Development and validation of nomograms predicting survival in female patients with HER2-positive T1-3N0-1 breast cancer following breast-conserving surgery: a Surveillance, Epidemiology, and End Results database analysis

CONCLUSIONS: We present the first validated nomograms integrating tumor multiplicity, sociodemographic factors, and treatment response for HER2-positive BC. "Multiple primary tumors" emerged as a novel prognostic indicator, suggesting unexplored biological aggression. Our risk stratification translates to actionable strategies: chemotherapy de-escalation may be warranted in low-risk patients, as they derive no clear CSS benefit from NAC. Conversely, patients within the high-risk category are...