In a phase 2 clinical trial, magnetic resonance imaging (MRI) criteria-selected rectal cancer patients who skipped standard preoperative chemoradiotherapy (CRT) and underwent primary surgery had a low rate of circumferential resection margin (CRM) positivity. The prospective, multicenter, nonrandomized trial results were published online in JAMA Oncology and suggested that not all patients with stage II and stage III disease need CRT.1

The trial ( identifier: ISRCTN05107772) included 82 rectal cancer patients eligible for radical resection from 12 hospitals in Canada. All patients had a good prognosis rectal tumor according to MRI criteria and underwent primary surgery.

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The study participants were predominantly male (74%) and had a median age of 66 years (range, 37-89 years) at the time of primary surgery. The majority had tumors that were midrectal (65%), T2 or early T3 disease (60%), and no suspicious lymph nodes (63%).

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Final pathology showed that for the majority of patients, the quality of the total mesorectal excision was complete (82%) or near complete (16%), tumors were T2 or greater (91%), lymph nodes were negative (71%), and disease was stage II or stage III (59%). Negative CRM status was achieved for most patients (95%), resulting in a low CRM positivity rate of 4.9% (95% CI, 0.2%-9.6%).

“The use of MRI criteria to select patients with good prognosis rectal cancer for primary surgery results in a low rate of positive CRM and suggests that CRT may not be necessary for all patients with stage II and III rectal cancer,” the study authors wrote in conclusion.

The authors of a corresponding editorial wrote that the study was a “well-designed prospective multi-institutional study” but cautioned that the results “should not be extrapolated to patients with higher-risk disease.”2


  1. Kennedy ED, Simunovic M, Jhaveri K, et al. Safety and feasibility of using magnetic resonance imaging criteria to identify patients with “good prognosis” rectal cancer eligible for primary surgery: The phase 2 nonrandomized QuickSilver clinical trial [published online April 11, 2019]. JAMA Oncol. doi: 10.1001/jamaoncol.2019.0186
  2. Paty PB, Cercek A, and Crane CH. Reducing the morbidity of rectal cancer treatment [published online April 11, 2019]. JAMA Oncol. doi: 10.1001/jamaoncol.2019.0181