[A Case of Pathologically Complete Response of a Rectal Cancer after Preoperative Treatment with mFOLFOX6 and Radiation Therapy].

A 60-year-old man who had bloody stools after sigmoid colonoscopy was admitted to our hospital. A digital examination and sigmoid colonoscopy showed a type 2 circular tumor at location Rb with incomplete mobility and tumor hemorrhage, and the result of a biopsy was moderately differentiated adenocarcinoma (tub2). Computed tomography and magnetic resonance imaging suggested a possibility of invasion of the primary rectal tumor to the sacrum. The clinical stage was cT4bN0M0H0P0, cStage Ⅱ, which is generally not treatable by surgery. Sigmoid colostomy was performed, and a central venous port was implanted. After a preoperative treatment consisting of 3 courses of mFOLFOX6 and radiation therapy, the clinical stage changed to ycT2N0M0H0P0, ycStageⅠ. Super-low anterior resection and covering ileostomy were performed 46 days after the preoperative treatment. A pathological examination revealed no residual cancer cells in the primary lesion and lymph node (Grade 3, pCR). The patient has been disease-free for 4 years and 9 months after the operation.