Tsuyoshi Etoh

Increased DNA Methyltransferase 1 (DNMT1) Protein Expression Correlates Significantly with Poorer Tumor Differentiation and Frequent DNA Hypermethylation of Multiple CpG Islands in Gastric Cancers

We evaluated the significance of aberrant DNA methyltransferase 1 (DNMT1) protein expression during gastric carcinogenesis. The protein expression of DNMT1, Muc2, human gastric mucin, E-cadherin, and proliferating cell nuclear antigen was examined immunohistochemically in gastric cancers and corresponding noncancerous mucosae from 134 patients. The DNA methylation status of the CpG islands of the p16, human MutL homologue 1 (hMLH1), E-cadherin, and thrombospondin-1 (THBS-1) genes and the methylated in tumor (MINT)-1, -2, -12, and -31 clones was examined by methylation-specific polymerase chain reaction and combined bisulfite restriction enzyme analysis. Epstein-Barr virus (EBV) infection was detected by in situ hybridization. Nuclear immunoreactivity for DNMT1 was not detected in any of the noncancerous epithelia, except in proliferative zones (positive internal control), but was found in 97 (72%) of the gastric cancers. DNMT1 overexpression correlated significantly with poorer tumor differentiation (P < 0.001), but not with the phenotype (gastric type versus intestinal type) of the cancer cells. It also correlated significantly with DNA hypermethylation of the CpG islands of the hMLH1 (P = 0.024) and THBS-1 genes (P = 0.043), and with the CpG island methylator phenotype in the gastric cancers (P = 0.007). Reduced E-cadherin expression correlated significantly with poorer tumor differentiation (P = 0.002), DNA hypermethylation of the E-cadherin gene (P < 0.001) and DNMT1 overexpression (P = 0.014). DNMT1 overexpression was also associated with EBV infection (a potential etiological factor in gastric carcinogenesis) but not with the proliferative activity of the cancer cells as indicated by the proliferating cell nuclear antigen-labeling index. These results suggest that DNMT1 overexpression may not be just a secondary effect of increased cancer cell proliferative activity, but may be associated with EBV infection and other etiological factors during gastric carcinogenesis. Furthermore, DNMT1 may play a significant role in the development of poorly differentiated gastric cancers by inducing frequent DNA hypermethylation of multiple CpG islands.

AFP-Producing Gastric Carcinoma: Multivariate Analysis of Prognostic Factors in 270 Patients

Serum α-fetoprotein (AFP) is sometimes high in patients with primary gastric carcinoma, and there is no comprehensive study on the clinicopathologic characteristics and prognostic factors of AFP-producing gastric carcinoma (AGC). To clarify the variables associated with the survival after gastrectomy for AGC, we reviewed the data of patients with AGC and examined the independent prognostic factors. We studied 270 cases of AGC reported in the Japanese literature from June 1982 to March 2001, together with 1 patient of our own experience. The clinicopathologic findings, including serum AFP level, operative curability, and stage of the disease were examined, and factors associated with survival were determined by multivariate analysis. There were 15 stage I tumors (6%), 50 stage II tumors (19%), 51 stage III tumors (20%), and 145 stage IV tumors (55%). The tumors were characterized by frequent serosal invasion (75%), lymph node metastasis (83%), liver metastasis (33%), stage III or IV disease (75%), and noncurative operation (48%). The survival was influenced by the serum AFP level, tumor size, serosal invasion, lymph node metastasis, and liver metastasis, but the independent prognostic factors were operative curability (curative vs. noncurative) and stage of the disease (I, II vs. III, IV). Although the 5-year survival rate and median survival period in all patients were 22% and 14 months, respectively, those in patients with curative gastrectomy were 42% and 29 months, respectively. The results indicate that operative curability and stage of the disease are factors associated with the survival of patients with AGC. Although tumors are often advanced and complicated with liver metastases, long-term survival can be achieved when patients with stage I or II tumor undergo curative gastrectomy.

Short-term surgical outcomes from a randomized controlled trial to evaluate laparoscopic and open D3 dissection for stage II/III colon cancer: Japan Clinical Oncology Group Study JCOG 0404.

