MRI identified prognostic features of tumors in distal sigmoid, rectosigmoid, and upper rectum: treatment with radiotherapy and chemotherapy.

PURPOSE: Neoadjuvant therapy is traditionally reserved for locally advanced mid and low rectal cancers. In tumors above this level, the need for adjuvant treatment is based on poor histopathologic features, but this approach has potential disadvantages. The aim of this study was to determine whether magnetic resonance imaging (MRI) could accurately stage tumors of the distal sigmoid, rectosigmoid, and upper rectum and help direct preoperative treatment. MATERIALS AND METHODS: A total of 75 patients with distal sigmoid, rectosigmoid, and upper rectal tumors were assessed preoperatively by MRI. If tumor extended beyond the planned surgical resection plane, chemoradiotherapy was offered. RESULTS: Of the 75 patients, 57 (76%) underwent primary surgery. Agreement between the MRI prognosis and histopathologic findings was 84% (95% confidence interval [CI], 72.6-92.7%). The other 18 patients underwent neoadjuvant chemoradiotherapy for poor prognostic features with predicted surgical resection margin involvement. The histopathologic examination confirmed tumor downstaging in 9 of the 18 patients who underwent chemoradiotherapy. The 3-year survival rate in the good prognosis group (91%; 95% CI, 77.1-97.3%) was not significantly different from that of the chemoradiotherapy group (81.4%; 95% CI, 52.4-93.6%). The poor prognosis group undergoing primary surgery had significantly worse survival (62.2%; 95% CI, 30.3-82.8%, p < 0.03). CONCLUSION: Our findings indicate that tumors of the distal sigmoid, rectosigmoid, and upper rectum can be staged accurately using high spatial resolution MRI and that those with poor prognostic disease may benefit from preoperative therapy.