Rectourethral fistula is rare complication after 125I low-dose-rate prostate brachytherapy, and gastrointestinal fistulas are widely recognized as a complication of bevacizumab. To our knowledge, this is the first case of rectourethral fistula during bevacizumab administration for cecum cancer after prostate brachytherapy. A 75-year-old man visited our hospital because of urinary retention and fecaluria. He had been receiving chemotherapy for one year against recurrence of cecum cancer. The chemotherapy regimens were bevacizumab and capecitabine plus oxaliplatin. He had undergone laparoscopic ileocecal resection for cecum cancer 1.5 years earlier. Eight months after the operation, recurrence was recognized. He had a history of prostate cancer and had received 125I low-dose-rate prostate brachytherapy for prostate cancer 17 years earlier. Computed tomography revealed air bubble from the rectum to the prostate and urethra. To prevent urinary tract infection, laparoscopic transverse colostomy and percutaneous cystostomy were performed. Although the patient\u27s quality of life subsequently improved, the performance status declined remarkably. He was therefore transferred to another hospital and received the best supportive care. Rectourethral fistula is a rare but serious complication after 125I low-dose-rate prostate brachytherapy. The introduction of bevacizumab to patients who have received this therapy should be carefully considered