Objective:A randomized controlled trial to confirm the non-inferiority of laparoscopic surgery to open surgery in terms of overall survival was conducted, and short-term surgical outcomes are demonstrated. Background:The efficacy and safety outcome of laparoscopic surgery for clinical stages II/III colon cancer undergoing Japanese D3 dissection are still unclear. Methods:Eligibility criteria included colon cancer; tumor located in the cecum, ascending, sigmoid, or rectosigmoid colon; T3 or T4 without involvement of other organs; N0–2; and M0. Patients were randomized preoperatively and underwent tumor resection with D3 dissection. Safety analyses were conducted by per-protocol set. Results:A total of 1057 patients were randomized between October 2004 and March 2009. By per-protocol set, 524 patients who underwent open surgery and 533 patients who underwent laparoscopic surgery were analyzed. D3 dissection was performed in 521 (99.4%) patients in the open surgery arm and 529 (99.2%) patients in the laparoscopic surgery arm. Conversion to open surgery was needed for 29 (5.4%) patients. Patients assigned to laparoscopic surgery had less blood loss (P < 0.001), although laparoscopic surgery lasted 52 minutes longer (P < 0.001). Laparoscopic surgery was associated with a shorter time to pass first flatus, decreased use of analgesics after 5 postoperative days, and a shorter hospital stay. Morbidity [14.3% (76/533) vs 22.3% (117/524), P < 0.001] was lower in the laparoscopic surgery arm. Conclusions:Short-term surgical safety and clinical benefits of laparoscopic D3 dissection were demonstrated. The primary endpoint will be reported after the primary analysis, planned for 2014.

Laparoscopic sentinel node navigation achieved by infrared ray electronic endoscopy system in patients with gastric cancer

BackgroundThe sentinel node (SN) concept has attracted considerable attention recently for the treatment of patients with early gastric cancer (EGC). This study evaluated the feasibility of laparoscopic SN navigation achieved by means of an infrared ray electronic endoscopy (IREE) system with indocyanine green (ICG) injection in patients with EGC.MethodsLaparoscopic SN navigation was performed for 16 patients with preoperatively diagnosed EGC. After identification of SNs, routine laparoscopically assisted distal gastrectomy with lymphadenectomy was performed. Lymph nodes were examined histologically for metastasis by hematoxylin and eosin staining on one section of each node.ResultsOne or more SNs and lymphatic basins were detected in all 16 patients. The average number of SNs detected was 2.9. Lymph node metastasis was found in 2 of the 16 patients (13%). In one of these two patients, lymph node metastasis was found in SNs. In the other patient, metastasis was found in a non-SN rather than a SN, but in the same lymphatic basin. The accuracy of this detection method was 94%, and there was one false-negative case. No adverse events occurred after injection of ICG.ConclusionLaparoscopic SN navigation by means of IREE combined with ICG injection is feasible for patients undergoing laparoscopic surgery for EGC.

Hematogenous Metastasis in Gastric Cancer Requires Isolated Tumor Cells and Expression of Vascular Endothelial Growth Factor Receptor-1

Purpose: Recent studies of cancer metastasis have focused on the role of premetastatic gene expression and circulating tumor cells. We did a blind prospective study in gastric cancer to assess the significance of isolated tumor cells (ITC) and to test the hypothesis that vascular endothelial growth factor receptor-1 (VEGFR-1) is expressed within the bone marrow at tumor-specific, premetastatic sites. Experimental Design: Both bone marrow and peripheral blood samples from 810 gastric cancer patients were collected at the Central Hospital, National Cancer Center (Tokyo, Japan). The samples were transferred to Kyushu University Hospital (Beppu, Japan) where they were analyzed by quantitative real-time reverse transcription-PCR for three epithelial cell markers, carcinoembryonic antigen, cytokeratin-19, and cytokeratin-7, as well as VEGFR-1. Results: ITCs were observed in peripheral blood and bone marrow even in early stages of gastric cancer. The frequency of ITC in bone marrow was significantly associated with the stage of disease by ANOVA (P < 0.01). Gastric cancer metastasized when ITCs were observed in the presence of VEGFR-1. In the 380 patients who were ITC negative and showed low VEGFR-1 expression, synchronous (at the time of surgery) and heterochronous (recurrent) metastases were not observed. Conclusions: ITCs circulate even in early stages of disease. Furthermore, elevated expression of VEGFR-1 facilitates the establishment of hematogenous metastases in gastric cancer. This study indicates that the simultaneous presence of ITC and VEGFR-1 expression at premetastatic sites is clinically significant for disease progression.

