The diagnostic accuracy of 12-point core biopsy of a tumor bed compared to the study of surgically obtained breast tissue in patients with locally advanced triple-negative or HER2-positive breast cancer after neoadjuvant systemic and targeted therapy.

Abstract

e12097 Background: Innovative advances in neoadjuvant systemic and targeted breast cancer therapy implicate surgical treatment in specific patient groups can be avoided. The core biopsy of the tumor bed and some diagnostic approaches (breast ultrasound, mammography, SPECT/CT) allow for precise evaluation of the treatment efficacy. Methods: This research started in our department in 2018, we picked two groups of 15 patients each treated for locally advanced TNBC or grade cT1-4N1-3M0 HER2-positive breast cancer: HER2+/ER+ or HER2+/ER- breast cancer. The TNBC group received 6 cycles of NACT of paclitaxel combined with doxorubicin and carboplatin AUC5. The HER2+ group received 4 cycles of АС polychemotherapy followed by 4 cycles of monochemotherapy with the docetaxel and 3-weekly trastuzumab. The HER2+ group is receiving adjuvant trastuzumab for up to one year, where ER-positive patients are also given hormone therapy with tamoxifen or aromatase inhibitors. The response to neoadjuvant treatment was assessed in all patients using standard two-dimensional mammography, ultrasound elastography, and SPECT-CT. The 12-point core biopsy of a tumor bed was performed in the operating room setting by previously marked tumor projections. Then, all patients underwent either breast-conserving surgery or mastectomy with immediate reconstruction with expander/implant. Results: After neoadjuvant therapy, in a group of 15 patients with TNBC in surgically obtained material, the pathologic complete response (pCR) was observed in 8 patients (53.33%), whereas residual disease was found in 7 (46.67%) patients. The core biopsy results showed no tumor cells in 10 (66.67%) patients, and were detected in 5 (33.33%) patients (p = 0.0011), the accuracy of the method in this group was 80%. The overall response rate in the group of 15 patients with HER2-positive breast cancer was 8 (53.33%) patients with residual disease and 7 (46.67%) patients with pCR. According to core biopsy, tumor cells were present in 3 (20%) patients and were absent in 12 (80%) patients (p = 0.0787). Conclusions: Avoiding surgical treatment through not less than 12-point core biopsy of a tumor bed in patients with complete regression after neoadjuvant therapy is a new trend in the treatment of breast cancer. Any new approach in this sphere requires a long-term elaboration, compliance with the safety principles, rethinking standard procedures and following-up patients.