Takamasa Takahashi

Efficacy Evaluation of Subtotal and Total Gastrectomies in Robotic Surgery for Gastric Cancer Compared with that in Open and Laparoscopic Resections: A Meta-Analysis

Purposes Robotic gastrectomy (RG), as an innovation of minimally invasive surgical method, is developing rapidly for gastric cancer. But there is still no consensus on its comparative merit in either subtotal or total gastrectomy compared with laparoscopic and open resections. Methods Literature searches of PubMed, Embase and Cochrane Library were performed. We combined the data of four studies for RG versus open gastrectomy (OG), and 11 studies for robotic RG versus laparoscopic gastrectomy (LG). Moreover, subgroup analyses of subtotal and total gastrectomies were performed in both RG vs. OG and RG vs. LG. Results Totally 12 studies involving 8493 patients met the criteria. RG, similar with LG, significantly reduced the intraoperative blood loss than OG. But the duration of surgery is longer in RG than in both OG and LG. The number of lymph nodes retrieved in RG was close to that in OG and LG (WMD = −0.78 and 95% CI, −2.15−0.59; WMD = 0.63 and 95% CI, −2.24−3.51). And RG did not increase morbidity and mortality in comparison with OG and LG (OR = 0.92 and 95% CI, 0.69−1.23; OR = 0.72 and 95% CI, 0.25−2.06) and (OR = 1.06 and 95% CI, 0.84−1.34; OR = 1.55 and 95% CI, 0.49−4.94). Moreover, subgroup analysis of subtotal and total gastrectomies in both RG vs. OG and RG vs. LG revealed that the scope of surgical dissection was not a positive factor to influence the comparative results of RG vs. OG or LG in surgery time, blood loss, hospital stay, lymph node harvest, morbidity, and mortality. Conclusions This meta-analysis highlights that robotic gastrectomy may be a technically feasible alternative for gastric cancer because of its affirmative role in both subtotal and total gastrectomies compared with laparoscopic and open resections.

Estimation of the fraction of cancer cells in a tumor DNA sample using DNA methylation.

Contamination of normal cells is almost always present in tumor samples and affects their molecular analyses. DNA methylation, a stable epigenetic modification, is cell type-dependent, and different between cancer and normal cells. Here, we aimed to demonstrate that DNA methylation can be used to estimate the fraction of cancer cells in a tumor DNA sample, using esophageal squamous cell carcinoma (ESCC) as an example. First, by an Infinium HumanMethylation450 BeadChip array, we isolated three genomic regions (TFAP2B, ARHGEF4, and RAPGEFL1) i) highly methylated in four ESCC cell lines, ii) hardly methylated in a pooled sample of non-cancerous mucosae, a pooled sample of normal esophageal mucosae, and peripheral leukocytes, and iii) frequently methylated in 28 ESCCs (TFAP2B, 24/28; ARHGEF4, 20/28; and RAPGEFL1, 19/28). Second, using eight pairs of cancer and non-cancer cell samples prepared by laser capture microdissection, we confirmed that at least one of the three regions was almost completely methylated in ESCC cells, and all the three regions were almost completely unmethylated in non-cancer cells. We also confirmed that DNA copy number alterations of the three regions in 15 ESCC samples were rare, and did not affect the estimation of the fraction of cancer cells. Then, the fraction of cancer cells in a tumor DNA sample was defined as the highest methylation level of the three regions, and we confirmed a high correlation between the fraction assessed by the DNA methylation fraction marker and the fraction assessed by a pathologist (r=0.85; p<0.001). Finally, we observed that, by correction of the cancer cell content, CpG islands in promoter regions of tumor-suppressor genes were almost completely methylated. These results demonstrate that DNA methylation can be used to estimate the fraction of cancer cells in a tumor DNA sample.

Genetic and epigenetic alterations in normal tissues have differential impacts on cancer risk among tissues

Significance The relative importance of genetic and epigenetic alterations in normal tissues on cancer risk was clearly different between esophageal squamous cell and gastric cancers, implying a variety of differences in various types of cancers. The difference observed was well explained by known etiologies: tobacco mutagens for esophageal cancer and chronic inflammation for epigenetic alterations in gastric cancer. The study showed that, if epigenetic and genetic alterations in normal tissues are combined, reflecting their relative contributions, patients with cancer can be precisely discriminated, opening up an avenue to precision cancer risk diagnosis. The study also indicated that for effective cancer prevention, allocation of resources and efforts against genetic and epigenetic alterations should consider their relative contributions. Genetic and epigenetic alterations are both involved in carcinogenesis, and their low-level accumulation in normal tissues constitutes cancer risk. However, their relative importance has never been examined, as measurement of low-level mutations has been difficult. Here, we measured low-level accumulations of genetic and epigenetic alterations in normal tissues with low, intermediate, and high cancer risk and analyzed their relative effects on cancer risk in the esophagus and stomach. Accumulation of genetic alterations, estimated as a frequency of rare base substitution mutations, significantly increased according to cancer risk in esophageal mucosae, but not in gastric mucosae. The mutation patterns reflected the exposure to lifestyle risk factors. In contrast, the accumulation of epigenetic alterations, measured as DNA methylation levels of marker genes, significantly increased according to cancer risk in both tissues. Patients with cancer (high-risk individuals) were precisely discriminated from healthy individuals with exposure to risk factors (intermediate-risk individuals) by a combination of alterations in the esophagus (odds ratio, 18.2; 95% confidence interval, 3.69–89.9) and by only epigenetic alterations in the stomach (odds ratio, 7.67; 95% confidence interval, 2.52–23.3). The relative importance of epigenetic alterations upon genetic alterations was 1.04 in the esophagus and 2.31 in the stomach. The differential impacts among tissues will be critically important for effective cancer prevention and precision cancer risk diagnosis.

