Too far.

One rule of thumb for the optimal excision margin for cutaneous melanoma is that the margin in centimeters should roughly mirror the tumor thickness in millimeters. That means thicker lesions can call for quite large margins. The 5 year results of a multicenter trial support the current recommendation for a maximum 2 cm excision margin for any melanoma is thicker than 2 mm. Here, we have its long-term results. This trial randomized nearly 1000 patients with 2 mm or thicker melanomas located on the trunk or extremities to either a 2 or 4 cm resection margin. Importantly, this was in the days prior to immunotherapy. With a median follow up of close to 20 years, there was no improvement in overall or melanoma-specific survival with wider (>2 cm) resection margins. Perhaps more sobering from is the ~50% rate of melanoma-related deaths with longer follow-up.TBL: An excision margin of 2 cm is just as good as larger margins for thick (>2 mm) melanomas on the trunk or extremities, and even that is probably overkill for the face. | Utjes, Lancet 2019