Wide Local Excision

CRITICAL ELEMENTS

Margin Width
Depth of Excision
Anatomic Orientation of the Excision

1. MARGIN WIDTH

Recommendation: The margin width for wide local excision of melanoma is based on the Breslow thickness of the primary tumor. Margin width should be 1 cm for melanomas <1 mm thick, 1 or 2 cm for melanomas 1 to 2 mm thick, and 2 cm for melanomas <2 mm thick. The margin width for wide local excision of a melanoma in situ should be 5 mm. Standard wide local excision margin recommendations also apply to melanomas of the skin of the digits. Subungual melanoma frequently requires amputation of a distal phalanx.

Type of Data: Melanoma randomized controlled trials; observational studies in subungual melanoma in situ.

Grade of Recommendation: Strong recommendation, high-quality evidence; subungual melanoma: weak recommendation, high-quality evidence.

Rationale

The purpose of melanoma wide local excision (WLE) is to obtain local control by removing the primary tumor as well as the local at-risk subcutaneous lymphatics. The margin is measured circumferentially at the level of the skin from either residual gross tumor and/or the previous biopsy scar.

The recommended WLE margin for melanoma in situ (MIS), according to a 1992 National Institutes of Health consensus panel, is 5 mm (Table 8-1).¹ This measure is not based on randomized trial results or any prospective data. In some particular MIS
subtypes, such as lentigo maligna melanoma, that may have subclinical extension, 1-cm margins may be needed to obtain negative margins.²

TABLE 8-1 Recommended Wide Local Excision Margins for Primary Melanoma Based on Breslow Thickness

Thickness of Melanoma (mm)	Measured Surgical Margin Width (cm)	Strength of Recommendation	Evidence
Melanoma in situ	0.5	Weak	Consensus
<1.0	1	Strong	RCT
1.0-2.0	1 or 2	Strong	RCT
<2.0	2	Strong	RCT
RCT, randomized controlled trial.

For melanomas <1.0 mm thick, the recommended WLE margin is 1 cm. For melanomas 1 to 2 mm thick, the recommended margin width is 1 or 2 cm. This recommendation is based on results from a World Health Organization RCT, where patients with melanomas up to 2 mm thick were randomly assigned to WLE with 1- or 3-cm margins.^3,4 At follow-up 10 years later, local recurrence rates and survival were comparable between the two groups. RCTs conducted by the Swedish Melanoma Study Group and French Cooperative Group compared margins of 2 cm and 5 cm and found no significant difference in either local recurrence or overall survival.^5,6

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