Development and validation of a prognostic and predictive 32-gene signature for gastric cancer.

Genomic profiling can provide prognostic and predictive information to guide clinical care. Biomarkers that reliably predict patient response to chemotherapy and immune checkpoint inhibition in gastric cancer are lacking. In this retrospective analysis, we use our machine learning algorithm NTriPath to identify a gastric-cancer specific 32-gene signature. Using unsupervised clustering on expression levels of these 32 genes in tumors from 567 patients, we identify four molecular subtypes that are prognostic for survival. We then built a support vector machine with linear kernel to generate a risk score that is prognostic for five-year overall survival and validate the risk score using three independent datasets. We also find that the molecular subtypes predict response to adjuvant 5-fluorouracil and platinum therapy after gastrectomy and to immune checkpoint inhibitors in patients with metastatic or recurrent disease. In sum, we show that the 32-gene signature is a promising prognostic and predictive biomarker to guide the clinical care of gastric cancer patients and should be validated using large patient cohorts in a prospective manner.

Complementary utility of targeted next-generation sequencing and immunohistochemistry panels as a screening platform to select targeted therapy for advanced gastric cancer.

We tested the clinical utility of combined profiling of Ion Torrent PGM based next-generation sequencing (NGS) and immunohistochemistry (IHC) for assignment to molecularly targeted therapies. A consecutive cohort of 93 patients with advanced/metastatic GC who underwent palliative chemotherapy between March and December 2015 were prospectively enrolled. Formalin fixed paraffin embedded tumor biopsy specimens were subjected to a 10 GC panels [Epstein Barr virus encoding RNA in-situ hybridization, IHC for mismatch repair proteins (MMR; MLH1, PMS2, MSH2, and MSH6), receptor tyrosine kinases (HER2, EGFR, and MET), PTEN, and p53 protein], and a commercial targeted NGS panel of 52 genes (Oncomine Focus Assay). Treatment was based on availability of targeted agents at the time of molecular diagnosis. Among the 81 cases with available tumor samples, complete NGS and IHC profiles were successfully achieved in 66 cases (81.5%); only IHC results were available for 15 cases. Eight cases received matched therapy based on sequencing results; ERBB2 amplification, trastuzumab (n = 4); PIK3CA mutation, Akt inhibitor (n = 2); and FGFR2 amplification, FGFR2b inhibitor (n = 2). Eleven cases received matched therapy based on IHC; ERBB2 positivity, trastuzumab (n = 5); PTEN loss (n = 2), PI3Kß inhibitor; MMR deficiency (n = 2), PD-1 inhibitor; and EGFR positivity (n = 2), pan-ERBB inhibitor. A total of 19 (23.5%) and 62 (76.5%) cases were treated with matched and non-matched therapy, respectively. Matched therapy had significantly higher overall response rate than non-matched therapy (55.6% vs 13.1%, P = 0.001). NGS and IHC markers provide complementary utility in identifying patients who may benefit from targeted therapies.

Lymphadenectomy with Optimum of 29 Lymph Nodes Retrieved Associated with Improved Survival in Advanced Gastric Cancer: A 25,000-Patient International Database Study.

BACKGROUND: Gastric adenocarcinoma is an aggressive disease with frequent lymph node (LN) metastases for which lymphadenectomy results in a survival benefit. In the US, the National Comprehensive Cancer Network guidelines recommend D2 lymphadenectomy or a minimum of 15 LNs retrieved. However, retrieval of only 15 LNs is considered by most international guidelines as inadequate. We sought to evaluate the survival benefits associated with a more complete lymphadenectomy. STUDY DESIGN: An international database was constructed by combining gastric cancer cases from the Surveillance, Epidemiology, and End Results program database (n = 13,932) and the Yonsei University Gastric Cancer database (n = 11,358) (total n = 25,289). Kaplan-Meier survival analysis was performed along with Joinpoint analysis to obtain the optimal number of LNs to retrieve based on survival. Prognostic significance of number of nodes retrieved was then confirmed with univariate and multivariate analyses. RESULTS: Analysis for both mean and median survival yielded 29 LNs removed as the Joinpoint. This was confirmed with multivariate analysis, where 15 retrieved LNs cutoff fell out of the model and 29 retrieved LNs remained intact, with a hazard ratio of 0.799 (95% CI 0.759 to 0.842; p < 0.001). Stage-stratified Kaplan-Meier analysis for a cutoff point of 29 LNs also demonstrated a statistically significant improvement in survival. CONCLUSIONS: Joinpoint analysis has allowed for the creation of a model demonstrating the point at which additional dissection would not provide additional benefit. This large international dataset analysis demonstrates that the maximal survival advantage is seen by performing a lymphadenectomy with a minimum of 29 LNs retrieved.

