Successful resection of rectal cancer and perirectal abscess following systemic chemotherapy and chemoradiotherapy: A case report.

INTRODUCTION AND IMPORTANCE: Perirectal abscesses are uncommon in colorectal cancer. Although abscess infection should be controlled before colorectal cancer treatment, abscess formation makes surgical resection and preoperative treatment difficult. There is currently no established treatment for colorectal cancer with perirectal abscesses. Here, we present a case of rectal cancer with a perirectal abscess that was resected after systemic chemotherapy followed by chemoradiotherapy. CASE PRESENTATION: A 73-year-old man presented to the outpatient clinic with complaints of weight loss and general malaise. Colonoscopy revealed a circumferential tumor 3 cm from the anal verge, and examination of the endoscopic biopsy specimen indicated a well-differentiated tubular adenocarcinoma. Pelvic magnetic resonance imaging revealed a perirectal abscess on the ventral aspect of the rectum. After sigmoid colostomy was performed to control the infection, 4 cycles of panitumumab and modified fluorouracil, leucovorin, and oxaliplatin were administered. After the perirectal abscess disappeared, chemoradiotherapy to the whole pelvis (radiotherapy 45Gy/25 fractions plus tegafur-gimeracil-oteracil) was administered. Total pelvic exenteration with an ileal conduit was performed via open surgery. The pathological diagnosis was well-differentiated tubular adenocarcinoma with complete resection and negative resection margins. No recurrence of cancer has been observed 26 months after surgery. CLINICAL DISCUSSION: Treatment of colorectal cancer with perirectal abscess is difficult to define the extent of resection due to the spread of inflammation. We believe that treatment should address high risk of local recurrence. CONCLUSION: After sigmoid colostomy, complete resection of colorectal cancer with perirectal abscess could be achieved by systemic chemotherapy followed by chemoradiotherapy.