Polanco PM, et al. - Researchers compared the overall survival (OS) between adjuvant chemotherapy (AC) and postoperative observation (OB) in patients with rectal cancer with pathologic complete response following neoadjuvant chemoradiotherapy (nCRT) and resection. They noted an association of adjuvant chemotherapy with improved OS in these patients. In this setting where there is currently paucity of data, this study supports the use of AC.

Methods

• In the National Cancer Database, experts identified a cohort of patients with rectal cancer and a complete pathological response (ypT0N0) after nCRT between 2006 and 2012.
• They compared the patients who received AC with OB patients by propensity score matching.
• Using the stratified log-rank test and stratified Cox regression model, they compared overall survival.
• They also assessed the outcomes after AC vs OB in patient subgroups.
• In June 2017, the data analysis was completed.
• Overall survival was the main outcomes.

Results

• There were 2,764 patients (mean [SD] age, 60.0 [12.3] years; 40% female) were identified with clinical stage II or III resected adenocarcinoma of the rectum who had received nCRT and were complete responders (ypT0N0M0).
• Of these patients, 741 in the AC group were matched by propensity score to 741 patients who underwent OB.
• Compared with the OB cohort, the AC cohort had better OS (hazard ratio, 0.50; 95% CI, 0.32-0.79).
• Findings suggested that for the AC group, the 1-, 3-, and 5-year OS rates were 99.7%, 97.1%, and 94.7% and for the OB group these rates were 99.2%, 93.6%, and 88.4% (P=.005).
• Researchers noted in subgroup analysis that patients with clinical stage T3/T4 and node-positive disease benefited most from AC (hazard ratio, 0.47; 95% CI, 0.25-0.91).