Neoadjuvant chemoradiotherapy for rectal cancer: how important is tumour regression?

Pathological complete response following neoadjuvant chemoradiotherapy (CRT) for locally advanced rectal cancer is associated with reduced local recurrence and improved long-term outcome. However, the prognostic value of a partial response, or of tumour regression in patients with metastatic disease, is less clear.

We present a single-centre cohort study of 205 patients with stage II-IV rectal cancer treated with surgery and neoadjuvant CRT between 2006 and 2013. Tumour regression was assessed using the Dworak system.

The probability of 3-year recurrence-free survival (RFS) was 95% for Dworak grade 4, 82% for grade 3, 64% for grade 2 and 53% for grade 1 (P = 0.0005). In univariate regression analysis, Dworak grade was associated with RFS (hazard ratio (HR) 0.51, P < 0.0001; trend analysis) and cancer-specific survival (HR 0.52, P = 0.002). In multivariate analysis, Dworak grade remained an independent predictor of RFS (HR 0.62, P = 0.012), along with clinical metastases stage, resection margin status, the presence or absence of extramural venous invasion and type of surgical procedure.

Tumour regression grade after neoadjuvant CRT was an independent prognostic factor for RFS, highlighting the importance of the degree of local response to CRT.