Contrasting survival outcomes and patient characteristics in 5815 patients with stage II and III melanoma: a nationwide population-based registry study from Sweden.

Abstract

Prognostic stratification is essential for guiding treatment and follow-up in cutaneous melanoma. Previous international studies suggest that patients with localized stage IIB and IIC melanoma have poorer survival rates than those with lymph node involvement in stage IIIA. Nevertheless, Swedish guidelines still recommend less frequent follow-up for stage II than for patients with stage III. To evaluate melanoma-specific survival and characteristics of Swedish patients with stage II-III melanoma. This study included all Swedish adults diagnosed with stage II-III melanoma (pathologically confirmed) between 31 December 2018 and 1 January 2001. Data were obtained through linkage between the Swedish Melanoma Register, the National Cause of Death Register, and several other nationwide population-based registers. Clinicopathological characteristics, comorbidities and socioeconomic factors, in addition to 10-year melanoma-specific survival rates and their corresponding 95% confidence intervals (CIs), were analysed across substages. Cox regression models assessed the association between melanoma-specific survival and melanoma substages with hazard ratios (HRs) and 95% CIs calculated for both crude and adjusted models. The 10-year melanoma-specific survival rates among 5815 patients with stage II-III melanoma were as follows: IIA, 86%; IIB, 73%; IIC, 61%; IIIA, 78%; IIIB, 56%; IIIC, 43% and IIID, 19%. Patients with stage IIC melanoma (median age 70.0 years, 59.2% male sex) were older, more likely to be male, had more comorbidities (e.g. hypertension, type 2 diabetes) and lower socioeconomic status compared with patients with stage IIIA (median age 55.0 years, 51.5% male sex). Regression analyses revealed that differences in age, sex and thickness contributed to contrasting survival differences between stage IIC and IIIA, but a significant survival difference remained after adjusting for these factors. Patients in Sweden with localized stage IIC melanoma have significantly worse melanoma-specific survival than those with lymph node involvement in stage IIIA, with stage-specific differences in age, sex, comorbidities and socioeconomic status. These findings underscore the need for better treatment for thick, localized melanoma, and suggest reconsideration of current Swedish guidelines, which currently recommend that patients with stage IIC melanoma receive less intensive follow-up than those with stage IIIA.