Pathologic examination of specimen after vacuum-assisted biopsy (VAB) in patients with breast cancer after neoadjuvant systemic therapy (NST).
Authors: Amirov Nikolay , Krivorotko Petr , Mortada Viktoriia , Artemyeva Anna , Smirnova Viktoriya , Emelyanov Alexander , Pesotskiy Roman , Yereshchenko Sergey , Tabagua Tengiz , Bondarchuk Yana , Enaldieva Diana , Ulrikh Daria , Levchenko Valerii , Channov Valentin , Kaygorodova Maria , Gorina Arina , Semiglazov Vladimir 
Published: June 2024

e12589 Background: VAB of the tumor bed in the breast has shown promising results as a minimally invasive method for determining pathologic complete response (pCR). A significant disadvantage of VAB is the fragmentation of the obtained material and the lack of methods for determining generally accepted predictive and prognostic factors such as RCB index in case if residual tumor is detected. Here we present a description of the accumulated experience of histological examination of specimens obtained using VAB in patients with breast cancer after NST. Methods: A single-center, prospective, non-randomized study included patients with unifocal breast cancer (cT1–2N0–1M0). Patients who achieved a complete clinical response (cCR) underwent VAB. VAB specimen intraoperatively was divided into «inner contour» (first 6-12 samples) and «outer contour» (latter 6-12 samples). Patients without signs of residual tumor (pCR, ypT0N0) did not undergo further surgical intervention. In case if residual tumor cells (RTC) were detected, standard breast surgery was performed. To assess an extent of tumor response to NST instead of RCB we used Miller-Payne system which has correlation with RCB. Results: 35 patients with a mean age of 48.3 (31–67) years were included in the analysis. Examination of VAB samples showed that 11 (31.4%) patients had a residual tumor, and in 24 (68.6%) patients no tumor cells were detected (ypT0N0). According to the Miller-Payne system, 28 patients had a complete pathological response, which corresponds to Miller-Payne = 5 and pathological stage ypT0/ypTis (24 patients ypT0N0, 3 patients ypTisN0 and 1 patient ypT0N1). In 7 patients with residual invasive tumor, the tumor response according to the Miller-Payne scale corresponded to grades 3 and 4. There was a statistically significant correlation between presence of RTC in the «outer contour» of VAB and presence of RTC in the postoperative histology after standard surgery (Х2 p=0.01, Fisher exact test p=0.048). In case when RTC were found in the «inner contour» no correlation with the presence of RTC in the postoperative histology after standard surgery was observed (Х2 p=0.292, Fisher exact test p=1.0). Radiologic-pathologic discordance was 25% for mammolymphoscintigraphy, 35.5% for US and 39.4% for mammography. In case if 3 of 3 studies after NST described cCR radiologic-pathologic discordance was 16.7%, in case if 2 of 3 studies described cCR it was 22.2% and in case if only 1 of 3 studies described cCR it was 27.3%. Conclusions: The method used to evaluate histological material allows us to obtain predictive and prognostic information necessary to clarify further treatment tactics in accordance with modern standards. It is necessary to conduct large-scale studies in this area to answer the question if this method can be used in routine clinical practice. Clinical trial information: NCT04293796 .