THE INFLUENCE OF CLINICAL AND MORPHOLOGICAL FACTORS ON THE EXPRESSION OF DRUG PATHOMORPHOSIS IN PATIENTS WITH BREAST CANCER AFTER NEOADJUVANT POLYCHEMOTHERAPY
Relevance. The effectiveness of NACT varies depending on the immunohistochemical (IHC) type of breast cancer. Over the past decade, according to the data of world and domestic literature, there has been a trend towards an increase in the frequency of achieving pCR, mainly in highly aggressive IHC types, which dictates the need to change the existing provisions on locoregional treatment of breast cancer. Purpose of the study. Determination of clinical and morphological predictors influencing the severity of therapeutic pathomorphosis in patients with breast cancer after NACT. Materials and methods. The study included 200 patients with breast cancer who underwent surgical treatment after NACT in 2013-2020. The mean age was 51.9±10.6 years. Stage I breast cancer was found in 5 patients (2.5%), stage II 113 (56.5%), III 82 (41%) (IIIB stage was excluded). Invasive cancer of a nonspeci c type was diagnosed in 90.5% of cases, invasive lobular cancer in 5.0%, combined cancer 1.5%, mucinous cancer 3.5%. Luminal type A was detected in 9.5% of cases, luminal type B, Her2/neu negative in 32%, luminal type B, Her2/neu positive 17%, Her2/neupositive type 13%, triple negative type 28.5%. The most common NAPCT regimen was 4AC+4T for luminal and triple negative types of breast cancer (39.5%), for her2/neu-positive types 4AC+4TN (14%). Results and conclusion. Clinical and morphological factors signi cantly affecting the severity of drug-induced pathomorphosis in breast cancer patients after neoadjuvant polychemotherapy are the immunohistochemical type of breast cancer, which is achieved with prognostically unfavorable types of breast cancer (Her2/neu-positive, luminal B/her2positive and triple negative types) (p<0.001), as well as in poorly differentiated forms of breast cancer. The severity of therapeutic pathomorphosis is also influenced by the number of metastatically altered regional lymph nodes, with an increase in the number of which the probability of achieving pCR is reduced by 30% and the level of the proliferative index Ki67, with each unit of Ki67 the probability of achieving pCR is higher (p<0.05).