Norimoto Nakamura

c-kit and PDGFRA mutations in extragastrointestinal stromal tumor (gastrointestinal stromal tumor of the soft tissue).

Extragastrointestinal stromal tumor (EGIST) is a unique tumor that occurs outside the gastrointestinal tract. EGIST shows a c-kit expression and histologic appearance similar to those of gastrointestinal stromal tumor (GIST). Most GISTs have gain-of-functional mutation of the c-kit gene, and some have mutation of the platelet-derived growth factor receptor-alpha (PDGFRA) gene. However, the frequency of mutation of those genes in EGISTs remains unclear. We examined the clinicopathologic features, prognostic factors, and c-kit and PDGFRA mutation in 39 cases of EGIST. Tumors with high mitotic counts (≥5/50 high power fields) or a high Ki-67 labeling index (≥10%) were significantly correlated with worse prognoses. The c-kit mutation was found in the juxtamembrane domain (exon 11) and the extracellular domain (exon 9) in 12 of 29 cases (41.4%) and 2 of 29 cases (6.9%), respectively. The PDGFRA gene mutation was found at the juxtamembrane domain (exon 12) and the tyrosine kinase domain (exon 18) in one case each. The pattern of kit and PDGFRA mutation in EGIST was essentially similar to that in GIST. Our results suggest that the c-kit and PDGFRA mutations play an important role in the tumorigenesis of EGIST. High mitotic counts and a high Ki-67 labeling index may be useful for predicting the aggressive biologic behavior in EGIST. Furthermore, STI-571, targeting c-kit and PDGFR tyrosine kinase, seems to be a possible therapeutic strategy for EGISTs, especially advanced cases.

Prognostic significance of angiogenesis in gastrointestinal stromal tumor

Angiogenesis is important in the growth and metastasis of various kinds of solid tumors. To investigate the potential role of angiogenesis in gastrointestinal stromal tumor (GIST), an immunohistochemical analysis was performed in 95 cases of GISTs for microvessel density (MVD) and vascular endothelial growth factor (VEGF) expression. MVD was evaluated with immunohistochemical staining for CD31. A high level of MVD was significantly correlated with overexpression of VEGF, tumor location (intestine>stomach), tumor size (≥5 cm), tumor grade (high>intermediate>low grade) (P=<0.0001, 0.0422, 0.0006, 0.0359, respectively). Of the 70 GISTs analyzed, KIT exon 11 mutations were detected in 45 cases (64.3%) and KIT exon 9 mutations in two cases (2.9%). No mutations were found in KIT exons 13 and 17, and platelet-derived growth factor receptor-alpha exons 12 and 18. Interestingly, VEGF expression level was significantly higher in the non-KIT exon 11 mutant group than in the KIT exon 11 mutant group (P=0.0266). In univariate analysis, tumor grade (high grade), tumor size (≥5 cm), mitotic count (≥5/50 high-power fields), Ki-67 labeling index (≥4.6%), MVD (≥7.0/0.95 mm2) and VEGF expression (high) were significantly associated with a shorter period of disease-free survival (P=<0.0001, 0.0199, 0.0055 0.0027, 0.0028 and 0.0302, respectively). In multivariate analysis, tumor grade and MVD were identified as independent worse prognostic factors (P=0.0007, 0.0152, respectively). In conclusion, our results suggest that the evaluation of MVD and VEGF expression is useful for predicting the aggressive biologic behavior of GIST, and that angiogenesis associated with VEGF may play an important role, at least in part, in the progression of GIST.

Short- and long-term outcomes of endoscopic resection of rectal neuroendocrine tumours: analyses according to the WHO 2010 classification.

Abstract Objective Although the World Health Organisation (WHO) defined a novel classification of gastroenteropancreatic neuroendocrine tumours (NETs) in 2010, indications for endoscopic resection of rectal NETs in the guidelines were based on evidence accumulated for carcinoid tumours defined by a previous classification. This study was designed to clarify indications for endoscopic resection of rectal NETs corresponding to the new WHO classifications. Material and methods One hundred-seventy rectal NETs resected endoscopically from April 2001 to March 2012 were histologically re-classified according to the WHO 2010 criteria. The clinicopathological features of these lesions were analysed, and the short- and long-term outcomes of endoscopic resection were evaluated. Results Of the 170 rectal NETs, 166 were histopathologically diagnosed as NET G1 and four as NET G2. Thirty-eight tumours (22.4%) were positive for lymphovascular invasion, a percentage higher than expected. Although the curative resection rate was low (65.3%), en bloc (98.8%) and complete (85.9%) resection rates were high. Modified endoscopic mucosal resection (88.0%) and endoscopic submucosal dissection (92.2%) resulted in significantly higher complete resection rates than conventional endoscopic mucosal resection (36.4%). No patient experienced tumour recurrence, despite the low curative resection rate. Conclusion Despite the low curative resection rate, prognosis after endoscopic resection of rectal NETs was excellent. Prospective large-scale, long-term studies are required to determine whether NET G2 and tumours >1 cm should be included in the indication for endoscopic resection and whether tumours with lymphovascular invasion can be followed up without additional surgery.

