Multiple primary melanomas: implications for screening and follow-up programs for melanoma.

BACKGROUND: Once individuals are diagnosed with malignant melanoma, they are at an increased risk of developing another melanoma when compared with the normal population.
METHODS: To determine the impact of an intensive follow-up protocol on the stage of disease at diagnosis of subsequent primary melanomas, a retrospective query was performed of an electronic medical record database of 2,600 consecutively registered melanoma patients.
RESULTS: Sixty-seven patients (2.6%) had another melanoma diagnosed at the time of presentation to the clinic or within 2 months (synchronous) and another 44 patients (1.7%) developed a second primary melanoma during the follow-up period (metachronous). For the 44 patients diagnosed with metachronous lesions, the Breslow mean tumor thickness for the first invasive melanoma was 2.27 mm compared with 0.90 mm for the second melanoma. The first melanomas diagnosed are thicker by an average of 3.8 mm (p = 0.008). The mean Clark level for the initial melanoma was greater than the mean level for subsequently diagnosed melanomas (p = 0.002). Twenty-three percent of the initial melanomas were ulcerated, whereas only one of the second primary lesions showed this adverse prognostic factor (p = 0.002).
CONCLUSIONS: Once individuals are diagnosed with melanoma, they are in a high-risk population for having other primary site melanomas diagnosed and should be placed in an intensive follow-up protocol consisting of a complete skin examination.