The authors call for "protocolization" of facility practices to help reduce survival differences between centers.
"Uniform practices need to be data driven," Dr. Sean Christensen of Yale University School of Medicine in New Haven told Reuters Health by email. "There are several potential variations in the practice of MMS for melanoma, including the size of the surgical margin excised in the initial stage of MMS; the way excised tissue is processed for intraoperative histologic evaluation; the use of immunostains to identify melanoma microscopically; the criteria used to distinguish melanoma from benign melanocytes microscopically; and whether formalin-fixed sections are obtained for additional pathologic evaluation after MMS is completed with frozen sections."
"At this point," he said, "we do not have enough information to know which practices produce optimal outcomes, or even which of these variables are significant in impacting outcomes."
The team's study, published in JAMA Dermatology, showed significant interfacility variation in overall survival post-MMS. The finding came from an analysis of data from more than 4,000 patients (median age, 60; 55% men; 96% non-Hispanic white) with early, non-metastatic melanoma treated at 462 U.S. centers from 2004-2014.
Sixty-two centers (13%) were top decile-volume facilities (TDVFs; eight or more annual cases) that treated 2,513 patients (62%). The majority of TDVFs were academic institutions (60%).
On multivariable analysis, treatment at an academic center was associated with a nearly 30% reduction in hazard of death (hazard ratio, 0.73; 95% confidence interval, 0.596 to 0.895).
A separate analysis showed that treatment at TDVFs also was associated with significantly improved survival (HR, 0.80).
"Presumably, higher-volume facilities and academic facilities are performing MMS in a fashion that optimizes outcomes, but additional study will be needed to define what specific practices have the most important effect on outcomes," Dr. Christensen noted. "Once we have that data, we can begin to make recommendations about standardizing treatment practices."
Dr. Richard Torbeck, assistant professor at The Icahn School of Medicine at Mount Sinai and director of Skin Cancer Surgery at Blavatnick Family Chelsea Medical Center in New York City, told Reuters Health by email that there are "a lot of technical difficulties" with MMS for melanoma that are not seen in basal-cell or squamous-cell carcinoma.
With regard to slide preparation, he said, "a histotechnician who is not knowledgeable or does not create MMS for melanoma on a regular basis can have difficulty with the complex and time-consuming immunohistochemistry (IHC) protocols. Once the slides are prepared, a surgeon who does not read melanoma slides with IHC with regular frequency may not pick up on subtle issues like chronic sun damage, or artifacts that can lead to false positives or false negatives."
Currently, he said, many Mohs surgeons do not provide MMS for T1a-T2a melanomas "due to lack of exposure in their training and the lack of standardization of slide preparation and reading protocols/techniques. Additionally, patient selection can be limited, as shown in the study, with only 23,000 treated by MMS out of 525,000 patients with T1-T2a melanoma."
"Academic centers with a high volume of cases are more likely to have patient therapeutic pathways that involve multidisciplinary work-up and care," said Dr. Torbeck, who was not involved in the new study. "When these care pathways are in place, we can have a better concept of the staging, prognosis, and treatment."
SOURCE: https://bit.ly/3dBciuI and https://bit.ly/31Nngrs JAMA Dermatology, online March 31, 2021.
By Marilynn Larkin
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