Surgical margins and prognostic factors in patients with thick (>4mm) primary melanoma.

Background: Randomized trials have demonstrated the efficacy of 1- and 2-cm excision margins for thin and intermediate-thickness melanomas, respectively. The optimal margin of excision for thick melanomas is still unknown, however. We evaluated whether the margins used for intermediate-thickness melanomas can be applied safely to thicker lesions.
Methods: The charts of 278 patients with thick primary melanomas treated between 1985 and 1996 were retrospectively reviewed. Patients with distant metastases at presentation or with follow-up less than 6 months were excluded. Median follow-up was 27 months. Known melanoma prognostic factors and excision margins were evaluated for their impact on local recurrence (LR), disease-free survival (DFS), and overall survival (OS).
Results: Median tumor thickness was 6.0 mm, and 57% were ulcerated. At presentation, 201 patients (72%) were node negative and 77 (28%) were node positive (palpable or occult). The 5-year OS and DFS rates were 55% and 30%, respectively. The LR rate for all patients was 12%. Although nodal status, thickness, and ulceration were significantly associated with OS by multivariate analysis, neither LR nor excisional margin (<2 cm vs. >2 cm) significantly affected DFS or OS in these patients.
Conclusions: Because margins of excision greater than 2 cm do not improve LR, DFS, or OS compared to a margin of 2 cm or less, a 2-cm margin of excision is adequate for patients with thick melanoma. Because nodal status is a significant prognostic factor in these patients, staging by sentinel node biopsy should be considered in patients with thick melanomas and clinically negative nodal basins to allow proper entry and stratification in adjuvant therapy trials.