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Background: PET–CT-based patient metabolic profiling is a novel concept to incorporate patient-specific metabolism into gastric cancer care. Methods: Staging PET–CTs, demographics, and clinicopathologic variables of gastric cancer patients were obtained from a prospectively maintained institutional database. PET–CT avidity was measured in tumor, liver, spleen, four paired muscles, and two paired fat areas in each patient. The liver to rectus femoris (LRF) ratio was defined as the ratio of SUVmean of liver to the average SUVmean of the bilateral rectus femoris muscles. Kaplan–Meier and Cox-proportional hazards models were used to identify the impact of LRF ratio on OS. Results: Two hundred and one patients with distal gastroesophageal (48%) or gastric (52%) adenocarcinoma were included. Median age was 65 years, and 146 (73%) were male. On univariate analysis, rectus femoris PET–CT avidity and LRF ratio were significantly associated with overall survival (p < 0.05). LRF ratio was significantly higher in males, early-stage cancer, patients with an ECOG 0 or 1 performance status, patients with albumin > 3.5 mg/dL, and those with moderately differentiated tumor histology. In multivariable regression, gastric cancer stage, albumin, and LRF ratio were significant independent predictors of overall survival (LRF ratio HR = 0.73 (0.56–0.96); p = 0.024). Survival curves showed that the prognostic impact of LRF was associated with metastatic gastric cancer (p = 0.009). Conclusions: Elevated LRF ratio, a patient-specific PET–CT-based metabolic parameter, was independently associated with an improvement in OS in patients with metastatic gastric cancer. With prospective validation, LRF ratio may be a useful, host-specific metabolic parameter for prognostication in gastric cancer. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the efficacy of chemotherapy in patients with microsatellite instability (MSI)-high gastric cancer. Background: Although MSI-high gastric cancer is associated with a superior prognosis, recent studies question the benefit of perioperative chemotherapy in this population. Methods: Locally advanced gastric adenocarcinoma patients who either underwent surgery alone or also received neoadjuvant, perioperative, or adjuvant chemotherapy between 2000 and 2018 were eligible. MSI status, determined by next-generation sequencing or mismatch repair protein immunohistochemistry, was determined in 535 patients. Associations among MSI status, chemotherapy administration, overall survival (OS), disease-specific survival, and disease-free survival were assessed. Results: In 535 patients, 82 (15.3%) had an MSI-high tumor and ∼20% better OS, disease-specific survival, and disease-free survival. Grade 1 (90%–100%) pathological response to neoadjuvant chemotherapy was found in 0 of 40 (0%) MSI-high tumors versus 43 of 274 (16%) MSS. In the MSI-high group, the 3-year OS rate was 79% with chemotherapy versus 88% with surgery alone (P =0.48). In the MSS group, this was 61% versus 59%, respectively (P =0.96). After multivariable interaction analyses, patients with MSI-high tumors had superior survival compared with patients with MSS tumors whether given chemotherapy (hazard ratio=0.53, 95% confidence interval: 0.28–0.99) or treated with surgery alone (hazard ratio=0.15, 95% confidence interval: 0.02–1.17). Conclusions: MSI-high locally advanced gastric cancer was associated with superior survival compared with MSS overall, despite worse pathological chemotherapy response. In patients with MSI-high gastric cancer who received chemotherapy, the survival rate was ∼9% worse compared with surgery alone, but chemotherapy was not significantly associated with survival. [ABSTRACT FROM AUTHOR]

