A study identified the number of nevi present on a patient’s skin and high genetic predisposition to melanoma as 2 specific risk factors present in patients more likely to experience an incidence of a second primary melanoma.

“Understanding the risk factor profile of patients diagnosed with second and subsequent primary melanomas may provide new insights into disease etiology and support greater prevention efforts in those at higher risk,” wrote Dr Catherine M. Olsen, PhD, QIMR Berghofer Medical Research Institute, Queensland, Australia, and colleagues.

The population-based, prospective cohort study included 38 845 patients. During a median follow-up period of 7.4 years, 1212 (3.1%) patients had a single primary melanoma diagnosis, and 245 (0.6%) had a second primary melanoma diagnosis. The main outcomes of the study were the incidence of first or second primary melanoma diagnosis, as well as the histologic and clinical characteristics of those instances, recorded to identify potential risk factors specifically associated with secondary melanoma diagnosis.

Study results found that having many moles at age 21 years – defined via a visual scoring tool used by patients to self-report – was more strongly associated with second (hazard ratio [HR] 6.36, 95% confidence interval [CI] 3.77 to 10.75) than first primary melanoma (HR 3.46, 95% CI 2.72 to 4.4; P = .01). A high genetic predisposition (defined as polygenic risk score in tertile 3) was also more closely associated with second (HR 3.28, 95% CI 2.06 to 5.23) than first melanoma (HR 2.06, 95% CI 1.71 to 2.49; P = .03). Additionally, second melanomas were more strongly linked with a history of multiple skin cancer excisions (HR 2.63, 95% CI,1.8 to 3.83) compared with first melanomas (HR 1.86, 95% CI 1.61 to 2.16; P = .05). The study observed similar levels of association with first vs second melanomas for all other considered phenotypic characteristics and sun exposure measures.

Dr Olsen et al explained their “findings showed that many of the classic phenotypic risk factors for melanoma were similarly associated with risk of first and second melanomas; however, high numbers of nevi and high genetic predisposition were more strongly associated with second than first primary melanomas.” They concluded, “The role of diagnostic scrutiny in detecting second and subsequent melanomas has not been investigated fully here and should be the focus of future analyses.”

Source:

Olsen CM, Pandeya N, Dusingize JC, et al. Risk factors associated with first and second primary melanomas in a high-incidence population. JAMA Dermatol. Published online: November 23, 2022. doi: 10.1001/jamadermatol.2022.4975