Should the Breast Cancer Staging System be Revised?

Objective The purpose of this study was to determine whether breast cancer patients at stage T2N0 with tumor size >= 4 cm and <4 cm.Method Patients with T2N0 stage breast cancer diagnosed between 2010 and 2019 were analyzed in 2 groups as <4 cm (T2a) and >= 4 cm (T2b) in the study using the SEER 17 Research Plus database. The patients' clinicopathological characteristics and oncological outcomes were included. Group comparisons of prognostic factors, overall survival (OS), and cancer-specific survival (CSS) were made.Results In this study, which involved 70971 patients, the T2a group had higher 5-year OS rate (87.2 +/- .2 vs 80.8 +/- .5%) and 5-year CSS rate (93.7 +/- .1% vs 89.4 +/- .4%) than the T2b group (P < .001). Univariate analysis revealed that the overall risk of death was 1.5 times higher in T2b than T2a (HR: 1.533 [95% CI: 1.450-1.622], P < .001), whereas multivariate analysis demonstrated the risk was 1.4 times higher (HR: 1.384 [95% CI: 1.307-1.466], P < .001). The risk of cancer-specific death was 1.7 times higher in univariate analysis (HR: 1.691 [95% CI: 1.561-1.832], P < .001) and 1.4 times higher in multivariate analysis (HR: 1.420 [95% CI: 1.309-1.541], P < .001).Conclusion Overall survival and BCSS rates in stage T2b breast cancer patients are significantly lower than in T2a patients. Tumor size >= 4 cm in breast cancer is a negative predictor of prognosis.