Effect of preoperative chemotherapy on the histopathological classification of gastric cancer.

BACKGROUND: In the era of individualized gastric cancer (GC) treatment, accurate determination of histological subtype becomes increasingly relevant. As yet, it is unclear whether preoperative chemotherapy may affect the histological subtype. The aim of this study was to assess concordance in histological subtype between pretreatment biopsies and surgical resection specimens before and after the introduction of perioperative treatment. METHODS: Histological subtype was centrally determined in paired GC biopsies and surgical resection specimens of patients treated with either surgery alone (SA) in the Dutch D1/D2 study or with preoperative chemotherapy (CT) in the CRITICS trial. The histological subtype as determined in the resection specimen was considered the gold standard. Concordance rates and sensitivity and specificity of intestinal, diffuse, mixed, and "other" subtypes of GC were analyzed. RESULTS: In total, 105 and 515 pairs of GC biopsies and resection specimens of patients treated in the SA and CT cohorts, respectively, were included. Overall concordance in the histological subtype was 72% in the SA and 74% in the CT cohort and substantially higher in the diffuse subtype (83% and 86%) compared to the intestinal (70% and 74%), mixed (21% and 33%) and "other" subtypes (54% and 54%). In the SA cohort, sensitivities and specificities were 0.88 and 0.71 in the intestinal, 0.67 and 0.93 in the diffuse, 0.20 and 0.98 in the mixed, and 0.50 and 0.93 in the "other" subtypes, respectively. CONCLUSION: Our results suggest that accurate determination of histological subtype on gastric cancer biopsies is suboptimal but that the impact of preoperative chemotherapy on histological subtype is negligible.

Adjuvant chemotherapy for resected duodenal adenocarcinoma: a case-matched analysis in nation wide cohort.

BACKGROUND: Duodenal adenocarcinoma (DA) is a rare tumor for which survival data on adjuvant chemotherapy in patients after surgical treatment are unclear. This case-matched study in a nationwide cohort aims to investigate the benefit of adjuvant chemotherapy for patients with resectable DA on overall survival. METHODS: All patients diagnosed with DA and intestinal type periampullary adenocarcinoma (PVA) in the Netherlands between 2000 and 2015 were included (n = 1316). Patients with disease stages II and III who underwent resection and adjuvant chemotherapy were matched (1:2), based on identified covariates associated with OS, with patients who underwent surgery alone. Overall survival was compared using Kaplan-Meier estimates. RESULTS: The median OS was 49.9 months in patients who underwent curative resection (n = 649). Univariate and multivariate analysis showed a significant influence of age, lymph node involvement, and T- stage on survival. The group of patients receiving adjuvant treatment consisted of 43 patients and the non-adjuvant group of 83 case-matched patients. The median OS of the complete matched cohort (n = 126) was 26.9 months. No statistically significant survival benefit was found for the adjuvant group as compared to the group treated with surgery alone (median OS = 34.4 months and 23.0 months, p = 0.20). CONCLUSION: This population-based, case-matched analysis demonstrates no statistically significant survival benefit for adjuvant chemotherapy after curative resection in stages II and III patients. Future studies with specified treatment regimens as well as thorough stratification for prognostic factors will be required in order to more definitively determine the role of adjuvant therapy.

Pre-treatment tumor-infiltrating T cells influence response to neoadjuvant chemoradiotherapy in esophageal adenocarcinoma.

Esophageal adenocarcinoma (EAC) is a disease with dismal treatment outcomes. Response to neoadjuvant chemoradiation (CRT) varies greatly. Although the underlying mechanisms of CRT resistance are not identified, accumulating evidence indicates an important role for local antitumor immunity. To explore the immune microenvironment in relation to response to CRT we performed an in-depth analysis using multiplex immunohistochemistry, flow cytometry and mRNA expression analysis (NanoString) to generate a detailed map of the immunological landscape of pretreatment biopsies as well as peripheral blood mononuclear cells (PBMCs) of EAC patients. Response to CRT was assessed by Mandard's tumor regression grade (TRG), disease-free- and overall survival. Tumors with a complete pathological response (TRG 1) to neoadjuvant CRT had significantly higher tumor-infiltrating T cell levels compared to all other response groups (TRG 2-5). These T cells were also in closer proximity to tumor cells in complete responders compared to other response groups. Notably, immune profiles of near-complete responders (TRG 2) showed more resemblance to non-responders (TRG 3-5) than to complete responders. A high CD8:CD163 ratio in the tumor was associated with an improved disease-free survival. Gene expression analyses revealed that T cells in non-responders were Th2-skewed, while complete responders were enriched in cytotoxic immune cells. Finally, complete responders were enriched in circulating memory T cells. preexisting immune activation enhances the chance for a complete pathological response to neoadjuvant CRT. This information can potentially be used for future patient selection, but also fuels the development of immunomodulatory strategies to enhance CRT efficacy.

