Exploring ideal operative time for best outcomes in gastric cancer surgery: A multi-institutional study based on KLASS-07 database.

Objective: While a rushed operation can omit essential procedures, prolonged operative time results in higher morbidity. Nevertheless, the optimal operative time range remains uncertain. This study aimed to estimate the ideal operative time range and evaluate its applicability in laparoscopic cancer surgery. Methods: A prospectively collected multicenter database of 397 patients who underwent laparoscopic distal gastrectomy were retrospectively reviewed. The ideal operative time range was statistically calculated by separately analyzing the operative time of uneventful surgeries. Finally, intraoperative and postoperative outcomes were compared among the shorter, ideal, and longer operative time groups. Results: The statistically calculated ideal operative time was 135.4-165.4 min. The longer operative time (LOT) group had a lower rate of uneventful, perfect surgery than the ideal or shorter operative time (IOT/SOT) group (2.8% vs. 8.8% and 2.2% vs. 13.4%, all P<0.05). Longer operative time increased bleeding, postoperative morbidities, and delayed diet and discharge (all P<0.05). Particularly, an uneventful, perfect surgery could not be achieved when the operative time exceeded 240 min. Regardless of ideal time range, SOT group achieved the highest percentage of uneventful surgery (13.4%), which was possible by surgeon's ability to retrieve a higher number of lymph nodes and perform ≥150 gastrectomies annually. Conclusions: Operative time longer than the ideal time range (especially ≥240 min) should be avoided. If the essential operative procedure were faithfully conducted without compromising oncological safety, an operative time shorter than the ideal range leaded to a better prognosis. Efforts to minimize operative time should be attempted with sufficient surgical experience.

Rare Occurrence of Microsatellite Instability in Gastrointestinal Stromal Tumors.

Background and Objectives: This study aimed to objectively determine microsatellite instability (MSI) status using a next-generation sequencing (NGS)-based MSI panel and to resolve the discrepancy regarding whether or not MSI is a rare phenomenon, irrespective of diverse genomic alterations in gastrointestinal stromal tumors (GISTs). Materials and Methods: Genomic DNA was subjected to MSI panel sequencing using an Ion AmpliSeq Microsatellite Instability Assay, as well as to cancer gene panel sequencing using an Oncomine Focus DNA Assay. Results: All of our GIST patients showed microsatellite-stable (MSS) status, which confirmed that MSI status did not affect the molecular pathogenesis of GIST. The KIT gene (79%, 38/48) was the most frequently mutated gene, followed by the PDGFRA (8%, 4/48), PIK3CA (8%, 4/48), and ERBB2 (4%, 2/48) mutations. KIT exon 11 mutant patients were more favorable in responding to imatinib than those with exon 9 mutant or wild-type GISTs, and compared to non-KIT exon 11 mutant GISTs (p = 0.041). The NGS-based MSI panel with MSICall confirmed a rare phenomenon of microsatellite instability in GISTs irrespective of diverse genomic alterations. Conclusion: Massively parallel sequencing can simultaneously provide the MSI status as well as the somatic mutation profile in a single test. This combined approach may help us to understand the molecular pathogenesis of GIST carcinogenesis and malignant progression.

Radical Gastrectomy After Chemotherapy May Prolong Survival in Stage IV Gastric Cancer: A Korean Multi-institutional Analysis.

ABASTRACT: BACKGROUND: Despite the development of newer treatments, the prognosis for patients with stage IV gastric cancer remains grave. This study evaluated the efficacy of gastrectomy following response to chemotherapy in patients with stage IV gastric cancer. METHODS: A total of 419 patients who were diagnosed with stage IV gastric cancer were identified from the multi-institutional Catholic Gastric Cancer Study Group database. The patients were divided into four groups: 212 were in the chemotherapy only (CTx) group, 124 were in the chemotherapy after palliative gastrectomy (G-CTx) group, 23 were in the radical gastrectomy after chemotherapy (CTx-G) group, and 60 were in the best supportive care group. To compensate for the effects of chemotherapy, cases of chemotherapy responsive were analyzed separately. To identify factors affecting survival rates, cure rates for surgery in the surgery group were analyzed. RESULTS: The 3-year survival rate of the CTx-G group was significantly higher than that of the CTx group (42.8 vs. 12.0%, p = 0.001). Moreover, the CTx-G group's 3-year survival rate was greater than that of the G-CTx group (42.8 vs. 37.1%, p = 0.207). Chemotherapy-responsive patients in the CTx-G group had a better 3-year survival rate than those in the G-CTx group (46.1 vs. 18.4%, respectively, p = 0.011). In the surgery group, R0 resection led to a significantly better 3-year survival rate than palliative gastrectomy (61.1 vs. 16.2%, p = 0.003). CONCLUSIONS: Adjuvant surgery might improve the survival rate of patients with stage IV gastric cancer, particularly in R0 resection cases.

