2‐mm surgical margins are adequate for most basal cell carcinomas in Japanese: a retrospective multicentre study on 1000 basal cell carcinomas

Abstract

Background Surgery is the gold standard for basal cell carcinomas (BCC). Current recommended surgical margins for BCCs are determined from studies in Caucasian populations. However, the appropriate surgical margins for BCCs in non‐white races are unclear. Objectives To investigate the accuracy of preoperative determination of clinical tumour borders and appropriate surgical margins in Japanese patients with BCC. Methods The maximum calculated differences in distance between the preoperatively determined surgical margins and the actual histologic tumour side margins were considered as ‘accuracy gaps’ of clinical tumour borders. Estimated side margin positivity rates (ESMPRs) with narrower (2 and 3 mm) surgical margins were calculated on the basis of the accuracy gaps. Results Overall, 1000 surgically excised BCCs from 980 Japanese patients were included. The most frequent histologic subtype was nodular BCC (67%). The median accuracy gap was 0.3 mm [interquartile range (IQR): −0.5 to +1 mm]. The ESMPRs with 2‐ and 3‐mm surgical margins were 3.8% and 1.4%, respectively. Only the ESMPRs between the well‐defined (n = 921) and poorly defined clinical tumour border groups (n = 79) showed statistical difference [2‐mm margin: 3.1% vs. 11.7%, OR: 3.89, 95% confidential interval (CI): 1.41–10.71, P <0.01; 3‐mm margin: 0.97% vs. 6.3%, OR: 6.58, 95% CI: 1.67–25.99, P <0.01]. No significant differences in ESMPRs were noted in other subgroups including risk classifications. Conclusions The determined clinical tumour border accuracy gaps in this Japanese cohort were negligible. Dermatologic surgeons may use narrower surgical margins with acceptable margin positivity rates. The clarity of clinical tumour borders could be an appropriate guide for selection of different surgical margins in the Japanese cohort.

Evidence from Clinical Studies Related to Dermatologic Surgeries for Skin Cancer

“…The disadvantages of MMS include its being cost- and time-consuming [ 32 ]. In addition, MMS requires specialized equipment and a trained technician, and therefore, this type of surgery is not universally available [ 33 , 34 ]. Multiple studies suggested the usefulness of MMS for the treatment of melanoma.…”

“…Nakamura et al conducted a retrospective multicenter study of 1000 BCC lesions treated with WLE. In their study, the most common peripheral surgical margin was 3 mm (52%), followed by 2 mm (26%) and 5 mm (11%), and 12 lesions showed a positive surgical margin [ 34 ]. The authors evaluated the “accuracy gap” of the clinical tumor border by calculating the difference in the distance between the clinically determined peripheral surgical margin and the histologic tumor side margin, and they also calculated the estimated margin positivity rates (ESMPRs) by the accuracy gap.…”

Concordance in judgment of clinical borders of basal cell carcinomas in Japanese patients: A preliminary study of JCOG2005 (J‐BASE‐MARGIN)

“…2 In contrast, most BCC in Asians develop as pigmented lesions (52.4%-90%) [2][3][4] with well-defined clinical borders. 5 Surgical excision of tumors with negative margins is the standard of care for most BCC. The surgical margins are classified as high or low risk based on multiple risk factors for recurrence, including the tumor location/size, clarity of clinical borders (welldefined or poorly defined), primary or recurrent tumor, status of immunosuppression, history of radiotherapy, pathological subtype, and perineural involvement.…”

“…In addition, the clarity of clinical borders could be a more reliable measure to determine the width of surgical margins than the risk classifications of BCC in Japanese. 5 Based on these data, we are currently conducting a non-randomized, prospective trial (Japan Clinical Oncology Group…”

“…BCC in Caucasian populations often develop as non‐pigmented lesions with poorly defined clinical tumor borders (clinical borders) 2 . In contrast, most BCC in Asians develop as pigmented lesions (52.4%–90%) 2–4 with well‐defined clinical borders 5 …”