Association of SLC7A5/LAT1 Expression with Clinicopathological Parameters and Molecular Subtypes: Could It Be Considered in the Management of Breast Cancer?

Introduction: Breast cancer is a heterogeneous malignancy influenced by diverse molecular profiles. The L-type amino acid transporter 1 (LAT1), encoded by the SLC7A5 gene, plays a key role in tumor metabolism, growth, and angiogenesis. Through its role in amino acid transport and activation of the mTORC1 signaling pathway, LAT1 has emerged as a potential therapeutic target. Objective: To evaluate SLC7A5/LAT1 expression and its association with clinicopathological parameters and molecular subtypes of invasive carcinoma of no special type (NST) in a Pakistani cohort. Methods: Eighty-three patients who underwent mastectomy or modified radical mastectomy for histologically confirmed primary invasive carcinoma of no special type were included. Immunohistochemistry was used to assess SLC7A5/LAT1 expression. Associations with clinicopathological features and molecular groups were analyzed using the Chi-square test. Results: The mean age of SLC7A5-positive patients were 48.4 ± 10.8 years. Overall, 24.1% of patients demonstrated SLC7A5 positivity. Although SLC7A5 expression was more frequent in cases categorized as having moderate or poor prognosis based on the Nottingham Prognostic Index (NPI), this trend was not statistically significant. Similarly, no significant associations were observed between SLC7A5 expression and other clinicopathological or molecular variables. Conclusions:SLC7A5/LAT1 expression was identified in approximately one-quarter of invasive breast carcinoma cases. Its expression appeared more common in tumors with poorer NPI categories, but without statistically verified associations. These findings suggest that SLC7A5 may act independently of conventional clinicopathological parameters. Larger, longitudinal studies with survival follow-up are required to clarify its prognostic and therapeutic significance.