Mohs, Wide Excision Similar for Trunk-Extremity Melanoma

Melanoma of the trunk or extremity had similar survival whether treated with Mohs micrographic surgery (MMS) or wide local excision (WLE), a review of a national database showed.

Multivariable analysis of 5-year overall survival (OS) produced hazard ratios (HRs) that differed by less than 10% by surgery type for melanomas on the trunk, upper extremity, lower extremity, and all sites combined. Type of surgery did not emerge as a predictor of all-cause mortality in a separate multivariable analysis.

Despite the similar outcomes, WLE accounted for almost 98% of the 188,862 cases included in the review, Addison Demer, MD, of the University of Minnesota in Minneapolis, and coauthors reported in JAMA Dermatology.

“This finding is unsurprising, given existing data,” the authors noted. A previous review covering all anatomic sites reported better OS with MMS treatment of stage I tumors, but a subgroup analysis showed the benefit was limited to melanomas of the head and neck.

“These findings add to the existing body of evidence demonstrating that WLE is not associated with a greater survival benefit than MMS for treatment of cutaneous melanoma,” they concluded.

National Comprehensive Cancer Network (NCCN) guidelines favor WLE over MMS, “but in doing so lags behind the data in peer-reviewed literature which shows a clear advantage for MMS in the head and neck region in terms of both local recurrence rates and overall survival,” Naomi Lawrence, MD, of Cooper University Health Care in Marlton, New Jersey, told MedPage Today via email.

“As the Mohs procedure is performed with local anesthesia it is well tolerated by most types of patients,” she continued. “The most appropriate melanomas for Mohs would be located on the head, neck, genitalia, hands, feet; melanomas with significant radial component (2 cm or more — tend to have greater subclinical extension); or recurrent melanoma.”

Use of MMS remains controversial, Demer and coauthors acknowledged. Although NCCN and other guidelines have de-emphasized MMS, use of the procedure has increased in recent years, a trend that might be explained by a “robust and expanding body of data supporting its safety and efficacy for both in situ and invasive disease.”

Earlier this year, Demer and colleagues reported an improvement in OS for melanomas of the head and neck treated with MMS versus WLE. Another recent study showed a small OS advantage with MMS for stage I tumors. Demer and colleagues continued the investigation with an analysis to determine whether the benefits of MMS extended beyond early-stage melanomas and lesions on the head and neck.

The analysis included patients treated for any stage of melanoma of the trunk, upper extremities, or lower extremities from 2004 through 2015 and entered into the National Cancer Database. Data encompassed 188,862 cases of in situ and invasive melanoma. The patients had a mean age of 58.8, men accounted for 52.7% of the study population, and WLE was used in 97.7% of the cases.

Kaplan-Meier estimates showed better 5-year OS for patients treated with MMS (86.1% vs 82.9%, P<0.001). However, a multivariate analysis showed no difference in all-cause mortality for WLE versus MMS for melanomas of the:

• Trunk: HR 1.097 (95% CI 0.950-1.267)
• Upper extremity: HR 1.013 (95% CI 0.872-1.176)
• Lower extremity: HR 0.934 (95% CI 0.770-1.134)
• All sites combined: HR 1.031 (95% CI 0.941-1.130)

A separate analysis limited to invasive melanomas showed no significant differences in OS for any site.

Surgery type was not a predictor of OS. The only clinical factors associated with OS were positive surgical margins, higher Charlson-Deyo comorbidity score, tumor ulceration, and increasing Breslow depth.

A boxed summary of the article’s key points included the following interpretation of the findings: “Mohs micrographic surgery may be considered a reasonable treatment option for select T&E [trunk and extremity] melanomas; the absence of a survival benefit for Mohs micrographic surgery supports current U.S. practice patterns, where wide local excision is the predominant treatment for T&E melanoma.”

The main advantage of MMS is the higher cure rate in head and neck region because of comprehensive margin evaluation, said Lawrence, who is an expert for the American Academy of Dermatology. In addition, the tissue is processed via frozen section on the day of the procedure, so reconstruction does not occur until the margin is cleared. Finally, it is tissue conservative without sacrificing cure rate.

The main advantage of WLE is that it is quicker for the patient, as often the pathology is done in a delayed fashion and the patient does not have to wait in office for margin evaluation, she continued. However, WLE has a lower cure rate, particularly for tumors with higher risk of recurrence such as those on the head and neck. Additionally, as the margins are wider than MMS, the final scar may be larger.