Low expression of TOX predicts poor prognosis of patients with breast cancer in the real world: A retrospective study.

Background: TOX is a transcription factor that is implicated in the regulation of T cell exhaustion in tumors. TOX has been proven to have prognostic value in some malignant tumors. We aim to analyze the expression of TOX in breast cancer patients, and the association between TOX and prognostic significance in patients with breast cancer.

Methods: 313 breast cancer patients were enrolled into this study. The expression of TOX was determined by immunohistochemistry assay. Survival curves were performed by Kaplan-Meier and log-rank test. The potential independent factors were assessed by Cox regression analyses. Nomogram models, calibration curve, decision curve analyses were applied to analyze the clinical utility of predictive models.

Results: According to semi-quantitative scoring, 129 patients were classified into low group, and 184 patients were classified into high group. Patients with high expression of TOX had a longer survival than those with low expression of TOX (DFS: 71.70 vs. 64.05 months, χ = 11.6300, P = 0.00065; OS: 81.03 vs. 73.72 months, χ = 11.4200, P = 0.00073). Based on Cox regression analyses, multivariate analysis indicated that TOX was the potential prognostic factor for both DFS (HR: 0.412, 95 % CI: 0.248-0.684, P = 0.001) and OS (HR: 0.395, 95 % CI: 0.237-0.660, P < 0.0001). Calibration curve analysis showed that the predicted line was well-matched with baseline regarding postoperative 1-, 3-, and 5-year survival rate.

Conclusions: The expression of TOX is a potential prognostic factor, and can be a promising biomarker for predicting survival in breast cancer patients.