Evaluation of the Three Customized MSI Panels to Improve the Detection of Microsatellite Instability in Gastric Cancer.

BACKGROUND: We designed and evaluated the suitability of three customized microsatellite instability (MSI) panels using a combination of mono- and dinucleotide markers to improve the detection of MSI status in 56 matched normal and gastric cancer specimens. METHODS: An MSI analysis was performed to optimize the panel of microsatellite markers to detect instability using two different microsatellite panels: (1) mononucleotide marker panel consisting of mononucleotide markers BAT25, BAT26, BAT40, BAT-RII, NR21, NR22, NR24, and NR27 and (2) dinucleotide marker panel containing D2S123, D5S346, D17S250, D17S261, D17S520, D18S34, and D18S58. The customized panels consisted of five, seven, or ten markers with two, three, or four mononucleotide markers, respectively, among fifteen MSI markers described above to fulfill the MSI-H and MSI-L definition based on the revised Bethesda Guidelines. The "Proposal5" panel consisted of BAT40, BAT26, D18S34, D2S123, and D17S520. "Proposal-7" consisted of "Proposal-5" with BAT25 and D18S58. "Proposal-10" consisted of "Proposal-7" with NR27, D17S250, and D17S261. RESULTS: Immunohistochemical staining for MMR protein expressions such as mutL homolog 1 (MLH1) and mutS homolog 2 (MSH2) revealed that among 56 matched specimens, 13 had defective DNA mismatch repair (MMR) proteins and 43 had proficient MMR proteins. Out of thirteen specimens with defective MMR expression, eight specimens (62%, 8/13) were classified as MSI-H with an instability at ≥ 6 markers and five (38%, 5/13) were MSIL with instability at ≤ 5 markers using all fifteen MSI markers. On the other hand, the analytical sensitivity and specificity of all three customized panels to detect MMR-deficient specimens were 92% (12/13) and 100% (43/43), respectively. In comparison, the sensitivity and specificity of the Bethesda and QMR panels were 62% (8/13) and 100% (43/43). All customized panels could represent the detection of MSI-L tumors rather than the Bethesda and the QMR panels. CONCLUSIONS: The increased sensitivity to detect MSI-unstable tumors with customized panels including BAT40 and D18S34 indicates that precise MSI screening to discriminate MSI-H from MSS and MSI-L may be feasible for gastric cancer.

Integrated analysis of cancer-related pathways affected by genetic and epigenetic alterations in gastric cancer.

BACKGROUND: The profiles of genetic and epigenetic alterations in cancer-related pathways are considered to be useful for selection of patients likely to respond to specific drugs, including molecular-targeted and epigenetic drugs. In this study, we aimed to characterize such profiles in gastric cancers (GCs). METHODS: Genetic alterations of 55 cancer-related genes were analyzed by a benchtop next-generation sequencer. DNA methylation statuses were analyzed by a bead array with 485,512 probes. RESULTS: The WNT pathway was activated by mutations of CTNNB1 in 2 GCs and potentially by aberrant methylation of its negative regulators, such as DKK3, NKD1, and SFRP1, in 49 GCs. The AKT/mTOR pathway was activated by mutations of PIK3CA and PTPN11 in 4 GCs. The MAPK pathway was activated by mutations and gene amplifications of ERBB2, FLT3, and KRAS in 11 GCs. Cell-cycle regulation was affected by aberrant methylation of CDKN2A and CHFR in 13 GCs. Mismatch repair was affected by a mutation of MLH1 in 1 GC and by aberrant methylation of MLH1 in 2 GCs. The p53 pathway was inactivated by mutations of TP53 in 19 GCs and potentially by aberrant methylation of its downstream genes in 38 GCs. Cell adhesion was affected by mutations of CDH1 in 2 GCs. CONCLUSIONS: Genes involved in cancer-related pathways were more frequently affected by epigenetic alterations than by genetic alterations. The profiles of genetic and epigenetic alterations are expected to be useful for selection of the patients who are likely to benefit from specific drugs.