Determination of therapeutic strategy for adhesive small bowel obstruction using water-soluble contrast agents: An audit of 776 cases in a single center

Background. Several studies have investigated the diagnostic and therapeutic role of water‐soluble contrast agents in adhesive small bowel obstruction, but there is no clear diagnostic classification for the determination of therapeutic strategy. The aim of this study was to clarify the clinical value of classification using water‐soluble contrast agents in patients with adhesive small bowel obstruction. Methods. Between January 2009 and December 2015, 776 consecutive patients with adhesive small bowel obstruction were managed initially with water‐soluble contrast agents and were included in the study. Abdominal x‐rays were taken 5 hours after administration of 100 mL water‐soluble contrast agents and classified into 4 types. The medical records of the patients with adhesive small bowel obstruction were analyzed retrospectively and divided into 2 groups of patients with complete obstruction (ie, the absence of contrast agent in the colon) with (type I) or without (type II) a detectable point of obstruction and a group with an incomplete obstruction (ie, the presence of contrast agent in the colon) with (type IIIA) or without (type IIIB) dilated small intestine. Results. Types I, II, IIIA, and IIIB were identified in 27, 90, 358, and 301 patients, respectively. The overall operative rate was 16.6%. In the patients treated conservatively (types IIIA and IIIB), 647 patients (98.2%) were treated successfully without operative intervention. The operative rate was 3.4% (n = 12/358) in type IIIA vs 0% (n = 0/301) in the type IIIB group (P = .001). Compared with type IIIA, type IIIB was associated with earlier initiation of oral intake (2.1 vs 2.6 days, P < .001) and a lesser hospital stays (9 vs 11 days, P < .001). Conclusion. This new classification using water‐soluble contrast agents is a simple and useful diagnostic method for the determination of therapeutic strategy for adhesive small bowel obstruction.

Abstract LB-176: Identification of DNA methylation markers to predict esophageal cancer risk for people with carcinogen exposure

Proceedings: AACR Annual Meeting 2014; April 5-9, 2014; San Diego, CA Aberrant DNA methylation of promoter CpG islands (CGIs) is induced in normal cells by aging, chronic inflammation, and exposure to specific carcinogenic factors, and the accumulation level of aberrant DNA methylation can be correlated with risk of cancer development. Also for esophageal squamous cell carcinoma (ESCC), the predominant histologic type in Asian countries, aberrant methylation is present in non-cancerous esophageal mucosae of ESCC patients, and methylation of specific genes is associated with smoking history [Oka et al. Cancer. 2009] and cancer risk [Lee et al. Cancer Prev Res. 2011]. However, for clinical application, markers informative even among drinkers, users of betel quid, and smokers, are required. Here, we aimed to isolate such markers by genome-wide methylation analysis. A total of 311 specimens [51 normal mucosae from healthy subjects (Group 1), 88 normal mucosae of healthy subjects exposed to carcinogen (alcohol, betel quid and tobacco) (Group 2), 94 non-cancerous background mucosae from ESCC patients (Group 3), and 78 cancer tissues from ESCC patients (Group 4)] were collected by endoscopic biopsy. A genome-wide methylation analysis was performed using an Infinium HumanMethylation450 BeadChip array that covered 485,577 CpG sites. Four pooled samples of Group 2 and four pooled samples of Group 3, each pool consisting of four specimens, was prepared. A methylation level of a CpG site for a group of samples was defined as the median of the beta-values of the samples, and that of a locus was defined as a mean of the methylation levels of the probes within the locus. First, we searched for CGI loci differentially methylated between the four pooled samples from Group 2 and those from Group 3 (difference in beta-value > 0.1), and 37 loci were isolated. We were able to design primers for real-time MSP for 12 regions, and measured their methylation levels in the screening set (Group 2, n=38; Group 3, n=40). Seven regions demonstrated higher methylation levels in Group 3 than in Group 2 (P<0.05), and cut-off methylation levels for these regions were determined based upon their ROC. The validation set (Group 2, n=34; Group 3, n=38) was analyzed with the prefixed cut-offs, and the methylation levels of three CGI loci predicted esophageal cancer risk at odds ratios of 5.3 to 6.2 (P<0.05). The results of the present study indicated that the methylation status of the three loci is a candidate marker to predict the risk of ESCC in healthy subjects exposed to carcinogen. Citation Format: Takayoshi Kishino, Takamasa Takahashi, Yi-Chia Lee, Satoshi Yamashita, Toshikazu Ushijima. Identification of DNA methylation markers to predict esophageal cancer risk for people with carcinogen exposure. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr LB-176. doi:10.1158/1538-7445.AM2014-LB-176