L-type
amino acid transporter 1 (LAT1), also referred to as
SLC7A5, is believed to regulate
tumor metabolism and be associated with
tumor proliferation. In invasive
breast cancer, we clinicopathologically investigated the utility of LAT1 expression. LAT1 expression was evaluated via immunohistochemistry analyses in 250
breast cancer patients undergoing long-term follow-up. We assessed the relationships between LAT1 expression and patient outcomes and clinicopathological factors.
Breast cancer-specific survival stratified by LAT1 expression was assessed.
Human epidermal growth factor receptor 2 (HER2)-positive patients with
metastasis received
trastuzumab therapy. The density of tumor-infiltrating lymphocytes (TILs) was evaluated according to the International Working Group guidelines. In the current study, high LAT1 expression was significantly correlated with
estrogen receptor (ER) negativity,
progesterone receptor negativity, high histological grade, increased TILs, and
programmed death ligand 1 positivity. Among the ER-positive and HER2-negative patients, high LAT1 was an independent
indicator of poor outcomes (hazard ratio (HR) = 2.97; 95% confidence interval (CI), 1.16-7.62; p = 0.023). Moreover, high LAT1 expression was an independent poor prognostic factor in
luminal B-like
breast cancer with aggressive features (HR = 3.39; 95% CI 1.35-8.52; p = 0.0094). In conclusion, high LAT1 expression could be used to identify a subgroup of invasive
breast cancer characterized by aggressive behavior and high
tumor immunoreaction. Our findings suggest that LAT1 might be a candidate therapeutic target for
breast cancer patients, particularly those with
luminal B-like type
breast cancer.