Totally laparoscopic versus laparoscopy-assisted distal gastrectomy: the KLASS-07: a randomized controlled trial.

BACKGROUNDS: Strong evidence is lacking as no confirmatory randomized controlled trials (RCTs) have compared the efficacy of totally laparoscopic distal gastrectomy (TLDG) with laparoscopy-assisted distal gastrectomy (LADG). The authors performed an RCT to confirm if TLDG is different from LADG. METHODS: The KLASS-07 trial is a multi-centre, open-label, parallel-group, phase III, RCT of 442 patients with clinical stage I gastric cancer. Patients were enroled from 21 cancer care centres in South Korea between January 2018 and September 2020 and randomized to undergo TLDG or LADG using blocked randomization with a 1:1 allocation ratio, stratified by the participating investigators. Patients were treated through R0 resections by TLDG or LADG as the full analysis set of the KLASS-07 trial. The primary endpoint was morbidity within postoperative day 30, and the secondary endpoint was quality of life (QoL) for 1 year. This trial is registered at ClinicalTrials.gov (NCT03393182). RESULTS: Four hundred forty-two patients were randomized (222 to TLDG, 220 to LADG), and 422 patients were included in the pure analysis (213 and 209, respectively). The overall complication rate did not differ between the two groups (TLDG vs. LADG: 12.2% vs. 17.2%). However, TLDG provided less postoperative ileus and pulmonary complications than LADG (0.9% vs. 5.7%, P= 0.006; and 0.5% vs. 4.3%, P= 0.035, respectively). The QoL was better after TLDG than after LADG regarding emotional functioning at 6 months, pain at 3 months, anxiety at 3 and 6 months, and body image at 3 and 6 months (all P< 0.05). However, these QoL differences were resolved at 1 year. CONCLUSIONS: The KLASS-07 trial confirmed that TLDG is not different from LADG in terms of postoperative complications but has the advantages to reduce ileus and pulmonary complications. TLDG can be a good option to offer better QoL in terms of pain, body image, emotion, and anxiety at 3-6 months.

JOURNAL/ijos/04.03/01279778-202408000-00031/figure1/v/2024-08-13T152924Z/r/image-jpeg.

How many contralateral papillary thyroid carcinomas can be missed?

BACKGROUND: When surgeons decide to perform lobectomy as the treatment of papillary thyroid carcinomas (PTCs), they must consider the possibility of contralateral cancer. We wanted to determine the incidence of bilateral PTCs (bPTCs) and analyze their characteristics. We also wanted to determine how many patients with bPTC were missed preoperatively. METHODS: From January 2007 to May 2011, a total of 466 patients with PTC who were treated by total thyroidectomy at a single institution were enrolled. Patients were divided into two groups based on bilaterality. The patients with bPTCs were further investigated regarding the preoperative presence of the contralateral tumor. RESULTS: Bilaterality was seen in 29.8 % of PTC patients. In all, 36.8 % of PTCs ≥ 1 cm, and 25.7 % were papillary thyroid microcarcinomas (PTMCs). The presence of PTC in the contralateral lobe was missed in 15.8 % of bPTCs and in 21.3 % of bPTMCs. The rates of preoperatively nondetected contralateral cancer were 4.7 and 5.5 % for PTCs and PTMCs, respectively. Tumor size and multifocality were factors associated with bilaterality (p = 0.014 and p < 0.001, respectively). CONCLUSIONS: Bilaterality is found more frequently when the tumor is large. Multifocality also can help predict the possibility of bilaterality. Therefore, total thyroidectomy may be necessary for patients with a multifocal or large tumor. It should be noted that the presence of a contralateral cancer is missed in 4.7 and 5.5 % of patients with preoperatively diagnosed unilateral PTC and PTMC, respectively.

Clinicopathological features and management strategy for superficial nonampullary duodenal tumors: a multi-center retrospective study.