The Korean Gastric Cancer Cohort Study: Study Protocol and Brief Results of a Large-Scale Prospective Cohort Study.

PURPOSE: This study aimed to establish a large-scale database of patients with gastric cancer to facilitate the development of a national-cancer management system and a comprehensive cancer control policy. MATERIALS AND METHODS: An observational prospective cohort study on gastric cancer was initiated in 2010. A total of 14 cancer centers throughout the country and 152 researchers were involved in this study. Patient enrollment began in January 2011, and data regarding clinicopathological characteristics, life style-related factors, quality of life, as well as diet diaries were collected. RESULTS: In total, 4,963 patients were enrolled until December 2014, and approximately 5% of all Korean patients with gastric cancer annually were included. The mean age was 58.2±11.5 years, and 68.2% were men. The number of patients in each stage was as follows: 3,394 patients (68.4%) were in stage IA/B; 514 patients (10.4%), in stage IIA/B; 469 patients (9.5%), in stage IIIA/B/C; and 127 patients (2.6%), in stage IV. Surgical treatment was performed in 3,958 patients (79.8%), endoscopic resection was performed in 700 patients (14.1%), and 167 patients (3.4%) received palliative chemotherapy. The response rate for the questionnaire on the quality of life was 95%; however, diet diaries were only collected for 27% of patients. CONCLUSIONS: To provide comprehensive information on gastric cancer for patients, physicians, and government officials, a large-scale database of Korean patients with gastric cancer was established. Based on the findings of this cohort study, an effective cancer management system and national cancer control policy could be developed.

Prognostic significance and frequency of EGFR expression and amplification in surgically resected advanced gastric cancer.

OBJECTIVE: The aim of this study is to find the frequency and the role of epidermal growth factor receptor expression as a prognostic biomarker in gastric cancer. METHODS: We evaluated the prognostic value and frequency of epidermal growth factor receptor expression and amplification using immunohistochemistry and silver in situ hybridization in a large cohort of curatively resected gastric cancer. RESULTS: Of the total of 935 cases, 294 (31.4%), 101 (10.8%) and 36 (3.9%) patients showed epidermal growth factor receptor 1+, 2+ and 3+ expression on immunohistochemistry, respectively. Epidermal growth factor receptor-positive (2+/3+) patients more frequently had intestinal type than epidermal growth factor receptor-negative (0/1+) patients (82.5 vs. 44.1%, P < 0.001). After adjusting for sex, age, stage and adjuvant chemotherapy, epidermal growth factor receptor-positive patients had a favorable overall survival outcome compared with epidermal growth factor receptor-negative patients (hazard ratio, 0.734; 95% confidence interval, 0.541-0.997; P = 0.047), especially in Stage III disease (hazard ratio, 0.676; 95% confidence interval, 0.472-0.968; P = 0.033). Among the 393 cases available for  in situ hybridization, the correlation between immunohistochemistry and in situ hybridization was statistically significant (P = 0.001). Thirteen patients with gene amplification (3.3%) did not show different survival outcome with others (P = 0.359). CONCLUSION: Epidermal growth factor receptor positivity was an independent favorable prognostic factor for gastric cancer, especially in Stage III disease.

Adjuvant capecitabine plus oxaliplatin for gastric cancer after D2 gastrectomy (CLASSIC): 5-year follow-up of an open-label, randomised phase 3 trial.

