Survival Analysis for Adjuvant Chemotherapy vs Observation After Pathologic Complete Response and Resection in Rectal Cancer


Key Points

  • Adjuvant chemotherapy was associated with improved overall survival vs observation.
  • Overall survival rates at 1, 3, and 5 years were 99.7% vs 99.2%, 97.1% vs 93.6%, and 94.7% vs 88.4%.  

In a propensity-score matching analysis reported in JAMA Oncology, Polanco et al found that adjuvant chemotherapy was associated with a survival benefit vs observation among patients with locally advanced rectal cancer who underwent resection after pathologic complete response following neoadjuvant chemoradiotherapy.

Study Details

The study involved 741 patients who received adjuvant chemotherapy and 741 patients matched by propensity score who underwent observation from among 2,764 patients in the National Cancer Database between 2006 and 2012 who had stage II or III resected rectal adenocarcinoma and had received neoadjuvant chemoradiotherapy with pathologic complete response (ypT0N0M0).

Overall Survival

After median follow-up of 39 months, the adjuvant chemotherapy group had significantly improved overall survival vs the observation group (hazard ratio [HR] = 0.50, P = .005). Overall survival rates at 1, 3, and 5 years were 99.7% vs 99.2%, 97.1% vs 93.6%, and 94.7% vs 88.4%. In subgroup analysis, benefit of adjuvant chemotherapy was greatest among patients with clinical stage T3/T4 disease (HR = 0.48, 95% confidence interval [CI] = 0.30­–0.77) and those with clinical T3/T4 and node-positive disease (HR = 0.47, 95% CI =0.25–0.91); however, benefit was not significant across T/N stage subgroups (P = .77 for interaction).

The investigators concluded, “Adjuvant chemotherapy was associated with improved [overall survival] in patients with pathologic complete response after [neoadjuvant chemoradiotherapy] for resected locally advanced rectal cancer. This study supports the use of [adjuvant chemotherapy] in this setting where there is currently paucity of data.”

The study was supported in part by the Veterans Affairs North Texas New Investigator Program.

Patricio M. Polanco, MD, of the Division of Surgical Oncology, University of Texas Southwestern Medical Center, is the corresponding author for the JAMA Oncology article. 

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.