Survival outcomes of neoadjuvant versus adjuvant therapy in patients with T1c, node-negative, human epidermal growth factor receptor 2-positive breast cancer: A Surveillance, Epidemiology, and End Results population-based study

Background: Persistent debates exist regarding the superiority of neoadjuvant therapy (NAT) over adjuvant therapy (AT) for patients with T1c, node-negative, human epidermal growth factor receptor 2-positive (HER2+) +) breast cancer, and relevant guidelines for these patients are lacking. Methods: Data on patients with T1cN0M0-stage HER2+ + breast cancer who received chemotherapy and surgery were extracted from 2010 to 2020 from the Surveillance, Epidemiology, and End Results database. Propensity score matching (PSM) was used to create well-balanced cohorts for the NAT and AT groups. Kaplan-Meier (KM) analysis and Cox proportional hazards models were used to assess the differences between NAT and AT in terms of overall survival (OS) and breast cancer-specific survival (BCSS). Additionally, logistic regression models were used to explore factors associated with response to NAT. Results: After PSM, 2140 patient pairs were successfully matched, which achieved a balanced distribution between the NAT and AT groups. KM curves revealed similar OS and BCSS between patients receiving NAT and those undergoing AT. A multivariate Cox model identified achieving pathological complete response (pCR) after NAT, compared with AT, as a protective prognostic factor for OS (hazard ratio, 0.52; 95% CI, 0.35-0.77; p < .001) and BCSS (hazard ratio, 0.60; 95% CI, 0.37-0.98; p = .041). A logistic regression model revealed that White race and hormone receptor-negative status independently predicted pCR. Conclusions: For patients with T1cN0M0-stage HER2+ + breast cancer, NAT demonstrated comparable OS and BCSS to AT. Patients who achieved pCR after NAT exhibited significantly better survival outcomes compared with those who received AT.