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Negative biopsy margins in SCC, BCC produced different results

Negative biopsy margins of squamous cell carcinomas produced subsequent excisions free of residual tumor, while negative biopsy margins of basal cell carcinomas were not predictive in a recent study.

Two hundred thirty-five nonmelanoma skin cancer (NMSC) biopsies and subsequent excisions from 216 patients were included in the retrospective study. The biopsies revealed 148 (63%) squamous cell carcinomas (SCC) and 87 (37%) basal cell carcinomas (BCC).

Following standard bread-loafing excision, researchers evaluated deepest histologic level of excision, presence or absence of residual tumor, presence of previous biopsy site changes and presence of curettage.

Fifty-six SCC tumors (38%) and 61 BCC tumors (70%) showed residual tumor present in the corresponding excision (P<.0001).

Twenty-one biopsies (12 SCC, nine BCC) had negative lateral and deep margins. The SCC biopsies (8.1%) with negative margins had no residual tumor present in corresponding excisions. Six were well differentiated, five were keratoacanthoma subtype and one was in situ. The negative-margin BCC biopsies (10.3%) included seven (77.8%) with residual tumor present upon subsequent excision. Among them, five were nodular, one was pigmented nodular and one was superficial.

The researchers cautioned that while statistical analysis “reached significance,” the 21 biopsy specimens with negative margins were a small sampling.

“Negative-margin diagnostic biopsies may be therapeutic for well-differentiated or keratoacanthoma subtypes of [SCC] because all subsequent excisions were devoid of tumor,” the researchers wrote. “Negative biopsy margins from [BCC] were not predictive of tumor removal."