Association between FOXP3 Expression and Disease-Free Survival in Triple Negative Breast Cancer

Background & Objective: Triple-negative breast cancer (TNBC) is an aggressive subtype lacking estrogen, progesterone, and HER2 receptors, often leading to poor prognosis due to high recurrence and metastasis. FOXP3 expression, associated with suppressed anti-tumor immunity, is a potential prognostic marker in TNBC. However, the association between FOXP3 expression and disease-free survival (DFS) in TNBC remains controversial. This study aims to explore the relationship between FOXP3 expression and DFS in TNBC patients, contributing to the understanding of its prognostic significance. Methods: This retrospective study included 47 TNBC patients. Immunohistochemistry examination assessed FOXP3 expression, which was then categorized into low and high expression based on an optimal cut-off point. Univariate and multivariate analyses were conducted using Cox regression test to determine association between variables and DFS. Survival analysis was assessed using the Kaplan-Meier method and the log-rank test. Results: All patients were female mostly over 50 years old (66). The majority had tumors >2 cm (87.2) and LVI (66). High-grade tumors (grade 3) were predominant (93.6). Most patients showed moderate TIL levels (91.5). No significant associations were found between FOXP3 expression and age (p=0.253), tumor size (p=0.308), lymph node status (p=0.466), tumor grade (p=0.476), LVI (p=0.422), patient's stage (p=0.644), and TILs (p=0.783). However, high FOXP3 expression was significantly associated with worse DFS (p=0.019). Additionally, a higher stage was associated with worse DFS (p=0.002). Conclusion: High FOXP3 expression is associated with lower DFS in TNBC patients. FOXP3 expression was not associated with age, tumor size, lymph node status, tumor grade, LVI, TILs, or cancer stage. © 2025, Iranian Society of Pathology. All rights reserved.