Abstract P4-13-03: Effect of intraoperative imprint cytology followed by frozen section for margin assessment in breast-conserving surgery

Purpose: In patients undergoing breast-conserving surgery (BCS) for breast cancer, the positive margin rate has reportedly reduced from 15%-50% to 6%-19% by the addition of intraoperative margin assessment (IMA). Previous reports have suggested that imprint cytology (IC) is superior to frozen section (FS) because the former can assess the entire circumference of surgical margins, although its precision is inferior to that of FS. In contrast, FS cannot evaluate the entire circumference of surgical margins and may result in sampling errors in the detection of positive margins. To date, reports on IMA have described only the single use of IC or FS. Therefore, the purpose of the present study was to elucidate the effect of IC followed by FS for IMA in BCS by comparing the positive margin rate with that of permanent section (PS). Patients and Methods: We enrolled a total of 522 cases which underwent BCS without neoadjuvant therapy between January 2013 and April 2019. The entire circumference of surgical margins was subjected to IC. Upon obtaining negative IC results, no other procedure was added for IMA. FS was only added for the cases with “positive” or “suspicious” IC results. We performed additional intraoperative excision for FS-positive sites of lesions and did not add any procedure for IMA. All margins were evaluated by postoperative PS after excision. We defined “PS positive” as the exposure of cancer cell for invasive ductal carcinoma and close margin less than 2 mm for non-invasive ductal carcinoma (DCIS) based on the Society of Surgical Oncology and American Society of Radiation Oncology guidelines (2014/2016). Cases diagnosed as IC positive but not subjected to additional intraoperative excision based on FS-negative findings were defined as “IC false positive.” We then compared the results of PS with those of IC and FS. In addition, we evaluated the association between clinicopathological factors and PS-positive or IC-false-positive diagnosis by univariate and multivariate analyses. Results: Of 522 cases, 136 (26.1%) were IC positive and 386 (73.9%) were IC negative. Among the 386 cases not subjected to FS for IMA because of IC-negative diagnosis, 11 (2.8%) were PS positive. In 47 (34.6%) of 136 IC-positive cases, additional intraoperative excision was unnecessary due to FS-negative diagnosis. Postoperative PS revealed that all of these 47 cases were PS negative. Although we performed additional intraoperative excision, 5 cases remained PS positive. There was no association between PS-positive diagnosis and clinicopathological factors. In univariate analysis, premenopausal status and DCIS significantly increased the IC-false-positive diagnosis risk (p Citation Format: Tamaki Tamanuki, Maki Namura, Tomoyoshi Aoyagi, Tomoko Suwa, Shinichirou Shimizu, Hiroshi Matsuzaki. Effect of intraoperative imprint cytology followed by frozen section for margin assessment in breast-conserving surgery [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-13-03.