Purpose: We investigated the clinicopathological features and management for superficial nonampullary duodenal tumors (SNADTs). The safety and feasibility of laparoscopic management, especially laparoscopic endoscopic cooperative surgery (LECS), were evaluated. Methods: A total of 59 patients with SNADTs who underwent operations from January 2009 to December 2018 at all 8 institutions of the Catholic Medical Center were identified in our comprehensive multi-institutional database. Clinicopathological and surgical data on the 4 anatomical regions of the duodenum were collected and compared. Characteristics of conventional laparoscopic procedure (laparoscopy-only) and LECS procedures were also compared. Results: There were significantly more asymptomatic patients with tumors in the first and second vs. third and fourth duodenal regions. Gastrointestinal stromal tumors (GISTs), carcinoids, and ectopic pancreatic tumors were identified in 32, 12, and 5 cases, respectively. Forty-two patients (71.2%) underwent laparoscopy. Of patients undergoing laparoscopy, the LECS group exhibited significantly more endophytic features and smaller tumor sizes (P < 0.001 and P < 0.001, respectively). Although no significant difference in the wedge resection or postoperative complication rate was seen between the 2 groups (P = 0.096 and P = 0.227, respectively), the wedge resection rate was higher, and the complication rate lower, in the LECS group than the conventional laparoscopic surgery group. Conclusion: Most of the SNADTs located in proximal duodenum were detected incidentally. GISTs were the most common diagnoses of SNADTs in all locations. In treating these tumors, laparoscopic resection is safe and feasible. Especially, LECS may be ideal for treating small endophytic tumors, minimizing over-resection and postoperative complications.

The short-term outcomes of conventional and single-port laparoscopic surgery for colorectal cancer.

OBJECTIVE: The aim of this study was to show the safety and feasibility of single-port laparoscopic surgery (SPLS) by comparing its short-term outcomes with those following conventional laparoscopic surgery. SUMMARY BACKGROUND DATA: Single-port laparoscopic surgery maximizes the advantages of laparoscopic surgery, and therefore it can be an ultimate attainment of laparoscopic surgery. However, no comparative study has addressed its role in colorectal cancer. METHODS: Prospectively collected data of patients who had undergone either conventional laparoscopic surgery (n = 106) or SPLS (n = 73) for colorectal cancer between March 2006 and May 2010 were analyzed retrospectively. The short-term outcomes of these 2 operative modalities were compared. RESULTS: Of the 179 study subjects, 103 (57.5%) had colon cancer and 76 (42.5%) had rectal cancer. Various operative methods, from right hemicolectomy to abdominoperineal resection, were used according to location through either conventional laparoscopic or SPLS approach. In its comparison, mean surgical time was greater in the SPLS group (255 vs 276 minutes, P < 0.008). Acquired length of sufficient surgical margins and the number of harvested lymph nodes were comparable. Postoperative recovery was faster in the SPLS group, in terms of shorter time duration before first flatus (SPLS vs conventional laparoscopic surgery; 2.5 ± 1.2 vs 3.2 ± 1.8 days, P = 0.004), earlier initiation of free oral fluids (1.8 ± 2.2 vs 2.6 ± 1.7 days, P = 0.000) and of a solid diet (4.2 ± 2.9 vs 6.5 ± 2.7 days, P = 0.000), less frequent usage of parenteral narcotics (2.2 ± 3.2 vs 3.5 ± 4.0 times, P = 0.029), and shorter hospital stay (9.6 ± 9.6 vs 15.5 ± 9.8 days, P = 0.000). CONCLUSION: This study shows that SPLS is both safe and feasible in colorectal cancer, and that it has equivalent or better short-term outcomes than conventional laparoscopic surgery. Accordingly, the authors conclude that SPLS can be an alternative to conventional laparoscopic surgery for colorectal cancer.

Analysis of the clinicopathologic features of papillary thyroid microcarcinoma based on 7-mm tumor size.

