The neoadjuvant rectal score and a novel magnetic resonance imaging based neoadjuvant rectal score are stage independent predictors of long-term outcome in locally advanced rectal cancer

McMahon, R. K., O'Cathail, S. M. , Nair, H., Steele, C. W. , Platt, J. J., Digby, M., McDonald, A. C., Horgan, P. G. and Roxburgh, C. S.D. (2023) The neoadjuvant rectal score and a novel magnetic resonance imaging based neoadjuvant rectal score are stage independent predictors of long-term outcome in locally advanced rectal cancer. Colorectal Disease, 25(9), pp. 1783-1794. (doi: 10.1111/codi.16667) (PMID:37485654)

Abstract

Aim: Neoadjuvant rectal (NAR) score is an early surrogate for longer-term outcomes in rectal cancer undergoing radiotherapy and resection. In an era of increasing organ preservation, resection specimens are not always available to calculate the NAR score. Post-treatment magnetic resonance imaging (MRI) re-staging of regression is subjective, limiting reproducibility. We explored the potential for a novel MRI-based NAR score (mrNAR) adapted from the NAR formula. Methods: Locally advanced rectal cancer patients undergoing neoadjuvant therapy (nCRT) and surgery were retrospectively identified between 2008 and 2020 in a single cancer network. mrNAR was calculated by adapting the NAR formula, replacing pathological (p) stages with post-nCRT MR stages (ymr). Cox regression assessed relationships between clinicopathological characteristics, NAR and mrNAR with overall survival (OS) and recurrence-free survival (RFS). Results: In total, 381 NAR and 177 mrNAR scores were calculated. On univariate analysis NAR related to OS (hazard ratio [HR] 2.05, 95% confidence interval [CI] 1.33–3.14, p = 0.001) and RFS (HR 2.52, 95% CI 1.77–3.59, p = 0.001). NAR 3-year OS <8 was 95.3%, 8–16 was 88.6% and >16 was 80%. mrNAR related to OS (HR 2.96, 95% CI 1.38–6.34, p = 0.005) and RFS (HR 2.99, 95% CI 1.49–6.00, p = 0.002). 3-year OS for mrNAR <8 was 96.2%, 8–16 was 92.4% and >16 was 78%. On multivariate analysis, mrNAR was a stage-independent predictor of OS and RFS. mrNAR corresponded to NAR score category in only 15% (positive predictive value 0.23) and 47.5% (positive predictive value 0.48) of cases for categories <8 and >16, respectively. Conclusions: Neoadjuvant rectal score is validated as a surrogate end-point for long-term outcomes. mrNAR categories do not correlate with NAR but have stage-independent prognostic value. mrNAR may represent a novel surrogate end-point for future neoadjuvant treatments that focus on organ preservation.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Horgan, Professor Paul and McMahon, Mr Ross and Nair, Harikrishnan and Steele, Dr Colin and O'Cathail, Dr Sean and Roxburgh, Professor Campbell
• Authors: McMahon, R. K., O'Cathail, S. M., Nair, H., Steele, C. W., Platt, J. J., Digby, M., McDonald, A. C., Horgan, P. G., and Roxburgh, C. S.D.
• College/School: College of Medical Veterinary and Life Sciences > School of Cancer Sciences; College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing
• Journal Name: Colorectal Disease
• Publisher: Wiley
• ISSN: 1462-8910
• ISSN (Online): 1463-1318
• Published Online: 23 July 2023
• Copyright Holders: Copyright © 2023 The Authors
• First Published: First published in Colorectal Disease 25(9): 1783-1794
• Publisher Policy: Reproduced under a Creative Commons License