Impact of neoadjuvant and adjuvant chemotherapy on breast cancer prognosis in a propensity score matched population

Breast cancer is the most common cancer among women worldwide. To evaluate the real-world effectiveness of Neo-adjuvant chemotherapy (NACT) and adjuvant chemotherapy (ACT), we conducted a retrospective study comparing their impact on breast cancer prognosis. We retrieved data from the SEER database. We applied propensity score matching (PSM) to minimize confounding factors. Breast-cancer specific survival (BCSS) and overall survival (OS) were compared between the two groups. We also developed a nomogram prognostic model using clinicopathological parameters to predict survival rates. We identified 46,447 eligible patients in the SEER database. After PSM, 9,025 patients were included in each group, with 11,762 patients receiving NACT and 34,685 undergoing ACT before PSM. In the PSM cohort, the 5-year BCSS and OS were 88.3% (95% CI: 87.6-89.0%) and 85.7% (95% CI: 84.9-86.5%) for the NACT group, respectively. Notably, patients in the ACT group showed significantly better survival prognosis compared to those in the NACT group. We also developed nomograms to predict the 3-year, 5-year, and 8-year OS and BCSS rates for patients receiving NACT or ACT. Breast cancer patients who undergo surgery followed by ACT have a more favorable prognosis compared to those receiving NACT before surgery.