Multiple primary melanomas in Western Sweden; 1990-2013

Conference poster, 2016

Introduction In Sweden, the incidence of cutaneous malignant melanoma rises yearly with 5.5% for men and 5.2% for women and has now reached world standard rates of 17.6 for men and 18.8 for women per 100,000 population. Over the past decades, the incidence of melanoma has been higher in Western Sweden than the national average. Previous international studies have shown that melanoma patients have an elevated risk of developing a new separate primary melanoma. This study aimed at describing multiple primary melanomas (MPMs) in Western Sweden with focus on the number of tumours detected, tumour characteristics and the time to diagnosis of a subsequent melanoma. Methods Data was extracted retrospectively from the Swedish Melanoma Registry and provided information on all invasive and in situ melanoma cases in Western Sweden (1.6 million inhabitants) from 1990 to 2013. Results Within the studied period, 12,152 patients developed 13,291 melanomas. 11,254 of the patients developed only a single primary melanoma. In total, 898 patients (7.4% of all melanoma patients) developed 2,037 MPMs. Preliminary results show that the median Breslow thickness for all invasive melanomas was below 1 mm. The median Breslow thickness for the MPMs was slightly thinner for the second and third invasive melanoma as compared to the first invasive melanoma. Further, there was a higher percentage of in situ tumours among the subsequent melanomas. The median time to diagnosis of a subsequent melanoma was approximately 3 years. Discussion Subsequent primary melanomas in Western Sweden are most commonly diagnosed with a somewhat thinner Breslow thickness than the first primary melanoma. The comparatively high percentage of melanoma survivors developing MPMs and the short median time to diagnosis of a subsequent melanoma stresses the importance of follow-up for melanoma patients, particularly during the first years.