BACKGROUND: We examined the clinicopathologic features of papillary thyroid microcarcinomas (PTMCs) measuring≤7 mm and compared them with those of PTMCs>7 mm. METHODS: Between January 2007 and June 2009, a total of 275 patients with PTMCs underwent surgery. They were divided into two groups. Group I included patients with tumors≤7 mm, and group II included those with tumors>7 mm but ≤10 mm. We compared the two groups' clinicopathologic features. RESULTS: Total thyroidectomy was more often performed in group II (p=0.003). Central lymph node metastases were identified in 30.6% of the patients in group I and in 47.8% of the patients in group II (p=0.005). A statistically significant difference between the two groups was also found for capsule invasion (p<0.0001), extrathyroidal extension (p=0.005), and lymphovascular invasion (p=0.025). On the multivariate analysis, central lymph node metastasis was the only independent factor associated with tumor size. CONCLUSION: A PTMC≤7 mm is less likely to have aggressive features, including central lymph node metastasis, capsule invasion, extrathyroidal extension, and lymphovascular invasion, than a PTMC>7 mm. Because the aggressiveness of PTMC was found mainly in the patients with tumors >7 mm, we think that a cutoff value of 7 mm may be considered the threshold of aggressiveness of PTMCs.

Genetic profiling of somatic alterations by Oncomine Focus Assay in Korean patients with advanced gastric cancer.

Gastric cancer is one of the leading causes of cancer-associated death; however, analysis of its molecular and clinical characteristics has been complicated by its histological and etiological heterogeneity. The present study aimed to estimate somatic mutation profiling in gastric cancer. To do so, targeted next-generation sequencing (NGS) was performed with the Oncomine Focus Assay to compare the clinicopathological characteristics with the mutation profiles in 50 patients with advanced gastric cancer (AGC). Among the 35 hotspot genes and 19 genes for copy number variations (CNVs), 18 single nucleotide variants (SNVs) or small insertions and deletions (14 missense and four frameshift mutations), and 10 amplifications were identified. To examine the association between mutation profiles and clinicopathological characteristics, each element of the clinicopathological characteristics was categorized into three groups: No alteration, PI3K catalytic subunit α (PIK3CA) alterations and alterations other than PIK3CA. Fisher's exact test identified no statistical differences between the clinicopathological characteristics, with the exception of the Tumor-Node-Metastasis (TNM) T stage between the three groups. Cases of AGC with somatic alterations but no PIK3CA exhibited a significant difference in the TNM T stage compared with those with no alterations or PIK3CA alterations (P=0.044). In addition, AGC with PIK3CA alterations was categorized by Lauren's classification to the intestinal type only. The distribution of Lauren's classification in AGC with PIK3CA alterations was statistically different compared with AGC with alterations other than PIK3CA (P=0.028), but not compared with AGC with no alterations (P=0.076). In conclusion, the present study demonstrated a molecular profiling approach that identified potential molecular classifications for gastric cancer and suggested a framework for precision medicine in AGC.

Genetic Characterization of Molecular Targets in Korean Patients with Gastrointestinal Stromal Tumors.

PURPOSE: Gastrointestinal stromal tumors (GISTs) frequently harbor activating gene mutations in either KIT or platelet-derived growth factor receptor A (PDGFRA) and are highly responsive to several selective tyrosine kinase inhibitors. In this study, a targeted next-generation sequencing (NGS) assay with an Oncomine Focus Assay (OFA) panel was used for the genetic characterization of molecular targets in 30 Korean patients with GIST. MATERIALS AND METHODS: Using the OFA that enables rapid and simultaneous detection of hotspots, single nucleotide variants (SNVs), insertion and deletions (Indels), copy number variants (CNVs), and gene fusions across 52 genes relevant to solid tumors, targeted NGS was performed using genomic DNA extracted from formalin-fixed and paraffin-embedded samples of 30 GISTs. RESULTS: Forty-three hotspot/other likely pathogenic variants (33 SNVs, 8 Indels, and 2 amplifications) in 16 genes were identified in 26 of the 30 GISTs. KIT variants were most frequent (44%, 19/43), followed by 6 variants in PIK3CA, 3 in PDGFRA, 2 each in JAK1 and EGFR, and 1 each in AKT1, ALK, CCND1, CTNNB1, FGFR3, FGFR4, GNA11, GNAQ, JAK3, MET, and SMO. Based on the mutation types, majority of the variants carried missense mutations (60%, 26/43), followed by 8 frameshifts, 6 nonsense, 1 stop-loss, and 2 amplifications. CONCLUSIONS: Our study confirmed the advantage of using targeted NGS with a cancer gene panel to efficiently identify mutations associated with GISTs. These findings may provide a molecular genetic basis for developing new drugs targeting these gene mutations for GIST therapy.

