Evaluation of Accuracy of Side Surgical Margins for Basal Cell Carcinoma Determined as Dermato-Oncologists

Abstract

In Japanese patients, most basal cell carcinomas (BCCs) have pigmentation therefore, it is relatively easy to evaluate the tumor borders. We often determine narrower side margins than the current Japanese BCC guidelines. The aim of this study is to evaluate the accuracy of side margins in patients with BCC which was determined by their dermato-oncologist and to clarify the appropriate side margins for Japanese patients with BCC. We retrospectively analyzed 282 BCC specimens between 2008 to 2017 in our institution. The maximum distance differences obtained by subtracting the histological distance from the tumor border to the side edge from the preoperative side margins were measured as "accuracy gaps" of side margins. Based on the accuracy gaps, the histograms were drawn and the estimated negative margin rates (ENMRs) with narrower (2- and 3-mm) side margins were calculated. The ENMRs were 95.3% in 2 mm side margins and 98.2% in 3 mm side margins. Subgroup analysis indicates that high ENMRs will be obtained with 2-mm in low-risk group and 3-mm side margins in tumors with poorly-defined clinical borders, non-pigmented subtype and aggressive clinical subtype.