[A case of advanced rectal cancer that showed complete response to the addition of XELOX+bevacizumab therapy to preoperative chemoradiotherapy with S-1/CPT-11].

A 51-year-old man presented with a chief complaint of constipation. Rectal cancer was detected up to 13 cm proximal to the anal verge. The cancer was a fully circumferential type II tumor that was accompanied by prostate invasion and lymph node metastasis. After sigmoid colostomy, preoperative chemoradiotherapy with S-1/irinotecan (CPT-11; total 50 Gy) was administered, resulting in tumor volume reduction. However, because of residual invasion in some parts of the prostate, therapy with capecitabine and oxaliplatin (XELOX) plus bevacizumab was added to avoid pelvic exenteration. Because magnetic resonance imaging revealed no invasion prostate after 7 courses of the therapy, abdominoperineal resection of the rectum was performed. Pathological examination revealed no residual tumor cells, and a pathological complete response was thus confirmed. The addition of chemotherapy to preoperative chemoradiotherapy was considered to be an effective strategy for locally advanced rectal cancer in this case.