Conference Coverage

Total margin control surgery warranted for high-risk keratinocyte carcinomas



– A recent meta-analysis found that total margin control surgery substantially cut the risk of recurrence in patients with high-risk keratinocyte carcinomas, Chrysalyne Schmults, MD, said at the World Congress of Dermatology.

While standard excision will cure the vast majority of low-risk basal cell carcinoma (BCC) or squamous cell carcinoma (SCC), those classified as high risk are best treated with the advanced surgical procedure, also referred to as circumferential peripheral and deep margin assessment (CCPDMA), said Dr. Schmults, director of the Mohs and Dermatologic Surgery Center at Brigham and Women’s Hospital in Boston.

For high-risk cases, CCPDMA has superior outcomes, compared with standard excision, according to results of the meta-analysis conducted by Dr. Schmults and colleagues. The meta-analysis has not yet been published.

The recurrence rate for carcinomas with perineural invasion – a high-risk feature – was 23.28% for standard excision, but just 9.74% for CCPDMA in the meta-analysis of medical literature from 1993 to 2017.

“This is a really big drop,” Dr. Schmults said. “If you do total margin control surgery on your perineural invasive cases, you’re going to drop your recurrence rate by two-thirds, and that’s a really big difference.”

For carcinomas without perineural invasion, the recurrence rate is about 4.5% for standard excision and about 2.0% for CCPDMA, the analysis showed. “That’s a difference, but it’s not a big enough difference that we’re going to start doing total margin control surgery on every single basal cell and squamous cell carcinoma that comes to us,” Dr. Schmults commented.

Using techniques such as Mohs surgery that allow for CCPDMA, nearly 100% of the surgical margin can be seen; by contrast, standard histology allows for visualization of only about 1% of the marginal surface, according to Dr. Schmults.

While CCPDMA may have superior outcomes for high-risk keratinocyte carcinomas, defining what constitutes high risk remains a challenge, particularly for patients with BCCs. “We don’t have good literature on which are the rare, bad basal cells,” she said.

But more clarity may be on the way. In a paper under review for publication on Brigham and Women’s Hospital (BWH) staging criteria for BCC, Dr. Schmults and colleagues describe a subset of patients with BCC at higher risk of metastasis and death based on specific high-risk tumor characteristics.

High risk is better defined for SCCs. According to the BWH classification system for cutaneous SCCs, developed by Dr. Schmults and colleagues, high-risk features include larger tumor diameter, poorly differentiated histology, perineural invasion, and tumor invasion beyond subcutaneous fat or to bone.

Patients with SCC classified as high stage by the BWH system have about a 25% risk of metastasis or death. “These patients really need that total margin control surgery,” Dr. Schmults said.

High-stage SCC patients who did not get Mohs surgery in a study (J Clin Oncol. 2014 Feb 1;32[4]:327-34) conducted by Dr. Schmults and her associates, had a quadrupling in risk of death from disease, compared with those who did get the procedure in a more recent study (J Am Acad Dermatol. 2019 Mar;80[3]:633-8).

“These are fairly small studies,” she pointed out. But the large meta-analysis she presented at the meeting showed the same result, “that the higher the stage, the worse your tumor is, and whether it’s basal cell or squamous cell, the greater the advantage for total margin control surgery.”

Dr. Schmults reported that she is the panel chair for the National Comprehensive Cancer Network guidelines on nonmelanoma skin cancer, and that she was a cutaneous SCC committee member for the 8th edition of the American Joint Committee on Cancer cancer staging system. She also participated in the development of the BWH staging system for SCC.

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