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

Abstract 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.