Mandard Tumour Regression Grade, Perineural Invasion, Circumferential Resection Margin and Post-chemoradiation Nodal Status Strongly Predict Outcome in Locally Advanced Rectal Cancer Treated with Preoperative Chemoradiotherapy

Abstract

AimsThe pathology of tumours after chemo/radiotherapy for locally advanced rectal cancer can be difficult to interpret. The ypTNM staging does not accurately predict outcomes. Therefore, we developed a new prognostic index for this purpose. Materials and methodsThe Nottingham Rectal Cancer Prognostic Index (NRPI) is based on a study of 158 patients with locally advanced rectal cancer treated with preoperative chemo/radiotherapy at Nottingham University Hospital between April 2001 and December 2008. Patients were treated with radiotherapy to a dose of 50 Gy in 25 fractions over 5 weeks with/without concurrent capecitabine chemotherapy. Surgery was carried out after an interval of 6–10 weeks. Factors found to be significant on univariate analysis to predict for disease-free (DFS) and overall survival were further explored in multivariate analysis. The significant factors (Mandard tumour regression grade, perineural invasion, circumferential resection margin status and nodal status) were weighted to establish a score for the index. The median follow-up was 40 months (range 3–90 months). ResultsOn survival analysis, four distinct prognostic groups were found: Score 0 = excellent prognosis, 1–3 = good prognosis, 4–8 = moderate prognosis, 9–14 = poor prognosis. The NRPI significantly predicted both DFS and overall survival (P < 0.0001). DFS at 5 years was 95, 63, 25 and 0% for the four groups. On multivariate analysis the NRPI was found to be the strongest predictor of DFS including nodal and circumferential resection margin status (P < 0.0001). It was a stronger predictor of overall survival than the American Joint Committee on Cancer/Dukes staging (P < 0.0001). ConclusionsThe NRPI allocates patients into distinct prognostic categories. This seems to be a much stronger predictive factor than the American Joint Committee on Cancer/Dukes staging. This requires further validation, but seems to be a useful clinical index for future studies.