MRI may predict prognosis of surgery in rectal cancer: JAMA
Magnetic resonance imaging (MRI) is an imaging modality that uses strong magnetic fields and radio waves to produce detailed images of the inside of the body.An MRI scanner is a large tube that contains powerful magnets. The patient is made to lie inside the tube during the scan.
The results of an MRI scan can be used to help diagnose conditions, plan treatments and assess how effective previous treatment has been.
The use of magnetic resonance imaging (MRI) criteria to select patients with good prognosis rectal cancer for primary surgery results in a low rate of positive circumferential resection margin (CRM), according to a recent study.
Results of the study, published in the journal JAMA Oncology suggests that chemoradiotherapy (CRT) may not be necessary for all patients with stage II and III rectal cancer.
Chemoradiotherapy (CRT), followed by surgery, is the recommended approach for stage II and III rectal cancer. While CRT decreases the risk of local recurrence, it does not improve survival and leads to poorer functional outcomes than surgery alone. Therefore, new approaches to better select patients for CRT are important. Erin D. Kennedy, Department of Surgery, University of Toronto, Toronto, Ontario, Canada, and colleagues conducted conduct a phase 2 study to evaluate the safety and feasibility of using MRI criteria to select patients with “good prognosis” rectal tumors for primary surgery.
The study included 82 patients newly diagnosed with rectal cancer with an MRI-predicted good prognosis between September 2014 and October 2016 at 12 high-volume colorectal surgery centers in Canada. MRI criteria for good-prognosis tumors consisted of: distance to the mesorectal fascia > 1 mm; definite T2, T2/early T3, or definite T3 with < 5 mm of the extramural depth of invasion; and absent or equivocal extramural venous invasion.
The primary outcome measure was a positive circumferential resection margin rate. Most patients were male (74%), and the median age at surgery was 66 years.
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Key findings of the study:
- Based on MRI, most tumors were midrectal (65% [n = 53]), T2/early T3 (60% [n = 49]), with no suspicious lymph nodes (63% [n = 52]).
- On final pathology, 91% (n = 75) of tumors were T2 or greater, 29% (n = 24) were node positive, and 59% (n = 48) were stage II or III.
- The positive CRM rate was 4 of 82 (4.9%; 95% CI, 0.2%-9.6%).
- Overall, 25 patients (30%) received adjuvant treatment, with 6 receiving chemoradiotherapy and 19 receiving chemotherapy. Among the 48 patients with stage II or III tumors, 42 (88%) did not receive any form of radiotherapy.
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"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," concluded the authors.