[A Case of Laparoscopic Resection Following Preoperative Chemoradiotherapy of a Locally Recurrent Rectal Cancer after a Prior Endoscopic Curative Resection].

A man in his seventies underwent endoscopic mucosal resection(EMR)of a rectal cancer 3 years ago. Histopathological examination showed that the specimen had been resected curatively. However, a routine follow-up colonoscopy revealed a submucosal mass on the EMR scar. Computed tomography imaging revealed a mass in the posterior wall of the rectum, with suspected invasion of the sacrum. We performed a biopsy during endoscopic ultrasonography and diagnosed a local recurrence of the rectal cancer. After preoperative chemoradiotherapy(CRT), laparoscopic low anterior resection with ileostomy was performed. Histopathological examination revealed invasion of the rectal wall from the muscularis propria to the adventitia and tissue fibrosis at the radial margin, which was devoid of cancerous cells. Subsequently, the patient received adjuvant chemotherapy with uracil/tegafur and leucovorin for 6 months. No recurrence has been reported over a postoperative follow- up period of 4 years. Preoperative CRT may be an effective treatment for locally recurrent rectal cancer after endoscopic resection.

[A Case Report of Rectal MiNEN Laparoscopic Resection].

A 74-year-old woman underwent colonoscopy for positive fecal occult blood test. A colonoscopy revealed a Type 1 tumor in the rectosigmoid region. The tumor was diagnosed as well-differentiated adenocarcinoma(tub1)by biopsy. Laparoscopic high anterior resection was performed. The final diagnosis was MiNEN(adenocarcinoma:NEC=6:4), RS, pT4a(SE), INF c, Ly1c, V1b, Pn1b, BD2, pN2a(5/28), cM0, pStage Ⅲc. All lymph node metastases were of NEC origin. This case was considered to be at high risk of recurrence and require adjuvant chemotherapy focused on NEC. She was referred to an advanced medical institution for carboplatin and etoposide therapy. MiNEN is a rare disease, and has a poor prognosis. In order to establish a therapeutic strategy of MiNEN, it is important to accumulate further cases and evidence.

A case of strongly suspected Lynch syndrome with colorectal neuroendocrine carcinoma.

BACKGROUND: Neuroendocrine cell carcinomas (NEC) of the colon and rectum are uncommon, representing ~ 0.1% of all colorectal carcinomas. They are associated with a much worse prognosis compared to adenocarcinoma of the colon and rectum, as death occurs in approximately half of all patients within 1 year. Lynch syndrome (LS) is the most common cause of inherited colorectal cancer, accounting for 2-4% of newly diagnosed colorectal cancer cases. This case is extremely rare which was strongly suspected LS as the background, and NEC as the histological type of colorectal cancer. CASE PRESENTATION: The patient was a 44-year-old man presenting with vomiting as the main complaint. He had undergone ileocecal resection for cecal cancer at age 29. The diagnosis was obstructive descending colorectal cancer, and colonoscopy revealed tumors in the rectum and sigmoid colon in addition. Due to multiple occurrences of colorectal cancer and its prevalence in the patient's family, LS was suspected. The operation which was a subtotal proctocolectomy was performed. Pathological analysis revealed complete curative resection and the descending colon cancer of the obstructed portion was at the most advanced pathological Stage IIIC in UICC TNM classification, and the tissue type was a NEC. The Ki-67 index was 70%. The results of the microsatellite instability (MSI) test showed high-frequency MSI. The BRAF V600E variant was negative. The immunoexpression of MLH1 was positive, MSH2 was negative, PMS2 was positive, and MSH6 was negative. CONCLUSIONS: Extended surgery is recommended for incipient colorectal cancer in LS cases in order to reliably reduce the risk of developing metachronous colorectal cancer. The survival outcome of surgery alone on digestive tract NECs, even locoregional lesions that are completely resection, is extremely poor. It is currently unclear if digestive tract NECs develop more readily in patients with LS. The accumulation of additional cases is necessary.

A Phenylfurocoumarin Derivative Reverses ABCG2-Mediated Multidrug Resistance In Vitro and In Vivo.

