RECURRENCE OF HER2-POSITIVE BREAST CANCER IN PREMENOPAUSAL AND POSTMENOPAUSAL PATIENTS WHO HAVE ACHIEVED A PATHOLOGICALLY COMPLETE RESPONSE TO NEOADJUVANT SYSTEMIC THERAPY

Bekkeldieva Nestan Bekkeldievna, Semiglazov Vladimir Fedorovich, Krivorotko Petr Vladimirovich, Zernov Konstantin Yurevich

Introduction The current standard of treatment for patients with HER2-positive breast cancer who experience a pathomorphological complete response (pCR) after neoadjuvant therapy is to continue targeted adjuvant therapy with any degree of pathomorphological regression of the tumor. However, there is an ongoing debate about how different long-term outcomes are depending on RCB, i.e. the degree of pathomorphological response of the tumor. The aim of the study was to evaluate the effectiveness of dual targeted therapy in achieving a complete pathomorphological response in premenopausal and postmenopausal patients. Materials and methods. The study included 124 patients with breast cancer (with clinical stage II) who received treatment at the Department of breast Tumors of the Federal State Budgetary Institution "National Medical Research Center of Oncology named after N. N. Petrov" of the Ministry of Health of the Russian Federation from 2020 to 2022, who were divided into 2 groups depending on the age category. The first group included premenopausal patients, and the second group included postmenopausal patients. All patients received neoadjuvant systemic therapy with dual targeted therapy. After completion of neoadjuvant systemic therapy, surgical intervention of various volumes was performed, followed by a histological examination to assess the degree of pathomorphological regression of the tumor. Results: A complete pathomorphological tumor response (csc) was achieved in 58 (75.3%) premenopausal patients, and in 36 (76.6%) postmenopausal patients. Partial pathomorphological regression was achieved in 19 (24.7%) premenopausal and 11 (23.4%) postmenopausal patients with 3-year disease-free survival of 86.8% (95% CI 74.1 – 93.5) in premenopausal patients versus 90.5% (95% CI 73.2 – 96.9) in the postmenopausal group (p = 0.476). Conclusions The use of neoadjuvant chemotherapy and anti-HER2 double targeted blockade in patients with HER2-positive breast cancer allowed achieving a complete pathomorphological response in the majority of premenopausal and postmenopausal patients, 75.3% and 76.6%, respectively (p>0.005). The achievement of a complete pathomorphological tumor response (pCR) to HCT in both premenopausal and postmenopausal patients was "translated" into high rates of 3-year disease-free survival

Keywords:HER2-positive breast cancer, achievement of pCR; systemic targeted therapy, premenopausal and postmenopausal patients, disease-free survival.