Abstract PO2-28-11: How to improve margins in breast cancer surgery: a

Abstract Objective: Intraoperative specimen mammography (ISM) is a diffuse technique that allows surgeons to check specimens immediately after lumpectomy, instead of intraoperative frozen sections, definitely abandoned. in Italy and Europe, because it is regarded as too expensive and time-consuming examination. Although the specimen is slightly compressed, the radiological image can be distorted by tissue overlap, and this may affect the evaluation of tumor borders, resulting in extension of the lumpectomy. As ISM may be less precise due to inadequate compression, a vacuum effect was applied to the specimen to increase the precision of margin detection. Study design: This study was conducted at St. Anna Hospital Breast Unit, Turin, Italy. Women who underwent lumpectomy for cancer were eligible for inclusion. BCS resection was performed with a free margin, and the surgical specimen was imaged immediately by SSM and evaluated by an expert radiologist and surgeon.Inclusion criteria were: breast cancer detected by a screening test, and treatment with surgical lumpectomy. Both standard ISM (sISM) and vacuum ISM (vISM) were performed. A dedicated breast surgeon at the study institution performed both surgery and radiological scans, and their interpretation. A dedicated radiologist reviewed all of the images. ISM was performed by a digital specimen mammography system (Faxitron, Bioptics Inc., Tucson, AZ, USA) in the operating room. Specimen registration and ISM analysis took 3 min. sISM (two orthogonal projections) was performed. Specimens were sealed in plastic bags in the vacuum apparatus (TissueSAFE Milestone Medical, Sorisole, Italy); this process took a few seconds. 152 specimens obtained after lumpectomy from 1 April 2021 to 31 April 2022 were scanned. sISM (two orthogonal projections) was performed. Next, the specimen was placed in a vacuum bag, and vISM was performed. Additional tissue was removed if the surgeon considered that excision was inadequate. Finally, the specimen was sent for definitive histopathological analysis, which is the gold standard for the assessment of surgical margins. Intraoperative histological margin assessment was not performed. The sISM and vISM images and final histopathology reports were compared. A first experience on a limited number of patients to demonstrate feasibility of the technique, is reported in table 1 and 2. Results: For sISM, specificity was 43,85% 95 % confidence interval (CI) 35.96-51.73, sensitivity was 40.91% (95 % CI 33.09-48.73), positive predictive value (PPV) 10.98% (95 % CI 6.01-15.95) and negative predictive value (NPV) 81.43% (95 % CI 75.25-87.61). For vISM, specificity 92,31% (95 % CI 88,07-96.54), sensitivity 72.73% (95 % CI 65.65-79.81), PPV 61.54% (95 % CI 53.80-69.27) and NPV 95.24% (95 % CI 91.85-98.62). Conclusion: ISM is a valid, safe and quicker alternative to intraoperative histopathological study, but has been reported to be limited due to less compression than standard SSM. Consequently, ISM may result in a high percentage of false-positive results, meaning unnecessary wider resections that lead to increased operative times and worse aesthetic results. A vacuum effect was performed on the specimen to increase the precision of margin detection. vISM images seem to be easier to interpret than sISM images (Figs. 1–3) as they are characterized by a vacuum-created radiolucent rim that better defines the tumor margins. These data suggest that the vacuum technique is feasible, cost-saving and yields results that are similar to those from frozen sections but without the limitations, such as prolonged operating time, high variability in sensitivity due to pathologists abilities, risk of compromising the histology, and unreliability for small lumps and ductal carcinoma in situ. Keywords: Breast cancer; Intraoperative mammography; Lumpectomy; Specimen mammography; Vacuum intraoperative mammography. Table 1. Clinical Data IC, invasive cancer; DCIS ductal carcinoma in situ; ADH, atypical ductal hyperplasia; ILC, invasive lobular cancer; B3, lesions of uncertain malignant potential; IMPC, invasive micropapillary carcinoma; NST, no special type; sISM, standard intraoperative specimen mammography; vISM, vacuum intraoperative specimen mammography. ª Margin: 0, involved; 1, free Table 2. Figure 1 - 2 - 3 Standard intraoperative specimen mammography (left) and vacuum intraoperative specimen mammography (right). Citation Format: Maria Grazia Baù, Vincenzo Marra, Alessandra Surace, Donatella Tota, Maria Piera Mano, Aurelia Mondino, Alessandro Bottero, Elisabetta Robba. How to improve margins in breast cancer surgery: a abstract. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-28-11.