What are the recommended surgical margins in the surgical treatment of cutaneous melanoma?

Updated: Oct 13, 2020
  • Author: Susan M Swetter, MD; Chief Editor: Dirk M Elston, MD  more...
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Answer

The narrowest efficacious margins for cutaneous melanoma have yet to be determined. Surgical margins of 5 mm are currently recommended for melanoma in situ, and margins of 1 cm are recommended for melanomas less than or equal to 1 mm in depth (low-risk primaries). [126] In some settings of melanoma in situ, tissue sparing may be critical, and Mohs margin-controlled excision may be appropriate. A 2012 prospective study of 1120 melanoma in situ cases revealed that Mohs surgery, with 9-mm margins of normal-appearing skin around the melanoma, resulted in complete removal of almost 99% of lesions and was superior to 6 mm margins, which cleared only 86% of all tumors. [127] However, Mohs surgery is not recommended in either the NCCN or AAD melanoma guidelines for surgical resection of invasive cutaneous melanoma.

Randomized prospective studies show that 2-cm margins are appropriate for tumors of intermediate thickness (1-4 mm Breslow depth), although 1-cm margins have been proven effective for tumors of 1- to 2-mm thickness. [128, 129] Margins of 2 cm are recommended for cutaneous melanomas greater than 4 mm in thickness (high-risk primaries) to prevent potential local recurrence in or around the scar site.

A 2004 prospective study of melanoma greater than or equal to 2 mm thickness (median depth 3 mm) from the United Kingdom suggested that narrower margins (1 cm) result in higher locoregional recurrence compared with wider margins (3 cm), although no difference was noted in melanoma-specific survival between the two groups. [130] However, this study was criticized for combining satellite, in-transit, and regional nodal recurrences as the primary endpoint and by excluding SLNB (which would have demonstrated existing occult regional nodal metastasis at the time of wide local excision). Likewise, because a 2-cm margin is as efficacious as a 4-cm margin for melanomas of 1-4 mm depth, a 3-cm margin has been deemed unlikely to prove more beneficial than a 2-cm margin.

A retrospective study of high-risk primary melanomas (>4 mm thickness, median depth 6 mm) showed that excisional margins greater than 2 cm have no effect on local recurrence, disease-free relapse, or OS rates; therefore, a 2-cm margin is likely appropriate in this subgroup. [131]

In a recently concluded multicenter randomized controlled trial in 9 European countries from 1994 to 2002, 936 patients with clinical stage IIA–C cutaneous melanoma thicker than 2 mm were allocated 1:1 for wide excision with either 2- or 4-cm resection margin. With median follow up of 6.7 years, the overall 5-year survival in both groups was 65%, suggesting that a 2-cm resection margin is sufficient and safe for patients with cutaneous melanoma thicker than 2 mm. [132]

Mohs micrographic surgery has also been proposed for cutaneous melanoma and has the advantage of providing visualization of 100% of peripheral and deep margins microscopically. While studies have shown no increased local recurrence for Mohs surgery compared with historical controls, much of the data stem from thinner tumors with a lower risk of local recurrence and metastasis. [133] Mohs surgery may have certain "niche" indications, including melanomas located the head, neck, hands, or feet. Mohs surgery may prove useful in completely removing subclinical tumor extension in certain subtypes of melanoma in situ, such as lentigo maligna and acral lentiginous melanoma in situ.


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