Ten-year survival after multiple invasive melanomas is worse than after a single melanoma: a population-based study.

Abstract

The prognosis of melanoma patients who are diagnosed with multiple primary lesions remains controversial. We used a large, population-based cohort to re-examine this issue, applying a delayed entry methodology to avoid survival bias. Of 32,238 eligible patients diagnosed between 1995 and 2008, 29,908 (93%) had a single invasive melanoma, 2,075 (6%) had two and 255 (1%) had three. Allowing for differences in entry time, 10-year cause-specific survival for these three groups was 89% (95% CI = 88%-90%), 83% (95% CI = 80%-86%) and 67% (95% CI = 54%-81%), respectively. After adjustment for key prognostic factors, the hazard ratio (HR) of death within 10 years from melanoma was two times higher for those with two melanomas (HR = 2.01, 95% CI = 1.57-2.59; p<0.001) and nearly three times higher when three melanomas were diagnosed (HR = 2.91, 95% CI = 1.64-5.18; p<0.001) compared to people with a single melanoma. Melanoma-specific mortality remained elevated after adjusting for maximum thickness or ulceration of any melanoma regardless of the index tumor. After appropriately accounting for the interval between diagnosis of the first and subsequent melanomas, patients with multiple invasive melanomas have significantly poorer survival than patients with a single invasive melanoma.