Osamu Motohashi

Endoscopic submucosal dissection (two-point fixed ESD) for early esophageal cancer.

Background:  We have been attempting to improve the safety, reliability and simplicity of endoscopic submucosal dissection for the treatment of early esophageal cancer and to shorten the time needed for this operation.

Duodenal Rare Neuroendocrine Tumor: Clinicopathological Characteristics of Patients with Gangliocytic Paraganglioma

Gangliocytic paraganglioma (GP) has been regarded as a rare benign tumor that commonly arises from the second part of the duodenum. As GP does not exhibit either prominent mitotic activity or Ki-67 immunoreactivity, it is often misdiagnosed as neuroendocrine tumor (NET) G1. However, the prognosis might be better in patients with GP than in those with NET G1. Therefore, it is important to differentiate GP from NET G1. Moreover, our previous study indicated that GP accounts for a substantial, constant percentage of duodenal NETs. In the present article, we describe up-to-date data on the clinicopathological characteristics of GP and on the immunohistochemical findings that can help differentiate GP from NET G1, as largely revealed in our new and larger literature survey and recent multi-institutional retrospective study. Furthermore, we would like to refer to differential diagnosis and clinical management of this tumor and provide intriguing information about the risk factors for lymph node metastasis on GP.

Outcomes and precautions of endoscopic submucosal dissection for undifferentiated-type early gastric cancer.

Objectives: Since the development of techniques for endoscopic submucosal dissection (ESD), the indication range of endoscopic resection (ER) has been extended in early gastric cancer (EGC) treatment. For undifferentiated-type EGC, tumors with an intramucosal depth of invasion, no ulceration and a diameter of 20 mm or less were included in the expanded indications for ER in the Japanese Gastric Cancer Treatment Guidelines 2010. Nonetheless, because of difficulty in detecting lesions that meet the criteria for ER, the number of endoscopically resected cases of undifferentiated-type EGC is less than that of differentiated-type EGC. Methods: We retrospectively investigated the outcomes of ESD in 38 patients with 40 lesions of EGC in which the dominant pathological type was confirmed to be undifferentiated (signet ring cell carcinoma, poorly differentiated adenocarcinoma, mucinous adenocarcinoma) on histological examination of resected specimens. Results: Margin involvement and submucosal infiltration were common noncurative factors. Precise evaluation of the area and depth of lesions is a problem to be solved. Among a total of five patients with involved or uncertain horizontal margins, one of two patients who underwent additional surgery had residual cancer, and one of three patients who were observed had recurrence. Conclusions: Undifferentiated-type EGC with a positive horizontal margin may relapse after ESD. It is therefore essential to precisely evaluate the area of the lesion and to perform resection with an adequate safety margin to decrease the risk of recurrence.

The clinicopathological significance of angiogenesis in hindgut neuroendocrine tumors obtained via an endoscopic procedure

BackgroundAs the World Health Organization grading system for gastroenteropancreatic-neuroendocrine tumors (GEP-NETs) may not always correlate with tumor progression, it is imperative that other independent predictors of tumor progression be established. To identify such predictors, we conducted a retrospective histopathological study of hindgut NETs, obtained from endoscopic procedures, and used statistical analyses to evaluate predictive factors.MethodsWe first obtained clinicopathological data of cases of hindgut NETs. Tissue sections from tumor samples were prepared and subjected to pathological examination. In particular, we calculated the microvessel density (MVD) and lymphatic microvessel density (LMVD) values, and performed appropriate statistical analyses.ResultsA total of 42 cases of hindgut NETs were selected for the study, 41 from the rectum and 1 from the sigmoid colon. Based on the Ki-67 labeling index, 34 cases were classified as NET G1 tumors and 8 as NET G2 tumors. MVD values ranged from 1.4/mm2 to 73.9/mm2 and LMVD values from 0/mm2 to 22.9/mm2. MVD and LMVD were identified as risk factors for venous and lymphatic invasion of hindgut NETs. Moreover, MVD positively correlated with the maximum diameter of the tumor.ConclusionsTumor progression of NETs may cause angiogenesis and lymphangiogenesis, via an unknown mechanism, as well as lymphovascular invasion. Angiogenesis likely plays an important role in occurrence and progression in the initial phase of hindgut NETs.

