Second primary melanomas in a cohort of 977 melanoma patients within the first 5 years of monitoring.

Background: In retrospective studies, a second primary melanoma (SPM) develops in 2%-20% of melanoma patients. Scarce evidence exists on the usefulness of total-body photography (TBP) and digital dermatoscopic documentation (DDD) for detecting SPMs.

Objective: The primary aim was to quantify the risk and investigate the time of occurrence of SPMs. Secondary aims were to identify risk factors for SPM and to assess the usefulness of TBP and DDD for SPM detection.

Methods: This prospective cohort included patients with recently diagnosed melanoma that underwent sequential clinical and dermatoscopic examinations for up to 5 years. Life table analysis and Kaplan-Meier survival analysis were performed. Multivariate Cox models were constructed to identify factors affecting the outcome.

Results: An SPM developed in 46 of 977 (4.7%) patients. Life table analysis revealed a 5-year cumulative risk of 8.0% for SPM. High nevus count, fair phototype, and occupational sun exposure were potent predictors of SPM. Of all new melanomas, 17.3% were diagnosed by clinical and dermatoscopic examination, 48.1% by TBP, and 34.6% by DDD.

Limitations: All patients followed the same protocol and diagnostic bias associated with sequential dermatoscopic imaging.

Conclusion: In this cohort, melanoma patients were at 8% risk of an SPM developing within 5 years. TBP and DDD significantly contributed to the early detection of SPM.