BACKGROUND: The CLASSIC trial was done to compare adjuvant capecitabine plus oxaliplatin versus observation after D2 gastrectomy for patients with stage II or III gastric cancer. The planned interim analysis of CLASSIC (median follow-up 34 months) showed that adjuvant capecitabine plus oxaliplatin significantly improved disease-free survival, the primary endpoint, compared with observation after D2 gastrectomy. We report the 5-year follow-up data from the trial. METHODS: CLASSIC was a phase 3, randomised, open-label study done at 35 cancer centres, medical centres, and hospitals in China, South Korea, and Taiwan. Patients with stage II-IIIB gastric cancer who underwent curative D2 gastrectomy were randomly assigned (1:1) after surgery to receive adjuvant chemotherapy with capecitabine and oxaliplatin (eight 3-week cycles of oral capecitabine 1000 mg/m(2) twice daily on days 1-14 plus intravenous oxaliplatin 130 mg/m(2) on day 1) for 6 months or observation alone. Randomisation was stratified by country and disease stage with a permuted block (size four) design. Neither patients nor investigators were masked to treatment assignment. The primary outcome was 3-year disease-free survival in the intention-to-treat population. This analysis presents the final preplanned assessment of outcomes after 5 years. The study is registered with ClinicalTrials.gov, NCT00411229. FINDINGS: We enrolled 1035 patients: 520 were randomly assigned to adjuvant capecitabine and oxaliplatin, and 515 to observation. Median follow-up for this analysis in the intention-to-treat population was 62·4 months (IQR 54-70). 139 (27%) patients had disease-free survival events in the adjuvant capecitabine and oxaliplatin group versus 203 (39%) patients in the observation group (stratified hazard ratio [HR] 0·58, 95% CI 0·47-0·72; p<0·0001). Estimated 5-year disease-free survival was 68% (95% CI 63-73) in the adjuvant capecitabine and oxaliplatin group versus 53% (47-58) in the observation alone group. By the clinical cutoff date, 103 patients (20%) had died in the adjuvant capecitabine and oxaliplatin group versus 141 patients (27%) in the observation group (stratified HR 0·66, 95% CI 0·51-0·85; p=0·0015). Estimated 5-year overall survival was 78% (95% CI 74-82) in the adjuvant capecitabine and oxaliplatin group versus 69% (64-73) in the observation group. Adverse event data were not collected after the primary analysis. INTERPRETATION: Adjuvant treatment with capecitabine plus oxaliplatin after D2 gastrectomy should be considered for patients with operable stage II or III gastric cancer. FUNDING: F Hoffmann La-Roche and Sanofi.

Method of reconstruction governs iron metabolism after gastrectomy for patients with gastric cancer.

OBJECTIVE: Anemia after gastrectomy is commonly neglected by clinicians despite being an important and frequent long-term metabolic sequela. We hypothesized that the incidence and timing of the occurrence of iron deficiency after gastrectomy is closely associated with the extent of gastrectomy and the reconstruction method, and we investigated the treatment outcomes of iron supplementation to understand iron metabolism and determine the optimal reconstruction method after gastrectomy. PATIENTS AND METHODS: Using a prospective gastric cancer database, we identified 381 patients with early gastric cancer with complete hematologic parameters who underwent gastrectomy between January 2004 and May 2008. Kaplan-Meier methods, Cox regression, and logistic regression were used to evaluate the associations of the extent of gastrectomy and reconstruction method with iron metabolism. RESULTS: The prevalence of iron deficiency 3 years after gastrectomy was 69.1%, and iron-deficiency anemia was observed in 31.0% of patients. Iron deficiency developed in 64.8% and 90.5% of patients after distal gastrectomy and total gastrectomy within 3 years after surgery (P < 0.0001), respectively. Iron deficiency was significantly more frequent in women than in men (P < 0.0001) and after gastrojejunostomy than after gastroduodenostomy (P < 0.0001). Serum ferritin levels were different according to the extent of gastrectomy and reconstruction method. The proportion of patients treated for iron-deficiency anemia was also significantly different according to the extent of gastrectomy (P = 0.020). CONCLUSIONS: Iron deficiency occurs in most patients with gastric cancer after gastrectomy, and its incidence was different according to the extent of gastrectomy and reconstruction method. To improve iron metabolism after distal gastrectomy, gastroduodenostomy would be the method of reconstruction whenever possible.

Adjuvant capecitabine and oxaliplatin for gastric cancer after D2 gastrectomy (CLASSIC): a phase 3 open-label, randomised controlled trial.