Current Status of Bariatric and Metabolic Surgery in Daejeon and Chungcheong Province: Early Experiences after Public Medical Insurance Coverage in 2019.

Purpose: This study aimed to investigate the current status of bariatric and metabolic surgery in Daejeon and Chungcheong province and to describe the early experiences after public medical insurance coverage in 2019. Materials and Methods: Between January 2019 and August 2019, 64 cases of bariatric and metabolic surgery were performed in patients with morbid obesity or uncontrolled type 2 diabetes. We prospectively collected and analyzed data regarding the patients' demographics and comorbidities, surgical results, and early complications. The patient information before and after the insurance coverage was also compared. Results: The number of surgeries in 9 years has been caught up only in the last 8 months after insurance coverage (58 vs. 64 patients). The mean body mass index was 37.7±5.8 kg/m2 (range, 22.7-52.1 kg/m2). The most frequently performed surgery was sleeve gastrectomy (53 cases, 82.8%), followed by Roux-en-Y gastric bypass (9 cases, 14.1%), and adjustable gastric banding (2 cases, 3.1%). Postoperative complications occurred in 6 patients (9.4%), and there was no mortality. The mean operation time (225.3±85.4 vs. 156.1±61.8 min, P<0.001) and postoperative stay (5.9±4.5 vs. 4.3±2.0 days, P=0.013) after the insurance coverage were significantly shorter than those before the insurance coverage. Conclusion: We could assess the patients who had bariatric and metabolic surgery in Daejeon and Chungcheong province after public medical insurance coverage in 2019.

Safety of Laparoscopic Radical Gastrectomy in Gastric Cancer Patients with End-Stage Renal Disease.

PURPOSE: The surgical outcomes of end-stage renal disease (ESRD) patients undergoing radical gastrectomy for gastric cancer were inferior compared with those of non-ESRD patients. This study aimed to evaluate the short- and long-term surgical outcomes of ESRD patients undergoing laparoscopic gastrectomy (LG) and open gastrectomy (OG) for gastric cancer. MATERIALS AND METHODS: Between 2004 and 2014, 38 patients (OG: 21 patients, LG: 17 patients) with ESRD underwent gastrectomy for gastric cancer. Comparisons were made based on the clinicopathological characteristics, surgical outcomes, and long-term survival rates. RESULTS: No significant differences were noted in the clinicopathological characteristics of either group. LG patients had lower estimated blood loss volumes than OG patients (LG vs. OG: 94 vs. 275 mL, P=0.005). The operation time and postoperative hospital stay were similar in both the groups. The postoperative morbidity for LG and OG patients was 41.1% and 33.3%, respectively (P=0.873). No significant difference was observed in the long-term overall survival rates between the 2 groups (5-year overall survival, LG vs. OG: 82.4% vs. 64.7%, P=0.947). CONCLUSIONS: In ESRD patients, LG yielded non-inferior short- and long-term surgical outcomes compared to OG. Laparoscopic procedures might be safely adopted for ESRD patients who can benefit from the advantages of minimally invasive surgery.

Comparison between mononucleotide and dinucleotide marker panels in gastric cancer with loss of hMLH1 or hMSH2 expression.

BACKGROUND: DNA mismatch repair deficiency is an important molecular mechanism of genetic instability in gastric cancer, and a high instability at microsatellites is associated with favorable prognosis. We compared mononucleotide and dinucleotide microsatellite instability (MSI) marker panels in 56 paired gastric tumor and normal samples. METHODS: The mononucleotide marker panel (mono panel) consisted of 8 markers: BAT25, BAT26, BAT40, BAT-RII, NR21, NR22, NR24 and NR27. The dinucleotide marker panel (di panel) contained D2S123, D5S346, D17S250, D17S261, D17S520, D18S34 and D18S58. The NCI panel was used as reference panel. RESULTS: Among 13 gastric tumors showing no hMLH1 or hMSH2 expression, 8 MSI-H (high) and 5 MSI-L (low) were identified. The analytical sensitivities of the NCI, mono and di panels to detect unstable MSI were 61.5% (8/13), 76.9% (10/13) and 84.6% (11/13), respectively. The size change of allele shift was statistically greater in the mono panel than in the di panel (p = 0.02 by Mann-Whitney U-test). The BAT40 (69.2%, 9/13) and D18S34 (76.9%, 10/13) markers showed high sensitivity for determination of MSI status. CONCLUSIONS: To improve the detection rate of MSI in gastric cancer with loss of hMLH1 or hMSH2 expression, the kind of MSI marker may need to be considered more, instead of the repetitive type of marker. Thus, an MSI panel designed with a combination of both BAT40 and D18S34 is suggested for providing more accurate and sensitive MSI analysis in gastric cancer.

