Association of multiple primary melanomas with malignancy risk: A population-based analysis of entries from the Surveillance, Epidemiology, and End Results program database during 1973-2014

Background: Genetic and environmental risk factors have been associated with the development of multiple primary melanomas (MPMs). We hypothesized that individuals with MPMs might have an increased incidence of internal malignancies.Objective: To identify the risk for subsequent malignancies in MPM patients.Methods: Multiple primary standardized incidence ratios were analyzed for individuals with >= 1, >= 2 and >= 3 primary melanomas (PMs) recorded in the Surveillance, Epidemiology, and End Results database during 1973-2014.Results: We identified 223,799 individuals with >= 1 PM, 19,709 with >= 2 PMs, and 3,995 with >= 3 PMs. Risks of subsequent internal malignancy increased with number of PMs, with observed:expected ratios of 0.99, 1.14, and 1.23 (P < .05) for patients with >= 1 PM, >= 2 PMs, and >= 3 PMs, respectively. Internal malignancy was higher in younger MPM patients and those with superficial spreading melanoma. The most common malignancies among MPM patients included breast, prostate, thyroid, soft tissue, brain, kidney, non -Hodgkin lymphoma, and chronic lymphocytic leukemia. Risk for subsequent cutaneous melanoma increased with observed:expected ratios of 8.09, 22.52, 41.03 (P < .05) for patients with >= 1 PM, >= 2 PMs, and >= 3 PMs, respectively.Limitations: Surveillance, Epidemiology, and End Results records limited information about pigmentation phenotypes, histology, and treatments.Conclusion: Patients with MPMs have an increased risk for subsequent internal and cutaneous malignancies and might benefit from tight adherence to age-specific cancer screening. ( J Am Acad Dermatol 2023;88:e211-9.)