Case 1
A 61-year-old man visited our hospital with constipation. Colonoscopy revealed a circumferential tumor in the lower rectum, 60 mm from the anal verge (Fig. 1a). Biopsy findings indicated a moderately differentiated tubular adenocarcinoma. Although a complete obstruction was not detected, we could not pass the endoscope to the oral side of the tumor. Enhanced computed tomography (CT) demonstrated a 6.3-cm-long bulky middle to lower rectal tumor and multiple enlarged regional lymph nodes without distant metastasis. The patient was diagnosed with cT3N1M0 stage IIIa rectal cancer according to the Japanese Classification of Colorectal Carcinoma 8th edition [6]. Neoadjuvant chemoradiotherapy involving a combination of pelvic radiation (total of 45 Gy for 5 weeks) and concurrent chemotherapy with irinotecan and S-1 was introduced. Three weeks after completion of the therapy, the patient visited our hospital on an emergency basis complaining of no defecation for several days and was diagnosed with LBO based on CT findings. The tumor exhibited a clinical partial response (cPR) to the NAT according to the New Response Evaluation Criteria in Solid Tumors: Revised RECIST Guideline (version 1.1) [7]. Emergency colonoscopy revealed an obstruction at the lower rectum, where the primary tumor was located. Although the tumor had shrunk, we observed smooth stenosis with growth of fibrous tissue, which seemed to have been caused by the good response to NAT (Fig. 1b). A SEMS (Niti-S Colonic Stent; Taewoong Medical Inc., Gimpo-si, Korea) 8 cm in length by 18 mm in diameter was placed across the obstruction as a BTS (Fig. 1c). The patient’s symptoms dramatically improved, and he was discharged uneventfully 3 days after SEMS placement. Laparoscopic low anterior resection with diverting ileostomy was performed 3 weeks after SEMS placement. The duration of the operation was 265 min, and the blood loss volume was very small. The pathological diagnosis was moderately differentiated adenocarcinoma, T3 (SS), INFb, ly1, v2, PN1a, pPM(−), pDM(−), pRM(−), pN0, and stage IIA (Fig. 2). Most of the tumor cells had been replaced by atypical cells with growth of fibrous tissue and inflammatory cell infiltration (Fig. 3). Histopathologically, the chemoradiotherapeutic effect was grade 2. The patient had an uneventful postoperative course and was discharged 14 days after surgery. Capecitabine plus oxaliplatin (XELOX) was started as adjuvant chemotherapy 5 weeks after surgery. At the time of this writing, the patient had been alive without recurrence for 26 months.
Case 2
A 56-year-old woman presented because of lack of defecation. She underwent colonoscopy, and a circumferential tumor was found in the lower rectum, 45 mm from the anal verge (Fig. 4a). The tumor was diagnosed as cT4bN2M0 stage IIIb rectal cancer. XELOX plus bevacizumab was introduced as NAT. Upon completion of five courses, the patient underwent colonoscopy for evaluation of the response to NAT. Circumferential luminal narrowing was found in the lower rectum, where the primary tumor was located. The shape of the stenosis was smooth and edematous (Fig. 4b). CT findings revealed LBO. The tumor exhibited a cPR to the NAT. We estimated that the stenosis was associated with effective NAT, as in case 1. A SEMS (Niti-S Colonic Stent) 6 cm in length by 18 mm in diameter was placed across the stenosis as a BTS (Fig. 4c). Laparoscopic low anterior resection with diverting ileostomy was performed 6 weeks after SEMS placement. The duration of the operation was 308 min, and the blood loss volume was very small. The pathological diagnosis was moderately differentiated adenocarcinoma, T3 (SS), INFb, ly1, v1, PN0, pPM(−), pDM(−), pRM(−), pN0, and stage IIA. Most of the tumor cells were organized by atypical cells with growth of fibrous tissue and inflammatory cell infiltration. Histopathologically, the chemotherapeutic effect was grade 2. The patient had an uneventful postoperative course and was discharged 20 days after surgery. XELOX was started as adjuvant chemotherapy 5 weeks after surgery. At the time of this writing, the patient had been alive without recurrence for 17 months.
Case 3
A 63-year-old woman presented with bloody stool. Colonoscopy revealed a circumferential tumor in the lower rectum, 80 mm from the anal verge. The tumor was diagnosed as cT3N2M0 stage IIIb rectal cancer. mFOLFOX6 plus cetuximab was started as NAT. Upon completion of five courses, the patient visited our hospital on an emergency basis complaining of no defecation for several days. Emergency colonoscopy showed a stenosis in the lower rectum, where the primary tumor was located. CT showed that the tumor had obviously shrunk and that an LBO had developed. The tumor exhibited a cPR to the NAT. We estimated that the stenosis had been caused by effective NAT, as in cases 1 and 2. A SEMS (Niti-S Colonic Stent) 6 cm in length by 18 mm in diameter was placed as a BTS across the stenosis. After SEMS placement, the patient began oral intake and NAT was restarted immediately. Upon completion of six courses, laparoscopic low anterior resection with diverting ileostomy was performed. The duration of the operation was 218 min, and the blood loss volume was very small. The pathological diagnosis was well-differentiated adenocarcinoma, T3 (SS), INFc, ly0, v1, PN1a, pPM(−), pDM(−), pRM(−), pN1 (1/18), and stage IIIa. The tumor cells contained atypical cells with growth of fibrous tissue and inflammatory cell infiltration. Histopathologically, the chemotherapeutic effect was grade 2. The patient had an uneventful postoperative course and was discharged 24 days after surgery. mFOLFOX6 was started after surgery as adjuvant chemotherapy. At the time of this writing, the patient had been alive without recurrence for 11 months.