[A Case of Locally Advanced Rectal Cancer with Abscess and Rectovesical Fistula Curatively Resected Following Preoperative Chemotherapy].

A 63-year-old man with bloody stools, anal incompetence, and feeling of fatigue was diagnosed as having a RAS mutanttype rectal cancer with abscess and rectovesical fistula. Computed tomography revealed that the tumor had invaded the seminal vesicle, prostate, and bladder and formed an abscess. In addition, his general condition was poor. Thus, we evaluated the lesion as unresectable. His nutritional status improved, and the infection was controlled after colostomy. Then, we performed chemotherapy with 5-fluorouracil, Leucovorin, and oxaliplatin(FOLFOX)plus bevacizumab. However, after a single course of chemotherapy, the systemic inflammatory reaction was prolonged. Despite treatment of the infection with antibiotics, it was not fully controlled, making it difficult to continue chemotherapy. A new lesion did not appear, but the primary tumor increased in size. Thus, we performed pelvic exenteration. Pathological examination revealed that the tumor was a well-differentiated adenocarcinoma invading the sigmoid colon and bladder. We resected it curatively and administered adjuvant chemotherapy postoperatively. No recurrence was observed during 10 months' follow-up.