations,” Reza Ghiasvand, postdoctoral fellow in the department of biostatistics at the Institute of Basic Medical Sciences at the University of Oslo, and colleagues wrote.

Because solar ultraviolet is an established cause of melanoma, physicians recommend sunscreen use for protection. However, high-quality evidence to support the use of sunscreen to prevent melanoma had been lacking.

Therefore, Ghiasvand and colleagues assessed risk for melanoma in relation to sunscreen use and sunbathing habits among 143,844 women aged 40 to 75 years from the Norwegian Women and Cancer Study.

In total, 722 women were diagnosed with melanoma (mean age at diagnosis, 60 years). Disease sites included lower limb (n = 266), trunk (n = 249), upper limb (n = 118), head and neck (n = 49), and multiple sites (n = 40). Most cases were superficial spreading melanoma (56%) or nodular melanoma (15%).

Compared with women with no sunburn history, those with the highest cumulative number of sunburns were more likely to live in areas with higher ambient ultraviolet radiation (52% vs. 40%), have at least 14 years of education (42% vs. 21%), have light skin color (45% vs. 28%), have blond or red hair (49% vs. 32%), and to have used sunscreen.

Further, sunscreen users were more likely to be in the youngest age groups; live in areas with high ambient ultraviolet radiation; have higher education, light skin color, blond or red hair, and freckling when sunbathing; and reported significantly more sunburns, sunbathing vacations and indoor tanning (P < .001).

Sunscreen users with a history of sunburn tended to have a higher risk for melanoma than sunscreen users with no history of sunburn.

The use of SPF 15 or higher sunscreen on at least one occasion appeared associated with a 33% reduction in risk for melanoma compared with consistent use of sunscreen less than SPF 15 (HR = 0.67; 95% CI, 0.53-0.83).

“The upward trend of using broad-spectrum high-SPF sunscreens along with improvement in application has the potential to decrease the incidence of melanoma and lower its burden in coming years,” Ghiasvand and colleagues wrote.

Researchers estimated the use of at least SPF 15 sunscreen would decrease the incidence of melanoma by 18% (95% CI, 4-30) in all women aged 40 to 75 years and by 21% (95% CI, 16-46) among women with blond or red hair. The incidence of melanoma among women who used sunscreen of less than 15 SPF would decrease 33% (95% CI, 16-46) if they switched to a higher SPF.

“During intentional sunbathing, use of SPF 15 or higher sunscreen can reduce melanoma risk compared with use of SPF lower than 15 sunscreen,” the researchers wrote. “Moreover, use of SPF 15 or higher sunscreen by all women age 40 to 75 years could lead to an 18% drop in melanoma incidence in approximately 10 years.”

In an accompanying editorial, Tamar Nijsten, MD, PhD, of the department of dermatology at Erasmus MC in Rotterdam, the Netherlands, acknowledged that the study raised several issues in a variety of areas, including questions on:

recent SPF use compared with prior use during childhood and adolescence, which is the strongest UV risk factor for melanoma development;

the effect of active ingredients from mineral filters or commonly used chemical filters;

the effectiveness of UVA and UVB rays absorbed in SPF 15 or higher; and

the variety of FDA and Environmental Working Group recommendations.

“Although the robust assessment of the protective effects of sunscreens on melanoma remains a daunting challenge, the [Norwegian Women and Cancer] study confirms common sense but raises several questions,” he added. “Appropriate sunscreen use is safe and should be part of UV protective interventions to prevent the development of melanoma.” – by Kristie L. Kahl

Disclosures: The researchers and Nijsten report no relevant financial disclosures.