Background: Neoadjuvant chemotherapy (NAC) alone for locally advanced rectal cancer (LARC) remains an experimental treatment, and the efficacy in terms of long-term outcome has not been fully elucidated. The N-SOG 03 trial examined the safety and efficacy of neoadjuvant CAPOX and bevacizumab (Bev) without radiotherapy in patients with poor-risk LARC.
Methods: Thirty-two patients with MRI-defined LARC received neoadjuvant CAPOX and Bev followed by curative resection between 2010 and 2011. The overall survival (OS), progression-free survival (PFS), and local-relapse rate (LRR) were calculated using the Kaplan-Meier method, and the risk factors were evaluated by multivariate analysis using the Cox proportional hazard models. This trial is registered with UMIN, number 000003507.
Results: In the entire cohort, the 5-year OS was 81.3%. Because of disease progression during chemotherapy, 3 patients ultimately did not undergo curative surgery. As a result, 29 patients underwent R0/1 resection. Among these 29 patients, the 5-year OS, PFS, and LRR were 89.7%, 72.4% and 13.9%, respectively. In multivariate analysis, cT4b tumor was an independent poor prognostic factor for OS and LRR, and ypT4b tumor and absence of N down-staging were independent poor prognostic factors for PFS.
Conclusions: Patients with cT4b tumor were not suitable for NAC alone. However, the long-term outcomes of the other patients were satisfactory, and NAC alone might be an option for treatment of LARC. N down-staging was likely to bring favorable PFS, even in patients with cStage III.
Keywords: Neoadjuvant chemotherapy; Outcome; Phase II trial; Rectal cancer.