BACKGROUND: D2 gastrectomy is recommended in US and European guidelines, and is preferred in east Asia, for patients with resectable gastric cancer. Adjuvant chemotherapy improves patient outcomes after surgery, but the benefits after a D2 resection have not been extensively investigated in large-scale trials. We investigated the effect on disease-free survival of adjuvant chemotherapy with capecitabine plus oxaliplatin after D2 gastrectomy compared with D2 gastrectomy only in patients with stage II-IIIB gastric cancer. METHODS: The capecitabine and oxaliplatin adjuvant study in stomach cancer (CLASSIC) study was an open-label, parallel-group, phase 3, randomised controlled trial undertaken in 37 centres in South Korea, China, and Taiwan. Patients with stage II-IIIB gastric cancer who had had curative D2 gastrectomy were randomly assigned to receive adjuvant chemotherapy of eight 3-week cycles of oral capecitabine (1000 mg/m(2) twice daily on days 1 to 14 of each cycle) plus intravenous oxaliplatin (130 mg/m(2) on day 1 of each cycle) for 6 months or surgery only. Block randomisation was done by a central interactive computerised system, stratified by country and disease stage. Patients, and investigators giving interventions, assessing outcomes, and analysing data were not masked. The primary endpoint was 3 year disease-free survival, analysed by intention to treat. This study reports a prespecified interim efficacy analysis, after which the trial was stopped after a recommendation by the data monitoring committee. The trial is registered at ClinicalTrials.gov (NCT00411229). FINDINGS: 1035 patients were randomised (520 to receive chemotherapy and surgery, 515 surgery only). Median follow-up was 34·2 months (25·4-41·7) in the chemotherapy and surgery group and 34·3 months (25·6-41·9) in the surgery only group. 3 year disease-free survival was 74% (95% CI 69-79) in the chemotherapy and surgery group and 59% (53-64) in the surgery only group (hazard ratio 0·56, 95% CI 0·44-0·72; p<0·0001). Grade 3 or 4 adverse events were reported in 279 of 496 patients (56%) in the chemotherapy and surgery group and in 30 of 478 patients (6%) in the surgery only group. The most common adverse events in the intervention group were nausea (n=326), neutropenia (n=300), and decreased appetite (n=294). INTERPRETATION: Adjuvant capecitabine plus oxaliplatin treatment after curative D2 gastrectomy should be considered as a treatment option for patients with operable gastric cancer. FUNDING: F Hoffmann-La Roche and Sanofi-Aventis.

A pilot study of S-1 plus cisplatin versus 5-fluorouracil plus cisplatin for postoperative chemotherapy in histological stage IIIB-IV (M0) gastric cancer.

BACKGROUND: Although its efficacy is unproven, 5-fluorouracil plus cisplatin (FP) is used to prevent postoperative relapse in gastric cancer. We investigated the safety and feasibility of S-1 plus cisplatin (SP) vs. FP for stage IIIB-IV (M0) gastric cancer. METHODS: Following curative resection, 41 stage IIIB-IV (M0) gastric cancer patients were assigned to SP (eight 14-day cycles of S-1 [40 mg/m(2) twice daily] plus cisplatin [60 mg/m(2) day 1] administered every 3 weeks) or FP (six 3-day cycles of FU [1 g/m(2) per day] plus cisplatin [80 mg/m(2) day 1] every 4 weeks). Doses were reduced based on predefined criteria. RESULTS: Patient characteristics were balanced between the two arms. In total, 124 cycles of SP (N = 20, median = 7, range 1-8) and 113 cycles of FP (N = 21, median 6, range 1-6) were administered. The median relative dose intensity per patient was 75% (49.99-100%) for S-1, 100% (75-100%) for cisplatin in SP, and 100% (64-100%) for 5-FU, 100% (60-100%) for cisplatin in FP. The relative dose intensity of FP was stable, while that of SP decreased during treatment. After median follow-up of 7.9 months (3.8-14.55), the median RFS was not reached. Relapse occurred in two (10%) patients on SP and five (23.8%) in the FP arm (P = 0.24). The incidence of grade 3-4 granulocytopenia was 36.8% with SP and 14.3% with FP. Grade 3-4 non-hematologic toxicities included fatigue (5.2% with SP vs. 4.8% with FP), vomiting (10.5% with SP vs. 0% with FP), and infection (5.2% with SP vs. 0% FP). CONCLUSION: S-1 plus cisplatin was feasible and tolerable as adjuvant treatment for stage IIIB-IV (M0) gastric cancer. However, because of decreased relative dose intensity during treatment, further study is warranted to determine optimal dosage and combination.

