PATTERNS OF RESIDUAL DISEASE AFTER PREOPERATIVE CHEMORADIATION IN ULTRASOUND T3-RECTAL CARCINOMA

Background: Rectal carcinoma tends to recur locally, with invasion of adjacent organs and significant pelvic pain. Both radiation therapy al one and combined chemoradiation have been used in an attempt to decrea se the local recurrence rate and thereby improve survival. Although pr eoperative chemoradiation can clinically downstage rectal tumors, the pathologic extent of the residual disease has not been studied. Method s: Thirty-seven patients with T3 rectal cancer diagnosed by transrecta l ultrasonography (uT3) received 45 Gy with continuous infusion 5-fluo rouracil (300 mg/m2/day). Proctoscopy with mucosal/submucosal biopsy w as performed in patients (16 of 37) posttreatment and before definitiv e surgery. Results: Microscopic evaluation of the 37 resected specimen s showed a 30% (11 patients) pathologic complete remission rate. The p attern of residual disease in the remaining 26 patients showed that ni ne (25%) had microscopic residual tumor without evidence of mucosal in volvement. Of the 14 patients with a negative proctoscopic evaluation and biopsy only, five (36%) had no residual tumor on final pathology. Conclusions: After chemoradiation, the pathologic presentation of rect al cancer may be altered, making endoscopic procedures and mucosal/sub mucosal biopsies unreliable in detection of residual disease. Despite the relatively good pathologic complete remission rate noted in this s tudy, all patients undergoing chemoradiation for uT3 rectal carcinomas need definitive surgical resection to confirm a complete clinical rem ission.