[Slc7a5 protein expression in breast cancer samples, relationship with clinical and morphological parameters of the tumor and its regional metastasis].

[OBJECTIVE] To define the role of SLC7A5 expression in establishing an aggressive phenotype in primary breast cancer, specifically its correlation with major clinicopathological characteristics and the capacity for early lymphatic spread.

[MATERIAL AND METHODS] The study included tumor samples from 358 breast cancer patients. SLC7A5 expression was assessed by immunohistochemistry and correlated with tumor parameters (size, histological type, grade (G), molecular subtype, ER, PR, HER2 status, Ki-67 index) and axillary lymph node status. Analysis was performed using the ² test, Kruskal-Wallis test, and univariate logistic regression.

[RESULTS] SLC7A5 expression was detected in 55.6% of cases (intense staining in 26.5%) and was associated with aggressive features: pT2-3 (=0.033), G3 (=0.001), Ki-67≥30% (<0.001), ER-negative (=0.022), and PR-negative status (=0.013). A subtype-specific pattern was observed: maximal frequency in HER2-positive non-luminal tumors (80%), minimal in luminal A (42.8%; <0.001). Expression in ≥10% of cells was more frequent in the lymph node metastasis group (51.8% vs. 31.8% in pN0; <0.001), and metastatic risk increased with expression intensity (<0.001). In age groups 18-44 and 60-74 years, as well as in ER-positive and G1 tumors, SLC7A5 positivity increased the odds of lymph node involvement by 2.26-6.5 times.

[CONCLUSION] SLC7A5 expression serves as an integral marker of breast cancer aggressiveness, associated with unfavorable immunophenotypes and independently predictive of lymphogenous metastasis. Its assessment may improve risk stratification and help identify candidates for LAT1 inhibitor-targeted therapy.