The aim of this article was to study clinical and morphological features of luminal A subtype of breast cancer to assess its relationship with disease progression. Methods: This study included 79 patients with luminal A subtype of breast cancer who treatment in 2017 at the Lviv State Oncological Regional Treatment and Diagnostic Center. The Luminal A subtype was identified by immunohistochemistry (IHC) as ER+, PR+/-, HER2- and Ki-67 less than 20 percent on surgically resected breast cancer tissue. Results: The mean age of patients was 60,41±12,25 (range, 32–85 years), 26 (32,9%) were under 55 years. Nottingham Histologic Grade distribution was as follows: G1 – 10 (12,66%), G2 – 56 (70,88%), and G3 – 13 (16,46%) cases. Clinical stage II – 35 (44,3%) and III – 31 (39,24%) was observed. Menopausal status was in 67,1% of cases. Morphological analysis of the tumor tissue showed that except alveolar structures, there were trabecular, solid, tubular structures and separately located groups of tumor cells. The stromal component of the tumor was weak or moderate, most tumors showed minimal or marked inflammatory infiltration and low proliferative activity. Conclusions: To predict the probability of lymphogenic metastasis should be considered: menstrual function, histologic grade, the presence of alveolar structures in the infiltrative component, the different
types of structures in the infiltrative component, hyalinosis in the stroma of the tumor node and
inflammatory infiltration of tumor.