Distinct Risks for Superficial Spreading, Lentigo Melanomas

Solar lentigines are strongest predictors of lentigo maligna, nevi of superficial spreading type

WEDNESDAY, Oct. 19 (HealthDay News) -- Lentigo maligna melanoma (LMM) and superficial spreading melanoma (SSM) have distinct risk profiles, with the strongest determinants of LMM and SSM being the number of solar lentigines and the number of nevi, respectively, according to a study published online Oct. 17 in the Archives of Dermatology.

Marina Kvaskoff, Ph.D., from the Institut National de la Santé et de la Recherche Médicale in Villejuif, France, and colleagues compared the risk factors for LMM versus those for SSM. A total of 49 patients with LMM and 141 with SSM (aged 14 to 86 years at diagnosis in 1979 and 1980) and 232 controls were interviewed during 1980 and 1981. Response rates were 97.1 and 91.8 percent in cases and controls, respectively. Multinomial logistic regression analysis was used to estimate risk of SSM and LMM in relation to phenotypic and environmental factors.

The investigators found that the number of solar lentigines was the strongest predictor of LMM versus being a significantly weaker predictor of SSM (odds ratio [OR], 15.93 versus 4.61). Having a history of skin cancer correlated significantly with LMM (OR, 2.84) but not with SSM. The number of nevi was the strongest determinant of SSM and had a significantly weaker association with LMM (OR, 23.22 versus 3.60). Multiple lifetime sunburns were not associated with LMM, but almost tripled the risk of SSM. The number of solar keratoses, and having a sun sensitive complexion (freckling, light eye/hair colors, and sunburn propensity) were associated with two- to five-fold increased risks for both SSM and LMM.

"Our data support the hypothesis that LMM and SSM have distinct etiologies," the authors write.

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