96P Intraoperative radiological control of resection margins after neoadjuvant systemic therapy in breast-conserving surgery in patients with breast cancer

The «purity» of the examined edges of the resected breast tissue is the main indicator of the reliability of the breast-conserving surgery (BCS) and one of the main factors in the development of local recurrence. Neoadjuvant systemic therapy (NST) allows evaluating the effectiveness of therapy in vivo and reducing the size of the initial formation, both in locally advanced and resectable forms of breast cancer with further BCS. Currently, one of the promising methods for intraoperative assessment of the status of resection margins BCS is X-ray control using various devices. 142 performed BCS after NST were analyzed. All removed sectoral specimens were intraoperatively transported to the histology unit for X-ray assessment of resection margins using the Faxitron PathVision apparatus, and 61 specimens were transported to the X-ray Department for examination on the Senographe mammography unit. After the result of the x-ray, the surgeons completed the BCS and the samples were sent for a planned histological examination. The average execution time was 7 minutes for the Faxitron PathVision and 10 minutes for the Senographe mammography device. Of the 142 studied anatomical preparations after BCS, a positive resection margin was found in 4 (2.7%) cases (false negative result) in 2 patients a high X-ray density of breast tissues was noted. In 3 patients, the positive resection margin was represented by residual DCIS, in 1 case by invasive cancer. A true positive result was detected in 5 cases, a false positive result in 2 patients. Also, in 46 (32.3%) patients, metal marks were detected, which were placed before the start of NST, the resection margins were intact. The main advantage of NST is the ability for surgeons to perform breast-conserving surgery to improve patients' quality of life and aesthetic outcomes without compromising disease-free and overall survival. Intraoperative X-ray control of resection margins during BCS provides a quick and complete assessment of the relationship of the tumor to resection margins, including the presence of microcalcifications in the removed sample, visualization of metal marks established before the start of NST.