Breast cancer is a leading cause of cancer morbidity and mortality among young women, who often experience more aggressive disease, which may impact their treatment responses and long-term prognoses. Understanding the effectiveness of neoadjuvant chemotherapy (NAC) versus adjuvant chemotherapy (AC) in this specific population is critical for optimizing treatment strategies and improving prognoses. This research was conducted to compare the prognoses of young women (≤35 years old) with early-stage hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer, who were treated with NAC versus those treated with AC. This study retrospectively analyzed data from young women with HR+/HER2- breast cancer, with complete follow-up information, sourced from the Surveillance, Epidemiology, and End Results (SEER) database (2010-2018) and the Tianjin Medical University Cancer Institute and Hospital (TJMUCH) (2014-2018). Patients from both cohorts were allocated to NAC and AC groups based on their treatment regimens. Categorical variables were compared using chi-square, whereas the Kaplan-Meier method was utilized to generate survival curves
additionally, the log-rank test was employed for survival analysis. Propensity score matching (PSM) was employed to control baseline differences. Analysis of the SEER and TJMUCH cohorts revealed that patients treated with NAC had significantly worse overall survival (OS) compared to those treated with AC, as indicated by Kaplan-Meier curves both before and after PSM. The disease-free survival analysis of the TJMUCH cohort yielded similar results, indicating that patients treated with AC experienced longer periods without disease recurrence compared to their counterparts receiving NAC. Statistically significant differences were observed across both survival metrics, reinforcing the robustness of our findings. Overall, among young women (≤35 years old) with early-stage HR+/HER2- breast cancer, patients treated with AC exhibited a more favorable prognosis and improved survival outcomes compared to those treated with NAC. These findings could potentially influence clinical decision-making and treatment guidelines, advocating for a more tailored approach in managing young women with HR+/HER2- breast cancer.