Minimally invasive methods in pathomorphological assessment with a complete clinical response to neoadjuvant polychemotherapy in breast cancer patients

Purpose of the study. To evaluate and compare the diagnostic significance of vacuum‑ assisted biopsy (VAB) and multifocal trepan biopsy (MTB) methods based on a pathomorphological study of postoperative material in patients diagnosed with breast cancer (BC) in all molecular biological types after neoadjuvant polychemotherapy (NAPCT) with a complete clinical response (cCR). Patients and methods. The study included 70 patients with cT1–3N0–3M0 breast cancer with different molecular biological types after NAPCT. It was conducted at the P. Hertsen Moscow Oncology Research Institute – Branch of the National Medical Research Radiological Centre from 2021 to 2023. All patients underwent ultrasound and digital mammography before andafter NAPСT to assess the clinical response to treatment. MTB was performed in 35 patients, VAB in 35 patients, followed by surgical treatment. Histological findings obtained by VAB and MTB and surgical material were compared to assess the pathomorphological response of the tumor to treatment. Results. According to the pathomorphological conclusion, the following results were obtained during the VAB: 1 – truly positive, 29 – truly negative, 3 – falsely negative, 0 – falsely positive. The overall sensitivity of the technique was 25.0 % (CI 6.8–60.2 %); specificity – 100 % (CI 88.1–100 %); false negative result (presence of tumor cells in the surgical material and negative result of VAB) – 9.1 % (CI 3.4–20.2 %); false positive result (absence of tumor cells in the surgical material and a positive result of VAB) – 0 % (CI 0–10.6 %). The overall diagnostic accuracy of the method was 90.9 % (CI 79.8–96.6 %). According to the pathomorphological study, the following was obtained during the MTB: 1 – true positive, 17 – true negative, 5 – false negative and 0 – false positive results. The overall sensitivity of the technique was 16.7 % (CI: 4.3–45.9 %); specificity – (100.0 % CI: 80.5–99.9 %). The false negative result was 23.8 % (CI: 11.3–41.9 %). The false positive result is 0 %. The overall diagnostic accuracy of the method was 78.3 % (CI: 61.2–89.7 %). Conclusion. The results of the study indicate a higher sensitivity of the VAB method compared to MTB in assessing the pathomorphological response of breast cancer patients after antitumor drug treatment, which shows a vector for conducting large prospective studies of this method.