The ATP-binding cassette subfamily G member 2 (ABCG2) transporter is involved in the development of multidrug resistance in cancer patients. Many inhibitors of ABCG2 have been reported to enhance the chemosensitivity of cancer cells. However, none of these inhibitors are being used clinically. The aim of this study was to identify novel ABCG2 inhibitors by high-throughput screening of a chemical library. Among the 5812 compounds in the library, 23 compounds were selected in the first screening, using a fluorescent plate reader-based pheophorbide a (PhA) efflux assay. Thereafter, to validate these compounds, a flow cytometry-based PhA efflux assay was performed and 16 compounds were identified as potential inhibitors. A cytotoxic assay was then performed to assess the effect these 16 compounds had on ABCG2-mediated chemosensitivity. We found that the phenylfurocoumarin derivative (R)-9-(3,4-dimethoxyphenyl)-4-((3,3-dimethyloxiran-2-yl)methoxy)-7H-furo [3,2-g]chromen-7-one (PFC) significantly decreased the IC50 of SN-38 in HCT-116/BCRP colon cancer cells. In addition, PFC stimulated ABCG2-mediated ATP hydrolysis, suggesting that this compound interacts with the substrate-binding site of ABCG2. Furthermore, PFC reversed the resistance to irinotecan without causing toxicity in the ABCG2-overexpressing HCT-116/BCRP cell xenograft mouse model. In conclusion, PFC is a novel inhibitor of ABCG2 and has promise as a therapeutic to overcome ABCG2-mediated MDR, to improve the efficiency of cancer chemotherapy.

[Bladder-Sparing Surgery with Preoperative Chemotherapy for Rectal Cancer with Urinary Bladder Involvement-A Case Report].

A 65-year-old male was diagnosed with rectal cancer invading the urinary bladder, swollen para-aorticlymph nodes, and multiple liver metastases in abdominal CT. After 8 courses of mFOLFOX6 plus panitumumab, the rectal cancer, para-aortic lymph nodes metastasis, and liver metastases decreased significantly in size. Rectal cancer and liver metastases were considered resectable, hence low anterior resection of the rectum was performed. Intraoperative frozen section analysis showed negative metastaticinvolvement of the para-aorticlymph nodes and surgical margins of the urinary bladder; therefore, the urinary bladder was completely preserved. Partial resection of the liver was performed 2 months later. In conclusion, the patient showed good surgical and quality of life results. Thus, the bladder-sparing strategy with preoperative chemotherapy could be considered for appropriately selected rectal cancer patients with urinary bladder involvement.

The indole compound MA-35 attenuates tumorigenesis in an inflammation-induced colon cancer model.

In inflammatory bowel disease, chronic inflammation results in the development of colon cancer known as colitis-associated cancer. This disease is associated with tumor necrosis factor-α (TNF-α) signaling. In addition, intestinal fibrosis is a common clinical complication that is promoted by transforming growth factor ß1 (TGF-ß1). In our previous study, MA-35 attenuated renal fibrosis by inhibiting both TNF-α and TGF-ß1 signaling. This study aimed to identify the possible antitumor effects and antifibrotic effects of MA-35 using an AOM/DSS mouse model. MA-35 was orally administered every day for 70 days in the AOM/DSS mouse model. There was no difference in weight loss between the AOM/DSS group and the AOMDSS + MA-35 group, but the disease activity index score and the survival rate were improved by MA-35. MA-35 blocked the anemia and shortening of the colon induced by AOM/DSS. MA-35 reduced the macroscopic formation of tumors in the colon. In the microscopic evaluation, MA-35 reduced inflammation and fibrosis in areas with dysplasia. Furthermore, the TNF-α mRNA level in the colon tended to be reduced, and the interleukin 6, TGF-ß1 and fibronectin 1 mRNA levels in the colon were significantly reduced by MA-35. These results suggested that MA-35 inhibited AOM/DSS-induced carcinogenesis by reducing inflammation and fibrosis.

[A Small Rectal Neuroendocrine Tumor of Less Than 5mm with Lymph Node Metastasis].

According to the treatment guideline for rectal neuroendocrine tumor(NET), tumor with a diameter ofC10mm should be resected endoscopically, while tumor with a diameter of>10mm should be resected surgically with lymph node dissection. We experienced a case of a rectal NET with a diameter of 5mm with lymph node metastasis. A 69-year-old man underwent colonoscopy for positive fecal occult blood test. The colonoscopy revealed a submucosal tumor(SMT)with a diameter of 5 mm in the lower rectum. An endoscopic mucosal resection(EMR)was performed after SMT was diagnosed as NET by biopsy. Histopathological findings were NET-G1, 4.5×2.5 mm, v(+), ly(+). Then, laparoscopically assisted rectal resection with D2 lymph node dissection was performed. In histopathological examination, no tumor residue was observed in the specimu; however, a regional lymph node metastasis was detected. Risk factors of lymph node metastasis with rectal NET are a diameter of>10 mm, recessed or ulcerated surface, and lymphovascular invasion. However, we have to keep in mind that lymph node metastasis may occur even in small rectal NET with a diameter of ≤10mm.