Study suggests narrow excision margins safe in early melanoma resection

Current U.S., European, and Australian guidelines recommend 10-mm safety margins for radical excision of primary melanomas, but for patients with early-stage cutaneous melanoma in critical areas of the body, excision with 5-mm margins may not significantly increase risk for recurrence or melanoma-specific mortality (MSM), results of a retrospective study suggest.

Among 1,179 patients with stage T1a melanomas near the face, scalp, external genitalia, or other critical areas, the weighted 10-year local recurrence rate for patients who underwent resection with 10-mm margins was 5.7%, compared with 6.7% for those who had resections with 5-mm margins, a nonsignificant difference.

Weighted 10-year melanoma-specific mortality was 1.8% for patients treated with wide margins, vs. 4.2% for those treated with narrow margins, also a nonsignificant difference. Patients treated with narrow margins did have significantly fewer reconstructive surgeries than patients treated with wide margins, reported Andrea Maurichi, MD, and colleagues at the National Cancer Institute of Italy in Milan.

“Because this association was found in melanomas of the head and neck, acral, and genital sites, there is no plausible reason why it could not be extrapolated to other locations. The findings also support the need for prospective randomized clinical trials to definitively answer the important question about appropriate excision margins for T1a melanoma,” they wrote in the study, published online in JAMA Dermatology.

The authors also found, however, that Breslow thickness greater than 0.4 mm and mitotic rate greater than 1/mm­­² were associated with worse MSM, and that acral lentiginous melanoma, lentigo maligna melanoma, and increasing Breslow thickness were associated with a higher incidence of local recurrence.

A melanoma expert who was not involved in the study said that despite these findings, wider margins are always preferable.

“There is always a conversation around these general [critical] areas, but as a rule we try to get larger margins,” said Ryan J. Sullivan, MD, of Mass General Cancer Center in Boston.

In an interview, Dr. Sullivan said that the finding about lower frequency of reconstructive procedures in the narrow margins groups may be more of a concern for younger patients than for the elderly.

Study design

The investigators conducted a retrospective cohort study of consecutive patients aged 18 or older at the National Cancer Institute of Milan who were diagnosed with T1a cutaneous melanoma close to critical areas from 2001 through 2020.

Patients with primary cutaneous melanoma of the head and face areas with functional or cosmetic considerations, acral areas (plantar, palmar, digital and interdigital areas), external genitalia, or periumbilical and perineal areas were eligible for inclusion.

The cohort comprised 1,179 patients with a median age of 50 and equal sex distribution. Of these patients, 626 (53%) had a wide excision, of whom 434 had a linear repair, and 192 had a flap of graft reconstruction. The remaining 553 patients had narrow excisions, 491 with linear repair, and 62 with flap or graft reconstruction.

Analyses were adjusted to account for imbalances between the surgical groups.

The study was supported by the nonprofit foundation Emme Rouge. The authors and Dr. Sullivan reported having no relevant conflicts of interest to disclose.