Curative Surgery After Neoadjuvant Chemotherapy for Locally Advanced Sigmoid Colon Cancer With Extensive Abdominal Wall Invasion: A Case Report

Locally advanced colon cancer (LACC) can be cured under an appropriate treatment strategy, but the decision on the treatment strategy is also important in terms of long-term prognosis. In cases with extensive abdominal wall involvement, it is especially important to secure adequate margins and repair abdominal wall defects. Recently, neoadjuvant chemotherapy (NAC) for LACC has shown promise in improving the chance of cure with tumor shrinkage. Herein, we report a case of curative surgery after NAC for locally advanced sigmoid colon cancer with extensive abdominal wall invasion. A 50-year-old woman visited our hospital with anemia and an abdominal mass. The diagnosis was LACC of the sigmoid colon with abdominal wall invasion (maximum size, 12 cm), and the clinical stage was stage IIIc (T4b[skin]N1bM0). Resection of the involved skin was expected to cause an extensive abdominal wall defect. At first, a colostomy was performed, followed by NAC with leucovorin, 5-fluorouracil, and oxaliplatin (FOLFOX). Ten cycles of chemotherapy were completed without severe adverse events, and the tumor shrank in size by approximately 39%. We performed a curative sigmoidectomy combined with abdominal wall resection with adequate margins. We reconstructed the abdominal wall defect using a left anterolateral thigh skin flap. Pathological examination revealed mucinous carcinoma involving the transverse colon and abdominal wall, with luminal narrowing in the sigmoid colon. The surgical margins were negative, and the tumor was considered to have had a pathological partial response to NAC. Herein, we report a rare case of curative surgery after NAC with FOLFOX for LACC in the sigmoid colon with extensive invasion of the abdominal wall. We reconstructed the extensive abdominal wall defect with a free anterolateral thigh flap. One of the optional treatment strategies for LACC with extensive abdominal wall invasion was reported in our report.