Objective: We sought to compare gastroesophageal junction (GEJ) cancer and gastric cancer (GC) and identify clinicopathological and oncological differences. Summary Background Data: GEJ cancer and GC are frequently studied together. Although the treatment approach for each often differs, clinico-pathological and oncological differences between the 2 have not been fully evaluated. Methods: We retrospectively identified patients with GEJ cancer or GC who underwent R0 resection at our center between January 2000 and December 2016. Clinicopathological characteristics, disease-specific survival (DSS), and site of first recurrence were compared. Results: In total, 2194 patients were analyzed: 1060 (48.3%) with GEJ cancer and 1134 (51.7%) with GC. Patients with GEJ cancer were younger (64 vs 66 years; P < 0.001), more often received neoadjuvant treatment (70.9% vs 30.2%; P < 0.001), and had lower pathological T and N status. Five-year DSS was 62.2% in patients with GEJ cancer and 74.6% in patients with GC (P < 0.001). After adjustment for clinicopathological factors, DSS remained worse in patients with GEJ cancer (hazard ratio, 1.78; 95% confidence interval, 1.40–2.26; P < 0.001). The cumulative incidence of recurrence was approximately 10% higher in patients with GEJ cancer (P < 0.001). The site of first recurrence was more likely to be hematogenous in patients with GEJ cancer (60.1% vs 31.4%; P < 0.001) and peritoneal in patients with GC (52.9% vs 12.5%; P < 0.001). Conclusions: GEJ adenocarcinoma is more aggressive, with a higher incidence of recurrence and worse DSS, compared with gastric adenocarcinoma. Distinct differences between GEJ cancer and GC, especially in patterns of recurrence, may affect evaluation of optimal treatment strategies. [ABSTRACT FROM AUTHOR]

Objective: The microbiome is hypothesized to have a significant impact on cancer development. In gastric cancer (GC), Helicobacter pylori is an established class I carcinogen. However, additional organisms in the intratumoral microbiome play an important role in GC pathogenesis and progression. In this study, we characterize the full spectrum of the microbes present within GC and identify distinctions among molecular subtypes. Methods: A microbiome bioinformatics pipeline that is generalizable across multiple next-generation sequencing platforms was developed. Microbial profiles for alpha diversity and enrichment were generated for 2 large, demographically distinct cohorts: (1) internal Memorial Sloan Kettering Cancer Center (MSKCC) and (2) The Cancer Genome Atlas (TCGA) cohorts. A total of 520 GC samples were compared with select tumor-adjacent nonmalignant samples. Microbiome differences among the GC molecular subtypes were identified. Results: Compared with nonmalignant samples, GC had significantly decreased microbial diversity in both MSKCC and TCGA cohorts (P <0.05). Helicobacter , Lactobacillus , Streptococcus , Prevotella , and Bacteroides were significantly more enriched in GC samples when compared with nonmalignant tissue (P <0.05). Microsatellite instability-high GC had distinct microbial enrichment compared with other GC molecular subtypes. Conclusion: Distinct patterns of microbial diversity and species enrichment were identified in patients with GC. Given the varied spectrum of disease progression and treatment response of GC, understanding unique microbial signatures will provide the landscape to explore key microbial targets for therapy. [ABSTRACT FROM AUTHOR]

Standard-of-care for resectable gastric/gastroesophageal junction cancer includes surgery and neoadjuvant-adjuvant 5-fluorouracil-leucovorin-oxaliplatin-docetaxel (FLOT) chemotherapy. Early-phase clinical studies support further clinical development of the immune checkpoint inhibitor (ICI); durvalumab, an anti-PD-L1 antibody, in patients with gastric/gastroesophageal junction cancer. Accumulating evidence indicates that ICIs combined with FLOT chemotherapy improve clinical outcomes in patients with advanced or metastatic cancer. We describe the rationale for and the design of MATTERHORN, a randomized, double-blind, placebo-controlled, phase III study investigating the efficacy and safety of neoadjuvant-adjuvant durvalumab and FLOT chemotherapy followed by adjuvant durvalumab monotherapy in patients with resectable gastric/gastroesophageal junction cancer. The planned sample size is 900 patients, the primary end point is event-free survival and safety and tolerability will be evaluated. Clinical trial registration: NCT04592913 (ClinicalTrials.gov). [ABSTRACT FROM AUTHOR]

