Bevacizumab is associated with delayed anastomotic leak after low anterior resection with preoperative radiotherapy for rectal cancer: a case report

Background Bevacizumab is an anti-angiogenesis agent used to treat patients with metastatic colorectal cancer and is associated with a variety of complications. We present a patient with rectal cancer who developed a delayed anastomotic leak more than 5 years after undergoing low anterior resection. Case report A 78-year-old man with hematochezia was diagnosed with two synchronous rectal cancers 7 years prior to presentation. Preoperative chemo-radiotherapy was given followed by a very low anterior resection. During follow-up, multiple lymph node metastases developed, which were treated with chemotherapy. First-line chemotherapy, capecitabine, oxizaliplatin, and bevacizumab, was given over 3 years, and second-line chemotherapy, capecitabine, irinotecan, and bevacizumab, was administered over a 3-month period. After the last treatment, the patient presented with pneumaturia and fecaluria. Computed tomography scan revealed extraluminal air between the prostate and rectum, adjacent to the anastomotic site. Ulceration and fistula formation were observed on colonoscopy, and contrast radiography demonstrated a fistula at the anastomotic site. An anastomotic-urethral fistula was diagnosed and transverse colostomy was performed. Conclusions This patient highlights a rare late adverse event at the anastomotic site associated with bevacizumab treatment and preoperative chemo-radiotherapy. Signs and symptoms suggesting anastomotic complications should be thoroughly evaluated during bevacizumab treatment, even long after surgical resection.