Distribution of somatic mutations of cancer-related genes according to microsatellite instability status in Korean gastric cancer.

In studies of the molecular basis of gastric cancer (GC), microsatellite instability (MSI) is one of the key factors. Somatic mutations found in GC are expected to contribute to MSI-high (H) tumorigenesis. We estimated somatic mutation distribution according to MSI status in 52 matched pair GC samples using the Ion Torrent Ion S5 XL with the AmpliSeq Cancer Hotspot panel.Seventy-five (9.8%) somatic variants consisting of 34 hotspot mutations and 41 other likely pathogenic variants were identified in 34 GC samples. The TP53 mutations was most common (35%, 26/75), followed by EGFR (8%, 6/75), HNF1A (8%, 6/75), PIK3CA (8%, 6/75), and ERBB2 (5%, 4/75). To determine MSI status, 52 matched pair samples were estimated using 15 MSI markers. Thirty-nine MS stable (S), 5 MSI-low (L), and 8 MSI-H were classified. GCs with MSI-H tended to have more variants significantly compared with GCs with MS stable (MSS) and MSI-L (standardized J-T statistic  =  3.161 for number of variants; P  =  .002). The mean number of all variants and hotspot mutations per tumor samples only in GCs with MSI-H were 3.9 (range, 1-6) and 1.1 (range, 0-3), respectively. Whereas, the mean number of all variants and hotspot mutations per tumor samples only in GCs with MSS/MSI-L were 1 (0-5)/0.8 (0-1) and 0.5 (0-3)/0.8 (0-1), respectively.In conclusion, GC with MSI-H harbored more mutations in genes that act as a tumor suppressor or oncogene compared to GC with MSS/MSI-L. This finding suggests that the accumulation of MSIs contributes to the genetic diversity and complexities of GC. In addition, targeted NGS approach allows for detection of common and also rare clinically actionable mutations and profiles of comutations in multiple patients simultaneously. Because GC shows distinctive patterns related to ethnics, further studies pertaining to different racial/ethnic groups or cancer types may reinforce our investigations.

HSP90 inhibitor 17-DMAG exerts anticancer effects against gastric cancer cells principally by altering oxidant-antioxidant balance.

Heat shock protein 90 (HSP90) stabilizes numerous oncoproteins and, therefore, its inhibition has emerged as a promising antineoplastic strategy for diverse malignancies. In this study, we determined the therapeutic effects and mechanisms of action of a specific HSP90 inhibitor, 17-dimethylamino-ethylamino-17-demethoxygeldanamycin (17-DMAG), in gastric cancer cell lines (AGS, SNU-1, and KATO-III), patient-derived tissues, and a mouse xenograft model. 17-DMAG exerted anticancer effects against gastric cancer cells, manifested by significantly decreased proliferation rates (P < 0.05) and increased expression of apoptotic markers. Flow cytometry using dichlorofluorescein (DCF) diacetate revealed that 17-DMAG dose-dependently increases reactive oxygen species (ROS) levels in gastric cancer cells. Inhibition of ROS by N-acetyl-L-cysteine (NAC) abrogated the proapoptotic effects of 17-DMAG, as demonstrated by the decreased expression of proapoptotic proteins. In addition, 17-DMAG dose- and time-dependently reduced the expression of antioxidants such as catalase and glutathione peroxidase (GPx). Moreover, 17-DMAG reduced the expression of nuclear respiratory factor (NRF)-1 and NRF-2, and prevented them from migrating from the cytoplasm to the nucleus dose-dependently. Finally, in a nude mouse xenograft model, the shrinkage of tumors was more prominent in mice treated with 17-DMAG than in control mice (P < 0.05). Taken altogether, our results suggest that 17-DMAG exerts potent antineoplastic activity against gastric cancer cells primarily by promoting ROS generation and suppressing antioxidant enzyme activities.

