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. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s10549-020-06018-1) contains supplementary material, which is available to authorized users.