Abstract
Introduction: We conducted a non-inferiority analysis using real-world data to compare the survival outcomes of stage T1-2N2-3 (tumor size ≤5 cm and four or more node metastases) breast cancer after breast-conserving surgery (BCS) and mastectomy (MAST).Methods: The study included patients with stage T1-2N2-3 invasive breast carcinoma from the Surveillance, Epidemiology, and End Results program, who underwent BCS or MAST between 2004 and 2012, along with both radiotherapy and chemotherapy. The statistical analyses used included the chi-squared test, multivariate Cox proportional hazards models, and propensity score matching (PSM).Results: The study population comprised 13,263 patients, including 4,787 (36.1%) and 8,476 (63.9%) patients who were treated with BCS and MAST, respectively. Patients with younger age and advanced stage were more likely to have received MAST. The probability of receiving MAST increased over the years, while the probability of BCS decreased (p < 0.001). The 5-year breast cancer-specific survival (BCSS) was 86.1% in the BCS cohort compared to 83.1% in the MAST cohort (p < 0.001). Surgical procedure was an independent prognostic factor for BCSS. Patients who received MAST had worse BCSS than those treated with BCS (hazard ratio = 1.179, 95% confidence interval = 1.087–1.278, p < 0.001). These results remained significant after stratification by age, tumor grade, T stage, N stage as well as marital status. Similar results were obtained after PSM.Conclusions: BCS resulted in noninferior outcome than MAST in patients with T1-2/N2-3 invasive breast carcinoma. BCS may therefore be an optimal treatment option when both treatment options are feasible and appropriate.
Highlights
We conducted a non-inferiority analysis using real-world data to compare the survival outcomes of stage T1-2N2-3 breast cancer after breast-conserving surgery (BCS) and mastectomy (MAST)
Several retrospective studies have shown that BCS has superior outcomes to MAST in N2-3 breast cancer, the adjuvant treatment provided, including chemotherapy and RT, was found to be insufficient in most cases, which might have affected the evaluation of the results [2, 14, 17, 18]
Patients with pathologically diagnosed T1-2N23M0 invasive breast cancer treated with BCS+postoperative beam RT+chemotherapy or MAST+postoperative beam RT+chemotherapy between 2004 and 2012 were included from the population-based Surveillance, Epidemiology, and End Results (SEER) program [19]
Summary
We conducted a non-inferiority analysis using real-world data to compare the survival outcomes of stage T1-2N2-3 (tumor size ≤5 cm and four or more node metastases) breast cancer after breast-conserving surgery (BCS) and mastectomy (MAST). The usefulness of BCS in patients with N2-3 breast cancer remains unclear, especially for those in the N3 class, which is often considered as a contraindication for BCS [16] This is probably because in patients with N2-3 disease, the risk of local recurrence and distant metastasis is significantly higher than that in patients with N0 and N1 disease [6]. Several retrospective studies have shown that BCS has superior outcomes to MAST in N2-3 breast cancer, the adjuvant treatment provided, including chemotherapy and RT, was found to be insufficient in most cases, which might have affected the evaluation of the results [2, 14, 17, 18]. There is clearly a need to analyze these findings in a population of N23 breast cancer patients who underwent BCS and received appropriate adjuvant treatment
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