PORTLAND, ORE. – Among white men, the presence of at least one cutaneous nevus measuring 3 mm or more significantly predicted death from melanoma, in an adjusted analysis of a large prospective cohort study.
Mole count also predicted melanoma death among white women, but the association reached statistical significance only when women had at least three cutaneous nevi measuring 3 mm or more, Eunyoung Cho, ScD, said at the annual meeting of the Society for Investigative Dermatology. The reasons why these associations varied by sex is unclear, although previous studies have documented higher rates of melanoma death among men than among women, and even male physicians tend to seek health care less frequently than their female counterparts, Dr. Cho said in her poster presentation.
Dr. Eunyoung Cho
In the Nurses’ Health Study, white women with at least three moles measuring at least 3 mm in diameter were at significantly increased risk of dying of melanoma, compared with those with no moles that size (hazard ratio, 2.5; 95% confidence interval, 1.5-4.1), even after the investigators controlled for many other potential confounders, including sunburn history, skin reaction to sun during childhood, tanning ability, family history of melanoma, personal history of nonmelanoma skin cancer, age, activity level, smoking, body mass index, alcohol intake, and hair color. Women with one or two moles also showed a trend toward increased risk of melanoma death (HR, 1.4), but the 95% confidence interval for the hazard ratio did not reach statistical significance (0.9-2.3).
The investigators estimated that among white women, each additional mole measuring 3 mm or more conferred about a 12% increase in the melanoma death rate, even after confounders were controlled for.
In the Health Professionals Follow-Up Study, men with one or two moles of at least 3 mm had about twice the melanoma death rate as men without moles of this size (HR, 2.0; 95% CI, 1.3-3.3), even after investigators controlled for potential confounders. The risk of melanoma death was even greater among men with at least three moles (HR, 4.0; 95% CI, 2.5-6.2), and the difference in rates was statistically significant (P less than .0001). After confounders were accounted for, each additional mole measuring at least 3 mm conferred a 20% increase in the rate of melanoma death.
A different picture emerged after narrowing the adjusted analyses to include only people diagnosed with melanoma: In this group, mole count did not predict melanoma death among women, but continued to do so among men with melanoma who had at least three moles at baseline (HR, 1.8; 95% CI, 1.1-3.0), Dr. Cho reported. Among men, higher mole count also predicted melanoma of at least 1-mm Breslow thickness, an important prognostic factor, she added. Hazard ratios for these “thicker melanomas” were 1.9 (95% CI, 1.1-3.3) among men with one or two moles, and 2.5 (95% CI, 1.5-4.4) among men with three or more moles. Among women with melanoma, mole count did not predict Breslow thickness.
The extent to which sex affected trends in this analysis highlights the need for more studies of sex and other phenotypic risk factors for melanoma death, Dr. Cho concluded. She presented on behalf of lead author Wen-Qing Li, PhD, also of Brown University.
The National Institutes of Health and the Dermatology Foundation provided funding. Dr. Cho and Dr. Li had no relevant financial disclosures.