Risk factors associated with the progression and metastases of hindgut neuroendocrine tumors: a retrospective study

BackgroundThe worldwide incidence of neuroendocrine tumors (NETs) has increased remarkably, with the hindgut being the second most common site for such tumors. However, the mechanisms underlying progression and metastasis of hindgut NETs are unclear. A retrospective study was conducted to elucidate these mechanisms.MethodsClinicopathological data of cases of hindgut NET between April 1996 and September 2015 were analyzed, retrospectively. Patients with neuroendocrine carcinoma were excluded. Formalin-fixed paraffin-embedded tissues of hindgut NET cases were subjected to detailed morphometric and immunohistochemical analyses. Statistical analyses were performed using the non-parametric Mann-Whitney U test, Spearman’s correlation coefficient, and chi-squared test. Multivariate logistic regression analysis was conducted as appropriate for the data set.ResultsFifty-six hindgut NET cases were considered. Microvessel density and lymphatic microvessel density were identified as significant risk factors for venous and lymphatic invasion. There was a positive correlation between microvessel density and the maximum tumor diameter. Multivariate logistic regression analysis revealed that the maximum tumor diameter alone was an independent predictor of lymph node metastasis, whereas lymphovascular invasion and MVD was not the predictor of lymph node metastasis. There were no significant correlations between the Ki-67 labeling index and any of the parameters evaluated including age, sex, the maximum tumor diameter, venous invasion, lymphatic invasion, microvessel density, lymphatic microvessel density, and lymph node metastasis.ConclusionsAngiogenic mechanisms may play important roles in the progression of hindgut NET. Otherwise, the maximum tumor diameter alone was an independent predictor of lymph node metastasis in hindgut NETs. Moreover, our study raises the question of whether the presence of lymphovascular invasion, in endoscopically obtained hindgut NET tissues, is an absolute indication for additional surgery or not.

Usefulness of two-point fixed endoscopic submucosal dissection for superficial esophageal neoplasms

BackgroundEndoscopic submucosal dissection (ESD) is becoming widely regarded as a highly complicated but useful treatment for superficial esophageal neoplasms. However, the technique tends to be associated with adverse events. To evaluate the safety and utility of two-point fixed ESD for superficial esophageal neoplasms, and to discuss future directions.MethodsBetween December 2006 and December 2013, we performed two types of ESD procedures, the two-point fixed ESD that uses continuous countertraction to ensure a sufficient operative field was performed in 107 patients and conventional ESD was performed in 80 patients. Short-term outcomes and adverse events were evaluated. This study was retrospective study from a single institution.ResultsSignificant differences were observed between conventional ESD and the two-point fixed ESD with regard to the operation time, tumor positive and unknown vertical margins of the resected specimen, perforation as an adverse event, mediastinal emphysema, and postoperative stenosis.ConclusionThe two-point fixed ESD is a very useful method compared with the conventional procedure.

The feasibility and safety conversion surgery in stage IV gastric cancer.

164 Background: Conversion surgery could be an option for stage IV gastric cancer when distant metastasis (M1) is disappeared by palliative chemotherapy, however, feasibility, safety and efficacy of surgery after long-term chemotherapy remains unclear. Methods: This retrospective study examined 21 gastric cancer patients who underwent curative conversion surgery between 2001 and 2013. Postoperative complications were evaluated according to the Clavien-Dindo classification. Overall survival (OS) was estimated by Kaplan-Meier method. Results: Median follow-up period (range) was 43.9 months (7.2-72.1 months). The number of M1 factors was one in 17 patients and two in 4, including metastases to non-regional lymph node in 11, peritoneum in 11, and liver in 3. The regimen of chemotherapy was S-1/CDDP in 11 patients, S-1/docetaxel/CDDP in 5, S-1/docetaxel in 2, 5FU/leucovorin/paclitaxel in 1, CPT/CDDP in 1, and S-1 monotherapy in 1. The median duration from initiation of chemotherapy to disappearance of M1 facto...