Current guidelines recommend two-drug cytotoxic chemotherapy with a fluoropyrimidine (fluorouracil or capecitabine) and a platinum-based agent (oxaliplatin or cisplatin) as first-line treatment for advanced gastric cancer. Pembrolizumab monotherapy has demonstrated durable antitumor activity in patients with advanced programmed death ligand 1-positive (combined positive score ≥1) gastric/gastroesophageal junction adenocarcinoma. Accumulating evidence indicates that combining pembrolizumab with standard-of-care chemotherapy for the treatment of advanced or metastatic cancer improves clinical outcomes. We describe the rationale for and the design of the randomized, double-blind, placebo-controlled, Phase III KEYNOTE-859 study, which is investigating pembrolizumab in combination with chemotherapy as first-line treatment for patients with human epidermal growth factor receptor 2-negative advanced unresectable or metastatic gastric/gastroesophageal junction adenocarcinoma. The planned sample size is 1542 patients, and the primary end point is overall survival. Clinical trial registration: NCT03675737 (ClinicalTrials.gov). [ABSTRACT FROM AUTHOR]

Treatment options for patients with HER2-positive advanced gastric cancer are limited, and the prognosis for these patients is poor. Pembrolizumab has demonstrated promising antitumor activity in patients with advanced gastric or gastroesophageal junction adenocarcinoma as monotherapy, in combination with chemotherapy and in combination with trastuzumab. Combining pembrolizumab with trastuzumab and chemotherapy may therefore provide a benefit for patients with advanced HER2-positive gastric cancer. Here we aimed to describe the design of and rationale for the randomized, double-blind, placebo-controlled Phase III KEYNOTE-811 study, which will evaluate the efficacy and safety of pembrolizumab or placebo in combination with trastuzumab and chemotherapy as first-line treatment for patients with advanced HER2-positive gastric or gastroesophageal junction adenocarcinoma. Clinical trial registration: NCT03615326 (ClinicalTrials.gov). [ABSTRACT FROM AUTHOR]

Esophagogastric cancer (EGC) remains a major cause of cancer-related mortality. Overall survival in the metastatic setting remains poor, with few molecular targeted approaches having been successfully incorporated into routine care to-date: only first line anti-HER2 therapy in ERBB2-expressing tumors, second line anti-VEGFR2 therapy with ramucirumab in unselected patients, and pembrolizumab in PD-L1 expressing or MSI-H patients. EGFR inhibitors were extensively studied in EGC, including phase III trials with cetuximab (EXPAND), panitumumab (REAL3), and gefitinib (COG). All three trials were conducted in unselected populations, and therefore, failed to demonstrate clinical benefit. Here, we review previous attempts at targeting EGFR in EGC and potential future biomarkers for targeting this pathway in patients with EGFR -amplified tumors. [ABSTRACT FROM AUTHOR]

