[Complete response obtained by preoperative chemotherapy in a case of T4 rectal cancer]

A 48-year-old man, who had presented with anal pain and cloudy urine, was referred to our hospital. Colonoscopy showed a type 2 circular tumor at the higher rectum, and a diagnosis of well-differentiated adenocarcinoma was made by biopsy. CT demonstrated increased thickness of the rectum wall, an equivocal boundary between the rectum and the bladder, and abnormal gas production in the bladder. Following diagnosis of T4 rectal cancer, preoperative chemotherapy was initiated with the aim of downstaging the tumor and avoiding total pelvic exenteration. After 5 courses of mFOLFOX+bevacizumab, the tumor showed a partial response on CT, which enabled the tumor to be resected without sacrificing the bladder. The whole tumor was resected by performing low anterior resection (D3) and partial resection of the bladder. Subsequent pathological examination of the resected specimen indicated complete response to chemotherapy due to the absence of malignant cells. Because higher response rate is reported for modern chemotherapy, including targeted therapy, preoperative intensive chemotherapy is an option for the local treatment of advanced rectal cancer. Downstaging chemotherapy is expected to enhance the role of function-preserving surgery for T4 rectal cancer.