Adjuvant chemotherapy is superior to chemoradiation after D2 surgery for gastric cancer in the per-protocol analysis of the randomized CRITICS trial.

BACKGROUND: The Intergroup 0116 and the MAGIC trials changed clinical practice for resectable gastric cancer in the Western world. In these trials, overall survival improved with post-operative chemoradiotherapy (CRT) and perioperative chemotherapy (CT). Intention-to-treat analysis in the CRITICS trial of post-operative CT or post-operative CRT did not show a survival difference. The current study reports on the per-protocol (PP) analysis of the CRITICS trial. PATIENTS AND METHODS: The CRITICS trial was a randomized, controlled trial in which 788 patients with stage Ib-Iva resectable gastric or esophagogastric adenocarcinoma were included. Before start of preoperative CT, patients from the Netherlands, Sweden and Denmark were randomly assigned to receive post-operative CT or CRT. For the current analysis, only patients who started their allocated post-operative treatment were included. Since it is uncertain that the two treatment arms are balanced in such PP analysis, adjusted proportional hazards regression analysis and inverse probability weighted analysis were used to minimize the risk of selection bias and to estimate and compare overall and event-free survival. RESULTS: Of the 788 patients, 478 started post-operative treatment according to protocol, 233 (59%) patients in the CT group and 245 (62%) patients in the CRT group. Patient and tumor characteristics between the groups before start of the post-operative treatment were not different. After a median follow-up of 6.7 years since the start of post-operative treatment, the 5-year overall survival was 57.9% (95% confidence interval: 51.4% to 64.3%) in the CT group versus 45.5% (95% confidence interval: 39.2% to 51.8%) in the CRT group (adjusted hazard ratio CRT versus CT: 1.62 (1.24-2.12), P = 0.0004). Inverse probability weighted analysis resulted in similar hazard ratios. CONCLUSION: After adjustment for all known confounding factors, the PP analysis of patients who started the allocated post-operative treatment in the CRITICS trial showed that the CT group had a significantly better 5-year overall survival than the CRT group (NCT00407186).

Correction to: [89Zr]Zr-cetuximab PET/CT as biomarker for cetuximab monotherapy in patients with RAS wild-type advanced colorectal cancer.

Missing Electronic Supplementary Materials.

MSI as a predictive factor for treatment outcome of gastroesophageal adenocarcinoma.

Gastroesophageal cancers are a major cause of death worldwide and treatment outcomes remain poor. Adequate predictive biomarkers have not been identified. Microsatellite instability (MSI) as a result of mismatch repair deficiency is present in four to twenty percent of gastroesophageal cancers and has been associated with favorable survival outcomes compared to microsatellite stable tumors. This prognostic advantage may be related to immunosurveillance, which may also explain the favorable response to immune checkpoint inhibition observed in MSI high (MSI-H) tumors. The value of conventional cytotoxic treatment in MSI-H tumors is unclear and results on its efficacy range from detrimental to beneficial effects. Here the recent data on MSI as a predictive factor for outcome of gastroesophageal cancer treatment is reviewed.

[89Zr]Zr-cetuximab PET/CT as biomarker for cetuximab monotherapy in patients with RAS wild-type advanced colorectal cancer.

