2-cm versus 4-cm surgical excision margins for primary cutaneous melanoma thicker than 2 mm: a randomised, multicentre trial.

BACKGROUND Optimum surgical resection margins for patients with clinical stage IIA-C cutaneous melanoma thicker than 2 mm are controversial. The aim of the study was to test whether survival was different for a wide local excision margin of 2 cm compared with a 4-cm excision margin. METHODS We undertook a randomised controlled trial in nine European centres. Patients with cutaneous melanoma thicker than 2 mm, at clinical stage IIA-C, were allocated to have either a 2-cm or a 4-cm surgical resection margin. Patients were randomised in a 1:1 allocation to one of the two groups and stratified by geographic region. Randomisation was done by sealed envelope or by computer generated lists with permuted blocks. Our primary endpoint was overall survival. The trial was not masked at any stage. Analyses were by intention to treat. Adverse events were not systematically recorded. The study is registered with ClinicalTrials.gov, number NCT01183936. FINDINGS 936 patients were enrolled from Jan 22, 1992, to May 19, 2004; 465 were randomly allocated to treatment with a 2-cm resection margin, and 471 to receive treatment with a 4-cm resection margin. One patient in each group was lost to follow-up but included in the analysis. After a median follow-up of 6·7 years (IQR 4·3-9·5) 181 patients in the 2-cm margin group and 177 in the 4-cm group had died (hazard ratio 1·05, 95% CI 0·85-1·29; p=0.64). 5-year overall survival was 65% (95% CI 60-70) [corrected] in the 2-cm group and 65% (40-70) in the 4-cm group (p=0·69). INTERPRETATION Our findings suggest that a 2-cm resection margin is sufficient and safe for patients with cutaneous melanoma thicker than 2 mm. FUNDING Swedish Cancer Society and Stockholm Cancer Society.