Can Neoadjuvant Systemic Therapy Provide Additional Benefits for T1 HER2+ Breast Cancer Patients: a Subgroup Analysis Based on Different High-Risk Signatures.

Neoadjuvant systemic therapy (NAST) is vital in the management of HER2-positive (HER2+) breast cancer. Nevertheless, the indications for NAST in tumors <2 cm remain controversial. A total of 7961 patients were screened from the Surveillance, Epidemiology, and End Result database. Independent prognostic factors were identified using multivariate Cox analysis. Subgroup analyses and Kaplan–Meier analyses were used to simulate whether NAST would provide a survival benefit with different high-risk characteristics. Nomograms were constructed, and an internal validation cohort was employed. Of the 7961 included patients, 1137 (14.3