Extremity Nevus Count and Risk of Melanoma
Posted: Monday, May 6, 2019
An extremity nevus seems to correlate with a greater risk of basal cell carcinoma and melanoma but has no effect on the risk of squamous cell carcinoma, according to a prospective study. Men and women with a nevus count of 15 or more had the greatest risk. The results were published in the Journal of the American Academy of Dermatology by Hongmei Nan, PhD, of Indiana University, and colleagues.
“Providers should be aware of these increased risks in patients with any nevi on the extremity, with special attention to those with greater than or equal to 15 extremity nevi,” wrote the authors.
The study examined cohorts of 32,383 men (from the Health Professionals Follow-up Study) and 176,317 women (from the Nurses’ Health Study 1 and 2) from the years 1986 to 2013. Participants self-reported extremity nevus count in 1 of 7 categories (none, 1–2, 3–5, 6–9, 10–14, 15–20, or 21 or more) at the beginning of the study. The cohorts developed 30,457 cases of basal cell carcinoma, 1,704 cases of melanoma, and 2,296 cases of squamous cell carcinoma.
Extremity nevus count was associated with a risk of melanoma and of basal cell carcinoma. People with at least 15 extremity nevi were more likely to develop melanoma and 40% more likely to develop basal cell carcinoma compared with those who had no extremity nevi. There was no association between nevus count and squamous cell carcinoma.
A limitation of the study is that nevus count was self-reported. However, the study is strengthened by its large size, and the authors controlled for many confounding risk factors, including age, body mass index, smoking, alcohol intake, hair color, melanoma in a first-degree relative, childhood reaction to sun, lifetime severe sunburns, average sun exposure, and ultraviolet flux.
Disclosure: The study authors reported no conflicts of interest.