Local Recurrence and Survival in Patients With Melanoma >2 mm in Thickness at Difficult Sites Treated With 1-cm Versus 2-cm Margins.

Background: Melanoma guidelines recommend surgical excision with 2-cm margins for melanomas >2 mm in thickness. However, this procedure may be problematic at critical anatomic sites. We aimed to compare the outcomes of wide (2 cm) versus narrow (1 cm) excision margins in patients with melanoma >2 mm in thickness near critical structures.

Patients and methods: We retrospectively examined 736 patients undergoing excision with wide versus narrow margins at the National Cancer Institute in Milan, Italy, between 2001 and 2015.

Results: A total of 265 (36.0%) patients received a wide local excision-82 (30.9%) with linear repair and 183 (69.1%) with flap or graft reconstruction. A total of 471 (64.0%) patients received a narrow excision-320 (67.9%) with linear repair and 151 (32.1%) with flap or graft reconstruction (P<.001). The 10-year overall survival rate was 69.5% (95% CI, 63.3%-76.2%) in the wide group and 68.7% (95% CI, 63.8%-74.0%) in the narrow group (P=.462); 10-year crude cumulative incidence (CCI) of local recurrence was 5.4% (95% CI, 3.2%-9.2%) in the wide and 8.8% (95% CI, 6.4%-12.1%) in the narrow group (P=.150). Multivariable Fine-Gray modeling of the CCI of local recurrence showed that Breslow thickness (P=.010) was the only statistically significant parameter. Multivariable Cox models for overall survival showed that age (P<.001), Breslow thickness (P<.001), and sentinel lymph node status (P=.019) were statistically significant covariates. Excision margin was not a significant parameter affecting patients' outcome.

Conclusions: Wide local excision with 1-cm margins for melanoma >2 mm in thickness was not associated with an increased risk of local recurrence and did not affect overall survival.