Complete response to preoperative chemoradiotherapy improves survival in rectal cancer

Patients with pathological complete response to preoperative chemoradiotherapy have longer relapse-free (RFS) and overall survival (OS) rates than those with residual disease, suggests a recent study.

The authors retrospectively reviewed medical records of patients with locally advanced rectal cancer, who were treated with preoperative chemoradiotherapy followed by surgery between 2002 and 2016.

They also classified tumour regression grade (TRG) into five categories based on the pathological response: TRG1 (no viable cancer cell), TRG2 (single cancer cell or small groups of cancer cells), TRG3 (residual tumour outgrown by fibrosis), TRG4 (residual tumour outgrowing fibrosis), TRG5 (diffuse residual tumour without regression). TRG1, TRG2+ TRG3, and TRG4+ TRG5 were grouped as complete response, intermediate response, and no response, respectively.

A total of 182 patients with locally advanced rectal cancer (mean age, 54.4 years; 61.5 percent male) were analysed. Of these, 24 (13.2 percent) had complete response, 105 (57.7 percent) intermediate response, and 53 (29.1 percent) no response. The corresponding 5-year RFS and OS rates were 79.8–92.3 percent, 74.7–79.4 percent, and 55.7–55.8 percent (RFS: p<0.05; OS: p<0.05).

According to ypTNM stage, no significant difference in RFS was seen among TRG groups in ypStage I and II patients (p>0.05). In ypStage III patients, RFS was 62 months in the no response group and was not reached in the intermediate response group (p<0.05). No significant difference was also observed in OS among TRG groups in ypStage I, II, and III patients (p>0.05).

Multivariate analysis revealed that pathological complete response was an independent variable for RFS (hazard ratio [HR], 0.34, 95 percent confidence interval [CI], 0.17–6.77) and OS (HR, 0.39, 95 percent CI, 0.18–0.83).