A 34-year-old male was referred to our hospital with abdominal pain and diagnosed with obstructive transverse colon cancer. Colonoscopy revealed a circumferential tumor in the transverse colon, and histopathological examination revealed moderately differentiated adenocarcinoma (Fig. 1). He had undergone ileo-sigmoid colostomy at his previous hospital. The tumor markers such as CEA and CA19-9 were not elevated. Contrast-enhanced computed tomography (CT) showed a rapidly growing 12 cm tumor with extensive invasion of the anterior abdominal wall and regional lymph node swelling (Fig. 2). There was no evidence of distant metastasis. RAS/BRAF and MSI testing could not be performed due to insufficient tumor volume in biopsy tissue samples.
We diagnosed the tumor as cT4bN2bM0 Stage IIIC locally advanced transverse colon cancer invading the abdominal wall according to the 8th Union for International Cancer Control (UICC) classification and initiated preoperative chemotherapy to reduce the extent of resection and reconstruction of the abdominal wall. Although four courses of the 5-fluorouracil, leucovorin, oxaliplatin, and irinotecan (FOLFOXIRI) regimen were initially planned, he developed an entero-cutaneous fistula due to tumor penetration of the abdominal wall (Common Terminology Criteria for Adverse Events, CTCAE-Grade 4) after two courses of FOLFOXIRI and required emergent construction of a diverting ileostomy (Fig. 3). Colonoscopy and contrast-enhanced CT after emergent surgery showed good tumor shrinkage (Fig. 4). According to Response Evaluation Criteria in Solid Tumors criteria (RECIST), the patient showed a partial response (PR) after preoperative chemotherapy (the reduction rate was about 60%), so the planned chemotherapy was canceled and he underwent radical resection of the tumor.
An upper midline incision was made with a boat-shaped abdominal wall resection. En bloc extended right hemicolectomy was performed with excision of the fistula, ensuring a sufficient margin. The ileostomy and ileo-sigmoid colostomy were also resected, and an ileo-ileostomy, ileo-transverse colostomy, and sigmoid-colocolostomy were performed with functional end-to-end anastomosis. The post-excision defect at the anterior abdominal wall involved 11 × 16 cm of fascia and 6 × 9 cm of skin (Fig. 5). A free ALT perforator flap, measuring 12 × 17 cm of fascia and 5 × 8 cm of overlying skin, was harvested from the right thigh. The descending branch of lateral circumflex femoral artery and vein were anastomosed to the right gastroepiploic artery and vein, and the fascia lata, which was included in the ALT flap, was sutured onto the abdominal wall fascia as inlay fashion to reconstruct the abdominal wall defect (Fig. 6a). The skin was closed, allowing for a complete tensionless defect cover (Fig. 6b).
Histopathology of the resected specimen revealed moderately differentiated adenocarcinoma of the colon with no tumor cells in the abdominal wall tissue but granulation and inflammatory cells, possibly due to the impact of neoadjuvant chemotherapy (post-chemotherapeutic state, therapy effect: Grade 1b). Lymphovascular invasion was observed, but no lymph node metastasis was found (out of 47 dissected lymph nodes). The tumor was diagnosed as Type 3, size 30 × 25 mm, Stage IIA (ypT3N0M0) according to the 8th UICC classification. All resected margins of the specimen were free from adenocarcinoma.
The patient developed intestinal paralysis, but underwent conservative treatment and was discharged on postoperative day 16. He had received the 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX) regimen as adjuvant postoperative chemotherapy, but developed severe mental retardation and dropped out of chemotherapy after the second course, and that is why genetic analysis using the excised specimens is still not available. There has been no evidence of disease 6 months postoperatively.
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