A single-institution phase II trial of five fractions of radiotherapy followed by four courses of FOLFOX chemotherapy as preoperative therapy for rectal adenocarcinoma.

553 Background: Preoperative radiotherapy (RT) with 5FU chemotherapy (CT) is a standard of care for cT3-4 rectal cancer. Studies incorporating additional cytotoxic agents have resulted in increased morbidity with little benefit. We evaluate a template that seeks to (1) include the known benefits of preoperative RT on local response/control, (2) provide for preoperative multi-drug CT, (3) avoid the morbidity of concurrent RT and multi-drug CT. Methods: Patients with cT3-4, any N, any M rectal cancer were eligible. Patients were confirmed to be candidates for surgery, provided the response was sufficient. Preoperative treatment was 5 fractions RT (25 Gy to involved mesorectum, 20 Gy to elective nodes), followed by 4 cycles of mFOLFOX6. Postoperative CT was at the discretion of the medical oncologist. The principal objectives are to demonstrate that this regimen can achieve T stage down staging (ypT < cT) and acute grade 3+ gastrointestinal (GI) morbidity equal to or better than historical controls. Results:...