Expression level of the mitotic checkpoint protein and G2–M cell cycle regulators and prognosis in gastrointestinal stromal tumors in the stomach

The biological behavior of gastrointestinal stromal tumors (GISTs) ranges from benign to malignant, and the risk of an adverse outcome is correlated with the location of the primary tumor, tumor size, and mitotic counts. Cell cycle regulators are potentially associated with the tumorigenesis and progression of GISTs. Checkpoint with forkhead and ring finger (CHFR) functions as an important checkpoint protein in the early to mid-prophase to regulate mitosis. In this study, we evaluated the expression of CHFR and several cell cycle regulators, including cyclin A, cyclin B1, cdc2, and cdk2, by immunohistochemical staining in 53 cases of primary gastric GISTs, and compared the immunohistochemical results with the clinicopathological factors or the GIST risk grades as modified by Miettinen et al. Of the 53 cases, 18 (34%) showed decreased nuclear CHFR expression. Decreased CHFR expression was correlated with higher mitotic counts [>5/50 high-power fields (HPFs)] (p = 0.039) and a high-risk grade (p = 0.0475), but not with expression of other cell cycle regulators. Higher cyclin A labeling index (LI, >1.5%), cyclin B1 LI (>0.25%), cdc2 LI (>1.16%), Ki-67 LI (>4.9%), mitotic counts (>5/50 HPF) and high-risk grade were each associated with shorter disease-free survival (p = 0.0017, p = 0.003, p = 0.0471, p = 0.002, p < 0.001, and p = 0.0017, respectively). Our results suggest that modified risk grade and increased expression of G2–M regulators such as cyclin A, cyclin B1, and cdc2 are useful for predicting the biological behavior of gastric GISTs. In addition, decreased CHFR expression may play a role in increased proliferative activity of higher grade GISTs.

Prognostic impact of blood vessel invasion in gastrointestinal stromal tumor of the stomach

Gastrointestinal stromal tumors have a wide spectrum of biologic behavior, and occasional cases show liver metastases. The modified risk grade based on tumor size and mitotic counts has been proposed to predict the biologic behavior in gastric gastrointestinal stromal tumors. Blood vessel invasion (BVI) is important in the development of metastasis of various kinds of cancer. The aim of this study was to elucidate the potential role of blood vessel invasion in gastric gastrointestinal stromal tumors. Blood vessel invasion was found in 17 of 122 cases (13.9%) of gastrointestinal stromal tumors, and was significantly correlated with larger tumor size, higher mitotic count and higher modified risk grade. Among 83 cases of primary, localized gastric gastrointestinal stromal tumors available for follow-up information, liver metastasis was observed in 14 cases (16.9%). When blood vessel invasion was positive in the primary tumor, liver metastasis occurred in 80% of cases after the initial surgery, indicating that blood vessel invasion was a significant risk factor of liver metastasis (P < .0001). In univariate and multivariate analyses, tumor size (>5 cm), mitotic count (>5/50 high-power fields) and blood vessel invasion (positive) were significantly associated with a shorter period of disease-free survival. Our results suggest that the evaluation of blood vessel invasion may be useful for predicting the risk of liver metastasis and aggressive biologic behavior of gastrointestinal stromal tumors, and may serve as important information for determining the therapeutic strategies including adjuvant molecular target therapy.

Limited Effect of Rebamipide in Addition to Proton Pump Inhibitor (PPI) in the Treatment of Post-Endoscopic Submucosal Dissection Gastric Ulcers: A Randomized Controlled Trial Comparing PPI Plus Rebamipide Combination Therapy with PPI Monotherapy

Background/Aims The ability of endoscopic submucosal dissection (ESD) to resect large early gastric cancers (EGCs) results in the need to treat large artificial gastric ulcers. This study assessed whether the combination therapy of rebamipide plus a proton pump inhibitor (PPI) offered benefits over PPI monotherapy. Methods In this prospective, randomized, multicenter, open-label, and comparative study, patients who had undergone ESD for EGC or gastric adenoma were randomized into groups receiving either rabeprazole monotherapy (10 mg/day, n=64) or a combination of rabeprazole plus rebamipide (300 mg/day, n=66). The Scar stage (S stage) ratio after treatment was compared, and factors independently associated with ulcer healing were identified by using multivariate analyses. Results The S stage rates at 4 and 8 weeks were similar in the two groups, even in the subgroups of patients with large amounts of tissue resected and regardless of CYP2C19 genotype. Independent factors for ulcer healing were circumferential location of the tumor and resected tissue size; the type of treatment did not affect ulcer healing. Conclusions Combination therapy with rebamipide and PPI had limited benefits compared with PPI monotherapy in the treatment of post-ESD gastric ulcer (UMIN Clinical Trials Registry, UMIN000007435).

Characteristics of Hemorrhagic Peptic Ulcers in Patients Receiving Antithrombotic/Nonsteroidal Antiinflammatory Drug Therapy

Background/Aims Antithrombotic/nonsteroidal antiinflammatory drug (NSAID) therapies increase the incidence of upper gastrointestinal bleeding. The features of hemorrhagic peptic ulcer disease in patients receiving antithrombotic/NSAID therapies were investigated. Methods We investigated the medical records of 485 consecutive patients who underwent esophagogastroduodenoscopy and were diagnosed with hemorrhagic gastroduodenal ulcers. The patients treated with antithrombotic agents/NSAIDs were categorized as the antithrombotic therapy (AT) group (n=213). The patients who were not treated with antithrombotics/NSAIDs were categorized as the control (C) group (n=263). The clinical characteristics were compared between the groups. Results The patients in the AT group were significantly older than those in the C group (p<0.0001). The hemoglobin levels before/without transfusion were significantly lower in the AT group (8.24±2.41 g/dL) than in the C group (9.44±2.95 g/dL) (p<0.0001). After adjusting for age, the difference in the hemoglobin levels between the two groups remained significant (p=0.0334). The transfusion rates were significantly higher in the AT group than in the C group (p=0.0002). However, the outcome of endoscopic hemostasis was similar in the AT and C groups. Conclusions Patients with hemorrhagic peptic ulcers receiving antithrombotic/NSAID therapies were exposed to a greater risk of severe bleeding that required transfusion but were still treatable by endoscopy.