Microsatellite instability in sporadic gastric cancer: its prognostic role and guidance for 5-FU based chemotherapy after R0 resection.

This study investigated whether MSI status can be used as a prognostic biomarker and whether it is helpful for predicting which patients will benefit from 5-FU based adjuvant chemotherapy. Between 2005 and 2008, an MSI status examination was performed in 1,990 gastric cancer patients who had undergone curative gastrectomy for gastric adenocarcinoma. MSI was analyzed by PCR amplification with fluorescent dye-labeled primers of mononucleotide markers (BAT25 and BAT26) and dinucleotide markers (D5S346, D2S123 and D17S250) specific to the microsatellite loci. Patients with MSI-H tumors accounted for 8.5% (n = 170) of the total study population. They tended to be older and female and to have distal tumor location, lower tumor stage, intestinal type of Lauren classification and differentiated histological type. The disease-free survival curves showed no significant differences between MSS/MSI-L and MSI-H patients at each stage of I, II, III and IV. In gastric cancer patients with stage II and III, 5-FU-based adjuvant chemotherapy showed better disease-free survival in the MSS/MSI-L group, but showed no benefits in the MSI-H group. By multivariate analysis, patients with MSS/MSI-L tumors benefited from 5-FU-based adjuvant chemotherapy in terms of tumor disease-free survival. MSI status in gastric cancer is not itself a prognostic indicator. However, it appears to be a possible guidance for the use of 5-FU-based chemotherapy in stage II and III gastric cancers after R0 resection.

Advanced detection of recent changing trends in gastric cancer survival: up-to-date comparison by period analysis.

OBJECTIVE: To establish a comprehensive cancer treatment and prevention policy, data collection should be performed in a timely manner, and survival analysis needs to reflect changes in treatment strategy. Therefore, we introduced the concept of period analysis for gastric cancer, the most prevalent cancer in Korea. We estimated 5- and 10-year survival trend of gastric cancer, based on data from the Yonsei Cancer Center Tumor Registry between 1990 and 2004. METHODS: We compared the differences in survival between cohort, complete and period analyses for two different periods, 1995-99 and 2000-04. RESULTS: A total of 11 724 cases were included. The median age of cancer diagnosis gradually increased over time, and more patients were diagnosed with Stage I disease in recent years. In the basic comparison of three estimated analytic methods (cohort, complete and period), period analysis (45.8%) was most similar to the actual 5-year observed survival rate (48.5%), when compared with cohort (43.6%) and complete (44.8%) analyses. When we compared survival between different 10-year periods (1990-99 and 1995-2004), period analysis demonstrated a greater difference than complete analysis (9.0 versus 3.9%). Subgroup analysis indicated that the survival improvement was determined by period analysis, and it was more pronounced for the age group <74 years and in Stages III-IV patients. CONCLUSIONS: We observed that period analysis demonstrates the most similar results to the actual observed survival and is, therefore, a useful method to derive precise cancer survival in gastric cancer. This information is useful to understand survival differences that are influenced by changing treatment strategy.

Intrinsic subtypes of gastric cancer, based on gene expression pattern, predict survival and respond differently to chemotherapy.

BACKGROUND & AIMS: Gastric cancer (GC) is a heterogeneous disease comprising multiple subtypes that have distinct biological properties and effects in patients. We sought to identify new, intrinsic subtypes of GC by gene expression analysis of a large panel of GC cell lines. We tested if these subtypes might be associated with differences in patient survival times and responses to various standard-of-care cytotoxic drugs. METHODS: We analyzed gene expression profiles for 37 GC cell lines to identify intrinsic GC subtypes. These subtypes were validated in primary tumors from 521 patients in 4 independent cohorts, where the subtypes were determined by either expression profiling or subtype-specific immunohistochemical markers (LGALS4, CDH17). In vitro sensitivity to 3 chemotherapy drugs (5-fluorouracil, cisplatin, oxaliplatin) was also assessed. RESULTS: Unsupervised cell line analysis identified 2 major intrinsic genomic subtypes (G-INT and G-DIF) that had distinct patterns of gene expression. The intrinsic subtypes, but not subtypes based on Lauren's histopathologic classification, were prognostic of survival, based on univariate and multivariate analysis in multiple patient cohorts. The G-INT cell lines were significantly more sensitive to 5-fluorouracil and oxaliplatin, but more resistant to cisplatin, than the G-DIF cell lines. In patients, intrinsic subtypes were associated with survival time following adjuvant, 5-fluorouracil-based therapy. CONCLUSIONS: Intrinsic subtypes of GC, based on distinct patterns of expression, are associated with patient survival and response to chemotherapy. Classification of GC based on intrinsic subtypes might be used to determine prognosis and customize therapy.

