Colorectal cancer is the most common cancer in Japan. Approximately 10%-20% of the patients with colorectal cancer present with large bowel obstruction, and those who present with malignant colonic obstruction (MCO) require urgent decompression because MCO can cause electrolytic fluid imbalance, colonic necrosis, bacterial translocation, and death. Placement of colonic stents (self-expandable metallic stents) for MCO is a major and standard endoscopic treatment that has been available since 2012 in Japan. This review presents the current conditions and future prospects of this procedure based on the literature. The current indication of colonic stent placement is malignant colorectal stenosis. One of the purposes of using stents is palliative treatment; further, its advantages over emergency surgery with colostomy include avoidance of colostomy, relief of obstruction, shorter hospitalization, and better quality of life. In addition, stent placement can also be used as a bridge to surgery since the duration of the hospitalization is shorter and postoperative complications, colostomy rates, and mortality rates are lower with elective than with emergency surgery. Although recent studies have reported low complication rates related to colonic stents, complications may still occur, highlighting the importance of good preparation, adequate staffing, backup systems, and informed consent. The current major problem related to colonic stents is the lack of evidence on patients' long-term prognoses for bridge to surgery purposes, awaiting the results of ongoing clinical research.

Objectives: It has been reported that there is an association between the nutritional condition and the prognosis of cancer. Here, we evaluated the relation between the prognostic nutritional index (PNI) and colorectal cancer (CRC). Methods: A total of 184 patients with CRC who underwent curative surgery from October 2011 to December 2012 at the Osaka University Hospital were investigated. According to the median PNI value of our data set, patients were classified into a high-PNI (≥46) group and a low-PNI (<46) group. The relationship between the PNI and the disease-free survival (DFS) and overall survival (OS) was analyzed by a Cox regression model. Results: A low PNI was significantly associated with poor DFS (P = 0.006) and OS (P < 0.001). A multivariate analysis showed that low PNI, venous invasion (present), and tumor location (rectum) were independent risk factors for recurrence. Low PNI, advanced age, and venous invasion were found to be independent risk factors for mortality. Using these clinicopathological factors, we developed nomograms to predict DFS and OS. The concordance index was 0.828 for DFS and 0.756 for OS. Conclusions: A low PNI is a prognostic indicator for recurrence and mortality in CRC. Nomograms constructed by clinicopathological factors including the PNI can provide individual prognostic outcomes.

Objectives: The variable-stiffness colonoscope is reportedly useful for making colonoscope insertion easier. However, this function is not associated with all colonoscopes. We developed a variable-stiffness stylet that can be inserted into the endoscope instrumentation channel to change the rigidity of the endoscope. Methods: We developed a stylet with adjustable stiffness and investigated its utility in colonoscope insertion using an ex-vivo model. Four endoscopists performed 24 colonoscope insertions, alternating between using the stylet (Stylet method) and the conventional method. We assessed insertion rate, rate of applying abdominal compression, and insertion time between the two groups. Results: In all procedures, the endoscope was inserted up to the cecum. There were significantly fewer external abdominal compressions with the Stylet method (1/12, 8.3%) compared to the conventional method (6/12, 50%). The insertion time was shorter with the Stylet method (140.9 ± 53.7 s) compared to the conventional method (181.3 ± 64.9 s). Conclusions: Using the variable-stiffness stylet, currently under development, resulted in significantly fewer external abdominal compressions and tended to have shorter insertion time.

Objectives: Colorectal cancer (CRC) surgery after pancreaticoduodenectomy (PD) is difficult to perform, because PD involves dissection and complex reconstruction of the digestive tract. We evaluated the clinical outcomes of CRC surgery in patients with prior PD. Methods: Between January 2008 and March 2018, a total of 1727 patients received CRC surgery at our institution. Of these, 10 had previously undergone PD (PD group). As a control group, 280 patients were collected who had undergone resection without any history of previous abdominal surgery. The PD and control groups were further subdivided into four groups by right or left side. Outcomes of colorectal surgery were investigated in the PD and control groups. Results: The number of harvested lymph nodes was significantly lower in the PD group. In the right colectomy group, distance from the surgical margin was significantly shorter in the PD group. The rate of postoperative complications was higher in the PD group. Peritoneal dissemination originating from pancreatic cancer was found during CRC surgery for one patient, and one patient developed refractory ascites. Three patients died of pancreatic cancer, rectal cancer, and other disease. Seven patients were alive without recurrence. Conclusions: CRC surgery for patients with prior PD can involve difficulty in dissecting lymph nodes and higher postoperative morbidity rates but can provide sufficiently curative resection for CRC.

Objectives: Surveillance colonoscopy after endoscopic resection (ER) for adenomatous polyps reduces the incidence and mortality of colorectal cancer (CRC). However, its significance in the elderly population is uncertain. The study aimed to determine whether surveillance colonoscopy should be discontinued in the elderly population. Methods: We enrolled 105 patients who underwent baseline colonoscopy between January 2004 and December 2009 and were subsequently followed-up over 5 years in our institution. All had diminutive colorectal polyps and were aged <80 years at baseline colonoscopy and ≥80 years at follow-up in May 2018. Patients who had undergone colectomy or who had inflammatory bowel disease, familial adenomatous polyposis, Lynch syndrome, and no diminutive polyps were excluded. The cumulative incidence of the target lesion was evaluated. Histopathological diagnoses included low-grade dysplasia (LGD), high-grade dysplasia (HGD), and carcinoma. Results: The target lesion was detected in 15% (16/105) of the patients. There was no invasive carcinoma; however, two HGDs were detected. There were three lesions that had increased from previously detected diminutive lesions, all of which were LGDs. There were no target lesions detected after 84 years of age, and the cumulative incidence was 0.20. The cumulative incidence was significantly higher in the group with HGD than in the group with no target lesions at baseline colonoscopy. There was no HGD after age 79 years, and the cumulative incidence was 0.019. Conclusion: Surveillance colonoscopy for patients with diminutive polyps may be discontinued after age 79 years.

Background: Treatment with TAS-102 has significantly improved the progression-free survival (PFS) and overall survival (OS) of patients with metastatic colorectal cancer (mCRC). Reportedly, the combination of TAS-102 plus bevacizumab extends the median PFS. The present study aimed to confirm the efficacy and safety of TAS-102 plus bevacizumab (biweekly administration) as third-line chemotherapy for patients with mCRC. Methods/Design: This is a single-arm, open-label, prospective, nonrandomized, multicenter phase II trial conducted in Japan. With a threshold and expected PFS of 2.1 and 3.5 months, respectively, the simulation results showed a sample size of 42 with α = 0.05 (both sides) for 90% power, based on the One-Arm Binomial test using the SWOG statistical tool. If the estimated dropout is 7%-8%, the target sample size is estimated to be 45. The TAS-CC4 study regimen comprised 28-day cycles with biweekly oral administration of TAS-102 (35 mg/m² twice daily on days 1-5 and 15-19 of every 28-day cycle) and bevacizumab (5.0 mg/kg on days 1 and 15). The primary end point is the PFS; secondary end points include response rate (RR), OS, grade ≥3 neutropenia, and genetic alterations (KRAS/BRAF mutations) in the circulating cell-free DNA. Discussion: The present study can contribute to the determination of the effective dosing interval of TAS-102 and bevacizumab in patients with mCRC and is thought to lead to prophylaxis of neutropenia and prolongation of the treatment period.