Neurotrophic Receptor Tyrosine Kinase 3 as a Prognostic Biomarker in Breast Cancer Using Bioinformatic Analysis

<i>Background and Objectives</i>: Neurotrophic receptor tyrosine kinase 3 (<i>NTRK3</i>) is a member of the tropomyosin receptor kinase family of receptor tyrosine kinases, which play a crucial role in neural development. However, owing to the limited number of studies about <i>NTRK3</i> and cancer, we aimed to investigate <i>NTRK3</i> as a potential prognostic marker for breast cancer (BC). <i>Materials and Methods</i>: We conducted a comprehensive analysis of <i>NTRK3</i> expression in BC using the Tumor Immune Estimation Resource, Gene Expression Profiling Interactive Analysis 2, and Kaplan-Meier Plotter databases. We also explored the association between <i>NTRK3</i> expression and tumor-infiltrating immune cells. <i>Results</i>: Low <i>NTRK3</i> expression showed poorer prognosis in BC, as well as with T stage, pathology, and the Luminal subtype. In BC (BRCA), <i>NTRK3</i> was positively correlated with CD4+ T cell, CD8+ T cell, macrophage, and neutrophil infiltration. <i>Conclusions</i>: These results suggest that <i>NTRK3</i> may serve as a prognostic biomarker and provide novel insights into tumor immunology in BC. Therefore, <i>NTRK3</i> represents a potential diagnostic and therapeutic target for BC treatment.