Clinical treatment score Post-5 Years (CTS5) predicts the benefit of postmastectomy radiotherapy in patients with T1-2N1 luminal breast cancer.

PURPOSE

To investigate the clinical value of Clinical Treatment Score Post-5 Years (CTS5) to predict the survival benefits of postmastectomy radiotherapy (PMRT) of patients with T1-2N1 luminal breast cancer (BC).

METHODS

Patients who were diagnosed with T1-2N1 luminal BC between 2010 and 2015 were included in the Surveillance, Epidemiology, and End Results database. The chi-square test, binomial logistic regression, Kaplan-Meier analysis, and multivariable Cox proportional hazard model were used for statistical analyses.

RESULTS

A total of 11190 patients were included with a median follow-up time of 76 months. Regarding the CTS5 classification, 1641 (14.7 %), 3915 (35.0 %), and 5633 (50.3 %) patients had low-risk, intermediate-risk, and high-risk diseases, respectively. Patients with younger age, T2 stage, higher tumor grade, a higher number of positive lymph nodes, infiltrating lobular carcinoma subtype, and receipt of chemotherapy were associated with the receipt of PMRT (all P < 0.05). The multivariate analysis showed that the receipt of PMRT was the independent prognostic factor associated with better BCSS (P = 0.005) and OS (P < 0.001). The sensitivity analysis showed that PMRT did not improve BCSS (low-risk, P = 0.932; intermediate-risk, P = 0.952) and OS (low-risk, P = 0.637; intermediate-risk, P = 0.825) compared to those without PMRT in the low-risk and intermediate-risk groups. However, PMRT improved BCSS (P = 0.003) and OS (P < 0.001) in those with high-risk groups compared to those without PMRT.

CONCLUSIONS

CTS5 is an innovative model that could predict the survival benefit of PMRT for T1-2N1 luminal BC patients.