PURPOSE: One-third of patients with RAS wild-type mCRC do not benefit from anti-EGFR monoclonal antibodies. This might be a result of variable pharmacokinetics and insufficient tumor targeting. We evaluated cetuximab tumor accumulation on [89Zr]Zr-cetuximab PET/CT as a potential predictive biomarker and determinant for an escalating dosing strategy. PATIENTS AND METHODS: PET/CT imaging of [89Zr]Zr-cetuximab (37 MBq/10 mg) after a therapeutic pre-dose (500 mg/m2 ≤ 2 h) cetuximab was performed at the start of treatment. Patients without visual tumor uptake underwent dose escalation and a subsequent [89Zr]Zr-cetuximab PET/CT. Treatment benefit was defined as stable disease or response on CT scan evaluation after 8 weeks. RESULTS: Visual tumor uptake on [89Zr]Zr-cetuximab PET/CT was observed in 66% of 35 patients. There was no relationship between PET positivity and treatment benefit (52% versus 80% for PET-negative, P = 0.16), progression-free survival (3.6 versus 5.7 months, P = 0.15), or overall survival (7.1 versus 9.4 months, P = 0.29). However, in 67% of PET-negative patients, cetuximab dose escalation (750-1250 mg/m2) was applied, potentially influencing outcome in this group. None of the second [89Zr]Zr-cetuximab PET/CT was positive. Eighty percent of patients without visual tumor uptake had treatment benefit, making [89Zr]Zr-cetuximab PET/CT unsuitable as a predictive biomarker. Tumor SUVpeak did not correlate to changes in tumor size on CT (P = 0.23), treatment benefit, nor progression-free survival. Cetuximab pharmacokinetics were not related to treatment benefit. BRAF mutations, right-sidedness, and low sEGFR were correlated with intrinsic resistance to cetuximab. CONCLUSION: Tumor uptake on [89Zr]Zr-cetuximab PET/CT failed to predict treatment benefit in patients with RAS wild-type mCRC receiving cetuximab monotherapy. BRAF mutations, right-sidedness, and low sEGFR correlated with intrinsic resistance to cetuximab.

Impact of upfront randomization for postoperative treatment on quality of surgery in the CRITICS gastric cancer trial.

BACKGROUND: Preoperative randomization for postoperative treatment might affect quality of surgery. In the CRITICS trial (ChemoRadiotherapy after Induction chemotherapy In Cancer of the Stomach), patients were randomized before treatment to receive chemotherapy prior to a D1 + gastrectomy (removal of lymph node station (LNS) 1-9 + 11), followed by either chemotherapy (CT) or chemoradiotherapy (CRT). In this analysis, the influence of upfront randomization on the quality of surgery was evaluated. METHODS: Quality of surgery was analyzed in both study arms using surgicopathological compliance (removal of ≥ 15 lymph nodes), surgical compliance (removal of the indicated LNS), and surgical contamination (removal of LNS that should be left in situ). Furthermore, the 'Maruyama Index of Unresected disease' (MI) was evaluated in both study arms, and validated with overall survival. RESULTS: Between 2007 and 2015, 788 patients with gastric cancer were included in the CRITICS study of which 636 patients were operated with curative intent. No difference was observed between the CT and CRT group regarding surgicopathological compliance (74.8% vs 70.9%, P = 0.324), surgical compliance (43.2% vs 39.2%, P = 0.381), and surgical contamination (59.4% vs 59.9%, P = 0.567). Median MI was 1 in both groups (range CT 0-88 and CRT 0-136, P = 0.700). A MI below 5 was associated with better overall survival (CT: P = 0.009 and CRT: P = 0.013). CONCLUSION: Surgical quality parameters were similar in both study arms in the CRITICS gastric cancer trial, indicating that upfront randomization for postoperative treatment had no impact on the quality of surgery. A Maruyama Index below five was associated with better overall survival.

Evaluation of PET and laparoscopy in STagIng advanced gastric cancer: a multicenter prospective study (PLASTIC-study).

BACKGROUND: Initial staging of gastric cancer consists of computed tomography (CT) and gastroscopy. In locally advanced (cT3-4) gastric cancer, fluorodeoxyglucose positron emission tomography with CT (FDG-PET/CT or PET) and staging laparoscopy (SL) may have a role in staging, but evidence is scarce. The aim of this study is to evaluate the impact and cost-effectiveness of PET and SL in addition to initial staging in patients with locally advanced gastric cancer. METHODS: This prospective observational cohort study will include all patients with a surgically resectable, advanced gastric adenocarcinoma (cT3-4b, N0-3, M0), that are scheduled for treatment with curative intent after initial staging with gastroscopy and CT. The modalities to be investigated in this study is the addition of PET and SL. The primary outcome of this study is the proportion of patients in whom the PET or SL lead to a change in treatment strategy. Secondary outcome parameters are: diagnostic performance, morbidity and mortality, quality of life, and cost-effectiveness of these additional diagnostic modalities. The study recently started in August 2017 with a duration of 36 months. At least 239 patients need to be included in this study to demonstrate that the diagnostic modalities are break-even. Based on the annual number of gastrectomies in the participating centers, it is estimated that approximately 543 patients are included in this study. DISCUSSION: In this study, it is hypothesized that performing PET and SL for locally advanced gastric adenocarcinomas results in a change of treatment strategy in 27% of patients and an annual cost-reduction in the Netherlands of €916.438 in this patient group by reducing futile treatment. The results of this study may be applicable to all countries with comparable treatment algorithms and health care systems. TRIAL REGISTRATION: NCT03208621 . This trial was registered prospectively on June 30, 2017.

