Increased incidence of second primary melanoma in patients with a previouscutaneous melanoma

Background: Patients with cutaneous melanoma reportedly have an increased r isk of developing second primary melanoma; however, this increased risk has not been well characterized with respect to age and time from first melano ma. we hypothesized that, as a result of temporal variations in environment al exposure, genetic susceptibility, and impaired immune competence, the in cidence of second primary melanoma varies significantly with respect to age and time. Methods: A review of our prospective melanoma data base, containing records for 8928 patients, was undertaken to identify patients with American Joint Committee on Cancer stage I and II cutaneous melanoma, who were treated fr om 1971 to 1998. Results: Second primary melanoma was identified in 113 (3.4%) of 3310 patie nts with American Joint Committee on Cancer stage I and II cutaneous melano ma. In 11 patients (0.3%), the second melanoma was identified within 2 mont hs of the initial tumor; the remaining 102 patients had a metachronous lesi on. The incidence rate of second primary melanoma was 325 per 100,000. The standardized incidence ratio, defined as the ratio of the number of observe d second melanomas to the number of expected melanoma cases, was 25.6. The 5- and 10-year risk of developing a second melanoma was 2.8% and 3.6%, resp ectively. Both the annual risk of developing a second melanoma and the stan dardized incidence ratio were elevated in younger patients (ages 15-39 year s) and in older patients (ages 65-79 years). Conclusions: Patients with cutaneous melanoma are at very high risk for dev elopment of second primacy melanoma. This risk approximates 0.5% per year f or the first 5 years of follow-up. Patients aged 15-39 and patients aged 65 -79 have a particularly high incidence of second melanoma, suggesting diffe rent causes for the development of second primaries. All patients with mela noma should undergo careful surveillance for second melanomas in addition t o routine screening for recurrence.