Relationships between pathological factors and long-term outcomes in patients enrolled in two prospective randomized controlled trials comparing the efficacy of oral tegafur–uracil with CMF (N·SAS-BC 01 trial and CUBC trial)

Purpose To evaluate the efficacies of cyclophosphamide, methotrexate, and fluorouracil (CMF) and tegafur–uracil (UFT) as adjuvant therapy in patients with resected stage I–IIIA breast cancer by immunohistochemistry (IHC)-based subtype and to determine the relationships between clinicopathological factors and long-term outcomes. Methods A pooled analysis of the randomized controlled N·SAS-BC 01 and CUBC studies was conducted. Expression of hormone receptors (HRs; estrogen and progesterone receptors), human epidermal growth factor receptor 2 (HER2), and Ki67were assessed by IHC. Tumor-infiltrating lymphocytes (TILs) and nuclear/histological grades were determined by hematoxylin and eosin staining. Relapse-free survival (RFS) and overall survival (OS) were estimated by Kaplan–Meier analysis and hazard ratios were determined by Cox model adjusted for baseline tumor size and nodal status. Results A total of 689 patients (342 CMF and 347 UFT) were included in the analyses with a median follow-up of 11.1 years. There was no significant difference in RFS or OS between the two cohorts (RFS: 0.96 [95% confidence interval: 0.71–1.30], log-rank test p = 0.80; OS: 0.93 [0.64–1.35], p = 0.70). There was no difference in RFS or OS between the two cohorts for HR+/HER2− and HR+/HER2+ subtypes. RFS was significantly longer in patients treated with UFT compared with CMF in patients with HR−/HER2+ subtype (0.30 [0.10–0.88], p = 0.03). A high TILs level was associated with a better OS compared with low TILs level (p = 0.02). Conclusions This long-term follow-up study showed that RFS and OS were similar in patients with luminal-type breast cancer treated with CMF and UFT.