Long-term quality of life after laparoscopy-assisted distal gastrectomy for gastric cancer

BackgroundLaparoscopy-assisted distal gastrectomy (LAG) is gaining acceptance for treating early gastric cancer. However, the long-term quality of life after LAG for gastric cancer is unknown. This study compared the long-term quality of life after LAG versus open distal gastrectomy (ODG) for early gastric cancer.MethodThis study included 53 patients who underwent LAG and 37 patients who underwent ODG for treatment of early gastric cancer. Quality of life was evaluated on the basis of a 22-item questionnaire that addressed food tolerance and mental and physical conditions, scored on a scale of 1–3.ResultsThe mean follow-up periods after LAG and ODG were 99.3 and 97.0 months, respectively. Although the majority of patients who had undergone LAG were consuming a normal diet and had weight loss of less than 5 kg, all 22 items and the total score of the LAG group were comparable to those of the ODG group. However, the incidence of postoperative intestinal obstruction was significantly lower in the LAG group than in the ODG group (1% vs. 13%, p < 0.05).ConclusionsLAG is equivalent to ODG with respect to long-term quality of life and is associated with a reduced incidence of postoperative intestinal obstruction.

Minimally invasive approaches for gastric cancer—Japanese experiences

Since development of laparoscopy‐assisted distal gastrectomy with lymph node dissection in 1991 in Japan, laparoscopic gastrectomy (LAG) is improving and evolving. Recently, advanced LAG techniques including D2 lymph node dissection or anastomosis after total gastrectomy have been developed. Retrospective and prospective multicenter studies have been conducted for early and non‐early gastric cancers to establish high‐quality evidence. This review summarizes the current trends of minimally invasive approaches for gastric cancer based on current Japanese experiences. J. Surg. Oncol. 2013;107:282–288.

Identification of the high-risk group for metastasis of gastric cancer cases by vascular endothelial growth factor receptor-1 overexpression in peripheral blood.

Identification of an isolated tumour cell with metastatic ability is important for predicting the recurrence and prognosis of gastric cancer. A biological marker for evaluating the metastatic ability of gastric cancer cells has not yet been identified. We assessed vascular endothelial growth factor receptor-1 mRNA expression by quantitative real-time reverse transcriptase-polymerase chain reaction. Vascular endothelial growth factor receptor-1 mRNA in peripheral blood was more highly expressed in perioperative metastasis-positive and postoperative recurrence cases than in normal control cases, early cancer cases and nonmetastatic advanced cancer cases. The peripheral blood vascular endothelial growth factor receptor-1 mRNA-positive group was associated with advanced clinical stage, deep invasion beyond the muscularis propria, lymphatic involvement, vascular involvement, lymph node metastasis, positive peritoneal lavage cytology, preoperative metastasis and postoperative recurrence. Flow cytometry analysis disclosed that vascular endothelial growth factor receptor-1 expressing cells in the peripheral blood were more abundant in cancer cases with metastases than in cases without metastases. Our data suggest that the amount of positive cells may provide information on the clinical features of gastric cancer, especially in regard to gastric cancer metastasis.

Long-term outcome of laparoscopic wedge resection for gastric submucosal tumor compared with open wedge resection.

Little is known about the outcomes of laparoscopic wedge resection (LWR) in comparison with conventional open wedge resection (OWR) for gastric submucosal tumor. Outcomes of 21 patients who underwent LWR (n=14) or OWR (n=7) for gastric submucosal tumor between 1993 and 2004 were investigated. We compared the short-term and long-term operative results between the 2 groups. LWR showed several advantages over OWR for gastric submucosal tumor: less blood loss, lower fever on day 1, lower analgesic usage rate, earlier first postoperative flatus and oral intake, lower leukocyte count on days 1 and 7, and lower C-reactive protein level on days 1 and 3. All patients, except 2 with histologically diagnosed high-risk gastrointestinal stromal tumor, survived during the mean follow-up period of 60 months. LWR is feasible for the management of patients with gastric submucosal tumor.

Laparoscopic Gastrectomy for Cancer

There are three procedures for the management of early gastric cancer (EGC): laparoscopic wedge resection (LWR), intragastric mucosal resection (IGMR), and laparoscopic gastrectomy. LWR or IGMR can be applied to treat EGC without the risk of lymph node metastasis. However, owing to the recent technical advances in endoscopic mucosal resection for EGC, the use of laparoscopic local resection for these lesions has gradually decreased. On the other hand, laparoscopic gastrectomy with lymph node dissection, such as laparoscopy-assisted distal gastrectomy, is widely accepted for the treatment of EGC with the risk of lymph node metastasis. To establish the acceptability of laparoscopic gastrectomy with D2 lymph node dissection against advanced gastric cancers, safe techniques and new instruments must be developed. The following advantages of laparoscopic surgery for the treatment of gastric cancer have been well demonstrated: clinical course after operation, pulmonary function, immune response. In the future, laparoscopic surgeons have to design and implement education and training systems for standard laparoscopic procedures, evaluate clinical outcomes by multicentric randomized control trial studies, and clarify the oncological aspects of laparoscopic surgery in basic studies.