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Multicenter Evaluation of Rectal cancer ReImaging pOst Neoadjuvant (MERRION) Therapy

Hanly, Ann M. MD*; Ryan, Elizabeth M. MB, BCh, BAO; Rogers, Ailín C. MB, BCh, BAO*; McNamara, Deborah A. MD; Madoff, Robert D. MD; Winter, Desmond C. MD, FRCSI*

doi: 10.1097/SLA.0b013e31828f6c91
Original Articles

Objective: The aim of this study was to evaluate the utility of reimaging rectal cancer post-CRT (chemoradiotherapy) with magnetic resonance (MR) imaging of the pelvis for local staging and computed tomography of thorax, abdomen, and pelvis (CT TAP) to identify distant metastases.

Background: The success of neoadjuvant CRT for locally advanced rectal cancer has changed an already complex management algorithm. There is no consensus whether patients should be restaged before surgery.

Methods: Data from 5 institutions with prospectively maintained databases including patients who received neoadjuvant CRT for locally advanced rectal cancer were acquired. Only patients who had been staged pre- and post-CRT with MR imaging and CT TAP were included. MR findings were correlated with histopathological stage using weighted κ (kappa) statistics to test agreement, where a κ value of less than 0.5 was deemed unacceptable.

Results: A total of 285 patients fulfilled the criteria for the study; 84% had American Joint Committee for Cancer stage 3 disease pre-CRT, and the remainder had stage 2 disease. Fourteen patients did not proceed to surgery post-CRT—2 were observed as “complete responders,” and the remainder either had unresectable disease or were unfit for surgery. MR imaging could not predict T stage (κ = 0.212) or nodal involvement (κ = 0.336). Most pertinently, MR imaging was unable to detect a complete pathological response (κ = 0.021), nor could it discriminate T4 disease (κ = 0.445). CT TAP restaging altered management in 6.7% of patients, who had metastatic disease.

Conclusions: MR reimaging using standard protocols is of limited value in determining surgical approaches; a better modality of local restaging is required.

This multicenter study evaluated the utility of restaging 269 patients with rectal cancer post-CRT (chemoradiotherapy). Computed tomography of thorax, abdomen and pelvis post-CRT may identify patients with new metastases. Magnetic resonance reimaging using standard protocols is unable to locally stage rectal cancer post-CRT.

*Centre for Colorectal Disease, St Vincent's University Hospital, Elm Park, Dublin, Ireland

Beaumont Hospital, Dublin, Ireland

University of Minnesota Medical Center, Minnesota, Minneapolis, MN.

Address Correspondence and reprint request to: Desmond C. Winter, MD, FRCSI, Centre for Colorectal Disease, St Vincent's University Hospital, Dublin 4, Ireland; E-mail: deswinter@gmail.com.

A.M.H. and E.M.R. contributed equally to the study. The MERRION study group (members are listed under acknowledgments) contributed a lot to the study.

Disclosure: The authors declare no conflicts of interest.

© 2014 by Lippincott Williams & Wilkins.