Long term results support 2cm surgical excision margins for thick melanomas

Skin cancers

By Michael Woodhead

18 Jul 2019

Prof John Thompson

A 20-year follow up study has provided reassurance that 2cm surgical excision margins are appropriate for thick primary melanoma.

Results from a Scandinavian study found no difference in melanoma specific or all cause mortality outcomes between patients who had  2cm or a 4cm excision margin for a primary cutaneous melanoma thicker than 2mm.

Published in the Lancet, the findings come from a randomised controlled trial that recruited 936 patients in the 1990s to have excision of a localised melanoma of greater than 2mm thickness.

At a median overall follow-up of 19·6 years, mortaility rates were 49% in the 2cm excision margin group and 51% in the 4cm group (unadjusted Hazrad Ratio 0·98).

Of the 397 deaths attributed to cutaneous melanoma, 192 (48%) were in the 2cm excision margin group and 205 (52%) in the 4cm excision margin group (unadjusted HR 0·95).

“To our knowledge, this is the longest follow-up of outcome following surgery for thicker melanoma (>2 mm),” wrote the study authors.

The findings were welcomed by Professor John Thompson, Senior Surgeon at the Melanoma Institute of Australia, Sydney, who wrote in an accompanying commentary that “it can now safely be concluded that surgical excision margins greater than 2 cm are not required for melanomas greater than 2 mm in Breslow thickness.”

“Radical excisions with margins exceeding 2 cm in such patients, which potentially cause substantial morbidity and place a great burden on health-care systems, can confidently be considered obsolete,” he said.

Professor Thompson said the question to be answered now is whether narrower 1cm excision margins might be safe for thicker melanomas.

This would be answered by the Australia and New Zealand MelMarT trial, that has just started, and which aims to compare 1-cm margins with 2-cm margins for melanoma with thickness 1 mm or greater in 3000 patients.

It will be several years before the results of this trial are available, but for now, based on the updated results of the trial reported by Utjés and colleagues, we can be reassured that excision margins of 2 cm are safe, even for patients with thicker melanomas.

Current Australian guidelines recommend 1–2 cm margins for melanoma of 2-4mm thickness and 2cm margins for melanoma >4mm thick.

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