Using magnetic resonance imaging (MRI) to assess response to neoadjuvant chemotherapy or radiation may predict survival among persons with advanced rectal cancer.

In a prospective cohort study of 111 persons with locally advanced rectal cancer, researchers used MRI to measure tumor regression grade (assessing how much a tumor shrank) after patients underwent preoperative radiotherapy or chemoradiation. They also evaluated circumferential resection margin (CRM)—indicating the remaining cancer at the tumor edges after treatment, or predicted to remain after surgery. The study participants were deemed to be either “good” or “poor” responders to therapy based on MRI.

Five-year survival for poor response as determined by MRI assessments of tumor regression grade was 27%, compared with 72% for good responders. Disease-free survival was 64% for good responders vs 31% for poor responders. In addition, local recurrence rates at 5 years was 28% for those patients for whom there was MRI-predicted CRM involvement, compared with 12% for patients with predicted cancer-free tumor margins.

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In their report for Journal of Clinical Oncology, investigators Gina Brown, MBBS, MD, of the radiology department at the Royal Marsden Hospital NHS Trust in Sutton, United Kingdom, and colleagues concluded that MRI assessment of tumor regression grade and CRM are imaging markers that can predict survival outcomes for good and poor responders, and that these markers provide an opportunity for the care team to offer additional treatment options before planning definitive surgery.