Robotic gastrectomy as an oncologically sound alternative to laparoscopic resections for the treatment of early-stage gastric cancers.

OBJECTIVE: To evaluate the comparative safety and efficacy of robotic vs laparoscopic gastrectomy for early-stage gastric cancer. DESIGN: Retrospective analysis. SETTING: Tertiary hospital. PATIENTS: Eight hundred twenty-seven patients with gastric cancer. INTERVENTIONS: Between July 2005 and April 2009, 827 patients with gastric cancer underwent 236 robotic and 591 laparoscopic radical gastrectomies with curative intent. The patients' data were prospectively collected and retrospectively analyzed. MAIN OUTCOME MEASURES: We performed a comparative analysis between the robotic surgery group and laparoscopic surgery group for preoperative patient characteristics, intraoperative factors, and postoperative morbidity and mortality. RESULTS: The robotic group was younger than the laparoscopic group, but other preoperative patient characteristics did not differ. The mean operative time for the robotic group (219.5 minutes) was on average 49 minutes longer than the laparoscopic group (170.7 minutes) (P < .001), while mean blood loss was significantly less in the robotic group (91.6 mL vs 147.9 mL; P = .002). The robotic group had mortality of 0.4% and morbidity of 11.0%, comparable with those of the laparoscopic group (P > .05). The number of lymph nodes retrieved per level was adequate in both groups and did not differ significantly. Robotic D1+α (n = 5), D1+ß (n = 126), and D2 (n = 105) dissections retrieved 27.2, 36.7, and 42.4 mean numbers of lymph nodes, respectively. Except for 3 cases in the laparoscopic group, all specimens had negative margins. CONCLUSIONS: Our largest comparative study demonstrates robotic gastrectomy to have better short-term and comparable oncologic outcomes compared with laparoscopic gastrectomy. A robotic approach to gastric cancer is a promising alternative to laparoscopic surgery.

Changing patterns of prognosticators during 15-year follow-up of advanced gastric cancer after radical gastrectomy and adjuvant chemotherapy: a 15-year follow-up study at a single korean institute.

BACKGROUND: We evaluated the long-term natural history of gastric cancer after radical gastrectomy and adjuvant chemotherapy through a 15-year follow-up study at a single institute. METHODS: Five hundred patients with advanced gastric adenocarcinoma who received radical gastrectomy and adjuvant chemotherapy were included in this long-term follow-up study. Patients were evaluated by imaging studies and upper gastrointestinal series or endoscopy every 6 months until the 10th year after surgery. Since then, the patients have been followed yearly in the same manner. RESULTS: The median follow-up period was 190.5 months. The recurrence rate in 5-year survivors was 10.8%. The dominant recurrence pattern was peritoneal carcinomatosis within 5 years and distant metastasis after 5 years post gastrectomy. Tumor stage was a clear-cut prognosticator within 5 years post gastrectomy, but was no longer informative in 5-10 years. At this period, only stage IV (IB-IIIB vs IVM0) was a significantly poor prognosticator. After 10 years, second primary cancer (seven cases) became as important an issue as recurrence of primary gastric cancer (six cases). CONCLUSIONS: In patients with gastric carcinoma treated with radical gastrectomy and adjuvant chemotherapy, late recurrence after 5 years post gastrectomy was not rare. Prognosticators were varied depending on the length of time after surgery. Tumor factors including stage were prognosticators within 5 years post gastrectomy, but tumor factors except stage IV had no prognostic value after 5 years. In the 5-10 years post gastrectomy, only stage IV (IB-IIIB vs IVM0) was a poor prognosticator. Also, after 10 years, there were no prognosticators.