Chew-Wun Wu

As life expectancy continues to increase around the world, the use of minimally invasive surgery (MIS) could be beneficial for octogenarian and older gastric cancer patients. A total of 359 gastric cancer patients who underwent curative surgery between March 2011 and March 2015 were enrolled; 80 of these patients (22.2%) were octogenarians and older. Surgical approaches included MIS (50 laparoscopic and 65 robotic) and open surgery (n = 244). Surgical outcomes of MIS and open surgery in octogenarian and older patients were compared with younger patients. Among octogenarian and older patients, relative to open surgery (n = 53), MIS (n = 27) was associated with less operative blood loss, a shorter postoperative hospital stay and similar rates of surgical complications and mortality. For MIS (n = 115), octogenarian and older patients exhibited similar postoperative outcomes to those of younger patients. For open surgery (n = 244), relative to younger patients, octogenarian and older patients experienced longer postoperative hospital stays, a higher rate of wound infection and a higher incidence of pneumonia. MIS for gastric cancer is beneficial and can be performed safely in octogenarian and older patients.

MicroRNAs are derived from endogenous stem-loop precursors, and play important roles in various biological processes. From next-generation sequencing data, it is suggested that both the 5p-arm and 3p-arm of mature miRNAs could be generated from a single miRNA hairpin precursor; however, the current miRNA databases fail to provide comprehensive arm annotation features, which could result in ambiguous and incomplete analyses. In the present report, we have annotated over 99.7% of miRNAs with the correct 5p-arm and 3p-arm features. The length distribution of all annotated miRNAs is around 22 nucleotides; however, the 5p-arm miRNAs seem to be longer than those of the 3p-arm, which is evident in the 23-nucleotide group. Our study effort generates comprehensive miRNA arm-feature annotation which can be utilized for better interrogation of miRNAs. In further analysis of human gastric cancer tissues, we identified 38 down-regulated miRNAs and 22 up-regulated arm-specific miRNAs using this new comprehensives miRNA list.

For many years, the understanding of gastrointestinal stromal tumors (GISTs), which are the most common mesenchymal tumors of the gastrointestinal tract, has been very limited. However, it is now possible to provide a more precise definition through the use of pathology classification and molecular techniques. Coupled with the advancement of clinical practice, especially the development of targeted therapy, there is now a much better insight into its treatment. At present, organizations such as the National Comprehensive Cancer Network in the USA and the European Society for Medical Oncology in Europe have established a consensus and drawn up guidelines for the diagnosis, treatment, and follow-up of GISTs. With experts coming from various districts in Taiwan and combining the most recent clinical data and experiences, the Taiwan Surgical Society of Gastroenterology drafted the first national GIST treatment guidelines after a consensus meeting in 2007. Following subsequent advances in GIST diagnosis and treatment, further revisions and modifications have been made to the original guidelines. We present here the updated consensus and recommendations of the Taiwan Surgical Society of Gastroenterology for the diagnosis and treatment of GIST. We hope these guidelines can help enhance the quality of diagnosis, treatment, and care of patients with GIST in Taiwan.

Splenectomy is the most common combined organ resection in the surgical management for gastric cardia cancer. The role of combined splenectomy is still controversial. From January 1998 to December 2006, a total of 174 patients received radical total gastrectomy for advanced adenocarcinoma of cardia. Patients with previous gastric surgery or tumor invasion of pancreas or spleen were excluded. Among them, 115 patients were enrolled in this study. Patients were divided into group 1 (splenectomy, n=47) and group 2 (spleen preservation, n=68). Their clinicopathological characteristics were compared. Multivariate analysis showed that only tumor size and lymphovascular invasion were two independent indicators of survival. The surgically-related morbidity and mortality rates were similar between the two groups. Among the 3 patients with splenic hilar lymph nodes metastasis, all of them had large tumor size (=4cm), advanced stage (stage III and IV) and tumor center located at the posterior wall of stomach. The 5-year overall survival for advanced cancer was similar (57.1% vs. 60.2%, p=0.681). Splenectomy does not improve overall survival in the management of advanced gastric cardia cancer. Splenectomy has limited clinical benefits except for large advanced tumors located at the posterior wall of stomach.

Radical gastrectomy remains the primary treatment for gastric cancer without distant metastasis. However, anastomotic leakage and extended lymph node dissection might cause additional morbidity and related mortality. From January 1988 to December 2004, 2076 patients with gastric cancer underwent radical gastrectomy at Taipei Veterans General Hospital. The risk factors for anastomotic leakage, including clinicopathological factors, operative procedures, combined organ resection, operating time, blood loss, and associated disease, were analyzed. The various methods used to measure anastomotic leakage and the clinical courses of different sites of anastomotic leakage were compared. The overall complication rate was 18.7% and the incidence of anastomotic leakage was 2.7% (n=57). The anastomotic leakage-related mortality rate was 21.1% (n=12). Older age (> or =65 years), longer operating time, more blood loss, and co-morbidities were the precipitating factors. Adequate drainage was the treatment approach used for anastomotic leakage. The incidence of anastomotic leakage was reduced during the later period of the study (3.4% vs. 1.8%). Only in an institute with a well-established training program and high volume of gastric cancer patients can we improve the surgical skills and accumulate the experiences with management of anastomotic leakage that make radical gastrectomy safer.