The optimal duration of ischemic preconditioning for renal ischemia-reperfusion injury in mice.

PURPOSE: The aim of the present study was to investigate the protective effects of ischemic preconditioning for different periods of time and to elucidate the optimal safe ischemic preconditioning time for renal ischemia-reperfusion (I/R) injury in mice. METHODS: A total of 25 male C57BL/6 mice were randomly divided into 5 groups (sham, I/R, ischemic preconditioning [IP]-3, IP-5, and IP-7 groups), in which the kidney was preconditioned with IP of various durations and then subjected to I/R injury (the last 3 groups). To induce renal ischemia, the left renal pedicle was occluded with a nontraumatic microaneurysm clamp for 30 minutes followed by reperfusion for 24 hours. The effects of IP on renal I/R injury were evaluated in terms of renal function, tubular necrosis, apoptotic cell death and inflammatory cytokines. RESULTS: Results indicated that BUN and creatinine (Cr) levels increased significantly in the I/R group, but the elevations were significantly lower in IP groups, especially in the IP-5 group. Histological analysis revealed that kidney injury was markedly decreased in the IP-5 group compared with the I/R group, as evidenced by reduced renal necrosis/apoptosis. In addition, IP significantly inhibited gene expression of pro-inflammatory cytokines (TNF-α, IL-1ß, and IL-6) and chemokines (monocyte chemoattractant protein-1). Western blot analysis indicated that the expression levels of Toll-like receptor 4 (TLR4) and nuclear factor-kappa B (NF-κB) were upregulated in the I/R group, while expression was inhibited in the IP groups. CONCLUSION: Five-minute IP had the greatest protective effect against I/R injury.

Dysregulation of MicroRNA-196b-5p and MicroRNA-375 in Gastric Cancer.

PURPOSE: Dysregulated microRNAs (miRNAs) can contribute to cancer development by leading to abnormal proliferation of cells, apoptosis, and differentiation. Although several miRNAs that are related to gastric cancer have been identified, the reported results have been inconsistent. The aim of this study was to determine miRNA expression profiles and validate miRNAs up- and down-regulated in gastric cancer. MATERIALS AND METHODS: We evaluated 34 primary gastric cancer tissues and paired adjacent nontumorous gastric tissues. Total RNA was extracted, and low-molecular-weight RNAs (<200 nucleotides) were isolated for further analysis. Two pairs of tissues were processed for GeneChip microarray analysis, and the identified up- and down-regulated miRNAs were validated by real-time quantitative polymerase chain reaction (qPCR). RESULTS: In the set of differentially expressed miRNAs, 5 were overexpressed by more than 2 fold, and 5 were reduced by 2 fold or less in gastric cancer tissues compared with normal gastric tissues. Four of these miRNAs (miR-196b-5p, miR-375, miR-483-5p, and miR-486-5p) were then validated by qPCR, and the relative expression levels of 2 miRNAs (miR-196b-5p and miR-375) were significantly different between cancer and normal tissues. CONCLUSIONS: Our results revealed that the expression of miR-196b-5p and miR-375 significantly correlates with gastric cancer. These miRNAs could therefore serve as diagnostic biomarkers of gastric cancer.

Gastrointestinal stromal tumor solitary distant recurrence in the left brachialis muscle.

Gastrointestinal stromal tumors (GISTs) are mesenchymal tumors of the gastrointestinal tract that are most commonly found in the stomach. Although GISTs can spread to the liver and peritoneum, metastasis to the skeletal muscle is very rare and only four cases have previously been reported. These cases involved concurrent skeletal metastases of primary GISTs or liver metastases. Here, we report the first case of a distant recurrence in the brachialis muscle after complete remission of an extra-luminal gastric GIST following a wedge resection of the stomach, omental excision, and adjuvant imatinib therapy for one year. Ten months after therapy completion, the patient presented with swelling and tenderness in the left arm. Magnetic resonance imaging revealed a large mass in the brachialis muscle, which showed positivity for c-kit and CD34 upon pathologic examination. This is the first reported case of a solitary distant recurrence of a GIST in the muscle after complete remission had been achieved.