Although most primary cutaneous melanomas are treated with surgical excision alone, current international guidelines vary on the optimal size for the surgical margins, which can range from 1 to 3 cm. based on Breslow thickness. In the short term, wider excisions may be associated with greater risk of complications. Over the long term, they can be associated with neuropathic pain and poor cosmesis, often requiring reconstructive surgery — side effects that can diminish quality of life. That’s a significant concern for the majority of patients with stage 2 melanoma, who typically survive more than 10 years after diagnosis.

“Initially melanomas were treated with huge excisions — five centimeters in every direction,” says Shalana O’Brien, MD, Department of Surgical Oncology at Roswell Park Comprehensive Cancer Center. “But since the early ’90s, margins have been decreasing for melanoma, based on multiple trials.

“Currently in the U.S., for thin melanomas — less than one millimeter in depth — we take one-centimeter margins,” she explains. “For those between one and two millimeters in thickness, we take either one- or two-centimeter margins, and anything greater than two millimeters in thickness, we take a two-centimeter margin. These guidelines vary slightly throughout the world.”

But how will smaller excisions affect survival? Dr. O’Brien serves as principal investigator at Roswell Park for a randomized phase 3 clinical trial that aims to find out. It’s hoped that the results will help to better define the ideal margin size — one that will mitigate the impact on quality of life without increasing risk of recurrence. The trial, “Melanoma Margins Trial-II: 1cm v. 2 cm Wide Surgical Excision Margins for AJCC Stage II Primary Cutaneous Melanoma (MelMarT-II)” (NCT 03860883), is being conducted at 117 centers in the U.S. and abroad.

The trial grew from MelMarT, a feasibility study that compared the use of 1 cm. vs. 2 cm. surgical margins in 377 patients with primary melanomas having a Breslow thickness of greater than 1 mm. Results of that study provided the rationale for the current clinical trial, which has a target enrollment of 2,998 participants.

The clinical trial is enrolling patients with primary invasive cutaneous melanoma with a Breslow thickness greater than 2 mm. or ulcerated melanomas between 1-2 mm. in thickness. Half the patients will undergo wide local excision with a 1-cm.-wide excision, while the other half will have a 2-cm.-wide excision. Patients in both groups are required to undergo sentinel lymph node biopsy and may or may not undergo reconstruction.

The study will look primarily at the duration of disease-free survival, up to 60 months, from the time of randomization. Secondarily, it will measure the time to local or distant recurrence, to a maximum of 120 months; melanoma-specific survival, from randomization to melanoma-related death; and overall survival, from randomization to death from any cause. 

Patients also will be monitored for adverse postoperative events for 90 days post-surgery and will complete quality-of-life questionnaires at 3, 6, 12 and 24 months.

“Across many cancer types, we’re trying to de-escalate therapy if it is safe to do so,” notes Dr. O’Brien. “We don’t want to over-treat people, because there can be side effects related to more-extensive operations or treatments. We’re trying to give adequate treatment with less-invasive surgery.”