Signet ring cell carcinoma and mucinous carcinoma are mucin-producing gastric cancers. Their clinicopathological difference was obscure. From December 1987 to July 2005, a total of 1612 gastric cancer patients received curative surgery, 128 patients with signet ring cell carcinoma and 48 with mucinous carcinoma were enrolled in this study. Clinicopathological data were compared between the two groups. Early stage (stage I and II) patients with mucinous carcinoma were associated with more male predominant (p = 0.002), larger tumor size (p = 0.020), deeper cancer invasion (p < 0.001), and a worse 5-year overall survival (63.6% vs 88.2%, p = 0.012) than those with signet ring cell carcinoma. There was no significant difference between the two groups with advanced stage in 5-year overall survival. There is no significant difference in the initial recurrence pattern between the two groups. Patients with mucinous carcinoma had different biological behaviors with those with signet ring cell carcinoma, in particular early stage, hence had a worse survival.

The incidence of adenocarcinoma of the esophagogastric junction (AEG) is rapidly increasing. We evaluated the clinicopathological difference and outcomes of Taiwanese patients with AEG according to the Siewert classification. Data were prospectively collected between December 1987 and July 2007. Two hundred thirty-one patients underwent curative resection of AEG at Taipei Veterans General Hospital and were divided into different Siewert types. The clinicopathological characteristics, operative morbidity, survival, and initial recurrence pattern were compared between the different types. Fifty-one type II and 180 type III cancer patients were studied. Subtotal esophagectomy via a left thoracotomy (19.6% vs 2.8%), smaller tumor size (4.43 ± 2.04 vs. 5.35 ± 2.03 cm), and more combined organ resection (60% vs. 43.1%) were more common in type II than type III cancer. Multivariate analysis showed that three independent risk factors for death were gender, tumor size, and lymphovascular invasion. There were long-term survivors among the patients with lesser curvature site lymph node metastasis, whereas metastasis to the lymph nodes of the distal stomach and along the greater curvature site was associated with poor prognosis. The 5-year survival was similar between type II and type III cancer (59.6% vs. 63.5%, P = 0.947). Lymphovascular invasion, tumor size, and gender were determined to be three independent factors of survival after curative resection for AEG, and Siewert type was not associated with differences in survival.

MicroRNAs (miRNAs) are a class of endogenous small non-coding RNAs that have been shown to be aberrantly expressed in many human carcinomas. Of these miRNAs, miR-21 appears to be important in tumorigenesis given its up-regulation in almost all types of human cancer examined. However, its association with the clinicopathological features of human gastric cancer has yet to be addressed. Cancer tissues and corresponding normal tissues from 37 patients with gastric cancer were examined for the expression level of miR-21 using quantitative PCR and the clinical relevance of miR-21 was statistically analyzed. miR-21 was overexpressed in 92% (34/37) of the gastric cancer samples examined. However, the patients with higher miR-21 expression did not have a worse prognosis. miR-21 could serve as an efficient diagnostic marker for gastric cancer, but does not affect the clinical prognosis of gastric cancer patients.

Hemorrhage occurs in 15-25% of duodenal ulcers, mostly on the posterior wall of the proximal duodenum. Erosion of the gastroduodenal artery is responsible for serious hemorrhages. Therefore, the relationship between bile duct and gastroduodenal artery should be discerned to prevent bile duct injury. Cadavers from 52 Chinese adults (44 males, 8 females) were dissected for the anatomic relationships of the GDA and bile duct. The gastroduodenal artery has many possible origins, with the common hepatic artery (92.3%) the most common. The mean distance between gastroduodenal artery and pylorus was 2.7 cm; arterial length (from its origin) was 1.2 cm. The relationships between gastroduodenal artery and bile duct could be divided into 4 anatomic types according to Prudhomme's classification. We found 22 samples (42%) of Type 1; 10 samples (19%) of Type 2; 14 samples (27%) of Type 3 (in 8 samples of Type 3, there was about 8mm thickness of pancreatic tissue between the artery and the bile duct); 6 samples (12%) of Type 4. In 12 cases (24%) there was no interposed pancreatic tissue. These anatomic variations could lead to injury during surgical intervention. Our study provides detailed information about anatomic variability in Chinese adults that may help avoid such injury to the common bile duct during duodenal bleeding hemostasis.