Extremity nevus count associated with increased risk of melanoma and basal cell—but not squamous cell—carcinoma

Reference

Wei EX, Li X, Nan H. Extremity nevus count is an independent risk factor for basal cell carcinoma and melanoma, but not squamous cell carcinoma. J Am Acad Dermatol 2019;80(4):970-978.

Synopsis

These investigators analyzed data from 3 well-known prospective cohort studies: the Nurses' Health Study (1976), the Nurses' Health Study 2 (1989), and the Health Professionals Follow-Up Study (1986). All participants (N = 208,700) were asked at inception to provide a melanocytic nevus count from either an arm or a leg. Exclusion criteria included a history of melanoma or other skin cancers at cohort inception. Individuals masked to exposure status validated outcomes data on skin cancer diagnoses. Multiple adjustments were made for potential confounders, including age, body mass index, smoking status, alcohol intake, childhood tanning and sunburns, geographic location, hair color, family history, and citrus ingestion. Compared with no nevi on the extremity, the risk of melanoma significantly increased with one or more nevi in a dose-dependent manner, with the greatest risk occurring in those individuals with at least 15 nevi on an extremity. Similarly, nevus extremity count was also significantly associated with an increased risk of basal cell carcinoma in a dose-dependent manner. However, no significant association occurred between nevus count and risk of squamous cell carcinoma.