Objective: To determine whether changes in positron emission tomography (PET) avidity correlated with histologic response and were independently associated with outcome. Background: The implications of metabolic response to neoadjuvant therapy as measured by repeat PET imaging remain ill-defined for patients with gastric and gastroesophageal junction (GEJ) cancers. Methods: We identified patients with gastric and GEJ adenocarcinoma who were evaluated with PET imaging before and following neoadjuvant treatment, and subsequently underwent curative resections. Spearman rank correlation and Cox proportional hazards regression were used to evaluate standardized uptake value (SUV) and histologic response, pathologic parameters, and disease-specific survival (DSS). Results: From 2002 to 2013, 192 patients met our inclusion criteria. The median SUVmax response was 57.3% (range: -110% to 100%) for patients with GEJ cancers, with a corresponding median pathologic treatment response of 80% (range: 0% to 100%). The median SUVmax response was 32.5% (-230% to 100%) for patients with gastric cancers, with a corresponding median pathologic treatment response of 35% (range: 0% to 100%). The Spearman correlation between SUVmax response and histologic response was significant for patients with GEJ (rho = 0.19, P = 0.04) and gastric (rho = 0.44, P < 0.0001) cancers. For patients with GEJ ( P <0.0001 to 0.046) and gastric cancers ( P = 0.0003 to 0.016), histopathologic response and tumor staging predicted DSS. SUVmax response failed to demonstrate a relationship with DSS when entered into multivariable models containing conventional pathologic variables. Conclusion: Following completion of neoadjuvant therapy for gastric and GEJ adenocarcinoma, histopathologic staging remains the best predictor of outcome. Repeat post-treatment/preoperative PET imaging for the purpose of prognostication is of limited value. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to describe postoperative outcomes of total gastrectomy at our institution for patients with hereditary diffuse gastric cancer (HDGC). Background: HDGC, which is mainly caused by germline mutations in the E-cadherin gene (CDH1), renders a lifetime risk of gastric cancer of up to 70%, prompting a recommendation for prophylactic total gastrectomy. Methods: A prospective gastric cancer database identified 41 patients with CDH1 mutation who underwent total gastrectomy during 2005 to 2015. Perioperative, histopathologic, and long-term data were collected. Results: Of the 41 patients undergoing total gastrectomy, median age was 47 years (range 20 to 71). There were 14 men and 27 women, with 25 open operations and 16 minimally invasive operations. Median length of stay was 7 days (range 4 to 50). In total, 11 patients (27%) experienced a complication requiring intervention, and there was 1 peri-operative mortality (2.5%). Thirty-five patients (85%) demonstrated 1 or more foci of intramucosal signet ring cell gastric cancer in the examined specimen. At 16 months median follow-up, the median weight loss was 4.7 kg (15% of preoperative weight). By 6 to 12 months postoperatively, weight patterns stabilized. Overall outcome was reported to be “as expected” by 40% of patients and “better than expected” by 45%. Patient-reported outcomes were similar to those of other patients undergoing total gastrectomy. Conclusion: Total gastrectomy should be considered for all CDH1 mutation carriers because of the high risk of invasive diffuse-type gastric cancer and lack of reliable surveillance options. Although most patients have durable weight loss after total gastrectomy, weights stabilize at about 6 to 12 months postoperatively, and patients report outcomes as being good to better than their preoperative expectations. No patients have developed gastric cancer recurrence after resections. [ABSTRACT FROM AUTHOR]

This is a summary of the 1-year results of a clinical research study known as CheckMate 649 published in The Lancet in June 2021. The 2-year results on the participants' health and overall quality of life from the same study are in a second publication in Nature in March 2022. Until recently, chemotherapy was the only first treatment option for people with advanced or metastatic gastroesophageal adenocarcinoma who had not been treated before. Patients receiving chemotherapy lived on average for less than 1 year. Nivolumab is an immunotherapy that works by activating a person's immune system to fight back against cancer cells. The goal of CheckMate 649 was to find out if the combination of nivolumab and chemotherapy would help patients with advanced or metastatic gastroesophageal adenocarcinoma live longer and without their cancer getting worse. Results from the final analysis are reported here. Of 1581 people who took part in the study, 789 received nivolumab and chemotherapy and 792 received chemotherapy. Researchers found that, on average, participants who received nivolumab and chemotherapy lived longer overall than those who received chemotherapy alone. The length of time participants lived without their cancer getting worse was also longer on average with nivolumab and chemotherapy than chemotherapy treatment alone. However, more participants in the nivolumab and chemotherapy group had side effects than those in the chemotherapy group. The three most common side effects in both types of treatment were nausea (urge to vomit), diarrhea and peripheral neuropathy. Participants who received nivolumab and chemotherapy had a lower risk of their cancer symptoms worsening and reported that they were 'less bothered' from side effects of treatment than those receiving chemotherapy alone. The nivolumab and chemotherapy combination is considered a new standard treatment option and is approved in several countries as a treatment for adults who have not been treated before for their advanced or metastatic gastroesophageal cancer based on results from CheckMate 649. Clinical Trial Registration: NCT02872116 (ClinicalTrials.gov) [ABSTRACT FROM AUTHOR]

In this article, we review the literature on the current advances in targeted therapies for metastatic gastric cancer aimed at improving patient care. We conclude that the key to guiding targeted therapy is individual biomarkers, which are not completely elucidated. HER2 overexpression is the only predictive biomarker currently in use. Furthermore, it is necessary to understand that gastric tumors are heterogeneous; therefore, is impossible to evaluate a novel biological compound without evaluating personal biomarkers. The selection of patients who are able to receive each treatment is paramount for improving advanced gastric cancer survival and reducing unnecessary costs. [ABSTRACT FROM AUTHOR]