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

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