Excision Margins of Melanoma Make a Difference: New Data Support an Old Paradigm

Excerpt

The surgical standard for the local treatment of a primary melanoma is a wide excision of the diagnostic biopsy site and/or residual intact primary lesion, inclusive of a surrounding margin of normal skin, en bloc with the underlying subcutaneous tissue including the superficial fascia. The rationale for such a surgical approach is to excise both the primary melanoma and any surrounding microsatellites in the lymphatics. Failure to excise both the primary and subclinical locally metastatic disease could result in a local recurrence (LR), which in reality is better termed “local metastasis.” Such events have been associated with melanoma mortality; therefore, the concern of inadequate surgery leading to LR and a risk of dying has been the underpinnings of the widely adopted paradigm that LR is both a function of primary tumor biology (tumor thickness and ulceration in particular) and extent of excision margin and that wider margins would be required for high-risk tumors.1‐3 If such a paradigm were true, then various outcome measures, including the frequency of local and regional recurrences, and possibly overall survival, would be impacted by the extent of excision margin, and in turn, the following assumptions or even conclusions could be made: (1) microscopic satellite disease is present more frequently with thicker (higher risk) melanomas and may have spread further from the periphery of the primary melanoma; (2) these microsatellites are a source of subsequent locoregional and distant relapse; and (3) wider margins more completely remove microscopic disease that would otherwise remain if narrower margins were used. This paradigm was tested formally in multiple, prospective, randomized, surgical trials across the entire spectrum of stage I and II thickness groups, comparing conservative margins (1 or 2 cm) to wider margins (3, 4, or 5 cm).4 Long-term results of these trials failed to demonstrate that a wider excision independently predicted melanoma-specific survival.4 One could conclude, and many have, that there is little evidence to support the paradigm and believe that any width of histologically clear excision margin is acceptable. …