Association between hospital volume and quality of gastric cancer surgery in the CRITICS trial.

BACKGROUND: Studies investigating the association between hospital volume and quality of gastric cancer surgery are lacking. In the present study, the effect of hospital volume on quality of gastric cancer surgery was evaluated by analysing data from the CRITICS (ChemoRadiotherapy after Induction chemotherapy In Cancer of the Stomach) trial. METHODS: Patients who underwent gastrectomy with curative intent in the Netherlands were selected from the CRITICS trial database. Annual hospital volume of participating centres was derived from the Netherlands Cancer Registry. Hospital volume was categorized into very low (1-10 gastrectomies per year per institution), low (11-20), medium (21-30) and high (31 or more), and linked to the CRITICS database. Quality of surgery was analysed by surgicopathological compliance (removal of at least 15 lymph nodes), surgical compliance (removal of indicated lymph node stations) and the Maruyama Index. Postoperative morbidity and mortality were also compared between hospital categories. RESULTS: Between 2007 and 2015, 788 patients were included in the CRITICS study, of whom 494 were analysed. Surgicopathological compliance was higher (86·7 versus 50·4 per cent; P < 0·001), surgical compliance was greater (52·9 versus 19·8 per cent; P < 0·001) and median Maruyama Index was lower (0 versus 6; P = 0·006) in high-volume hospitals compared with very low-volume hospitals. There was no statistically significant difference in postoperative complications or mortality between the hospital volume categories. CONCLUSION: Surgery performed in high-volume hospitals was associated with better surgical quality than surgery carried out in lower-volume hospitals.

Surgical morbidity and mortality after neoadjuvant chemotherapy in the CRITICS gastric cancer trial.

BACKGROUND: In order to determine the optimal combination of perioperative chemotherapy and chemoradiotherapy for Western patients with advanced resectable gastric cancer, the international multicentre CRITICS trial (ChemoRadiotherapy after Induction chemotherapy In Cancer of the Stomach) was initiated. In this trial, patients with resectable gastric cancer were randomised before start of treatment between adjuvant chemotherapy or adjuvant chemoradiotherapy following neoadjuvant chemotherapy plus gastric cancer resection. The purpose of this study was to report on surgical morbidity and mortality in this trial, and to identify factors associated with surgical morbidity. METHODS: Patients who underwent a gastrectomy with curative intent were selected. Logistic regression analyses were used to assess risk factors for developing postoperative complications. RESULTS: Between 2007 and 2015, 788 patients were included in the CRITICS trial, of whom 636 patients were eligible for current analyses. Complications occurred in 296 patients (47%). Postoperative mortality was 2.2% (n = 14). Complications due to anastomotic leakage was cause of death in 5 patients. Failure to complete preoperative chemotherapy (OR = 2.09, P = 0.004), splenectomy (OR = 2.82, P = 0.012), and male sex (OR = 1.55, P = 0.020) were associated with a greater risk for postoperative complications. Total gastrectomy and oesophago-cardia resection were associated with greater risk for morbidity compared with subtotal gastrectomy (OR = 1.88, P = 0.001 and OR = 1.89, P = 0.038). CONCLUSION: Compared to other Western studies, surgical morbidity in the CRITICS trial was slightly higher whereas mortality was low. Complications following anastomotic leakage was the most important factor for postoperative mortality. Important proxies for developing postoperative complications were failure to complete preoperative chemotherapy, splenectomy, male sex, total gastrectomy, and oesophago-cardia resection.

Nationwide comprehensive gastro-intestinal cancer cohorts: the 3P initiative.

BACKGROUND: The increasing sub-classification of cancer patients due to more detailed molecular classification of tumors, and limitations of current trial designs, require innovative research designs. We present the design, governance and current standing of three comprehensive nationwide cohorts including pancreatic, esophageal/gastric, and colorectal cancer patients (NCT02070146). Multidisciplinary collection of clinical data, tumor tissue, blood samples, and patient-reported outcome (PRO) measures with a nationwide coverage, provides the infrastructure for future and novel trial designs and facilitates research to improve outcomes of gastrointestinal cancer patients. MATERIAL AND METHODS: All patients aged ≥18 years with pancreatic, esophageal/gastric or colorectal cancer are eligible. Patients provide informed consent for: (1) reuse of clinical data; (2) biobanking of primary tumor tissue; (3) collection of blood samples; (4) to be informed about relevant newly identified genomic aberrations; (5) collection of longitudinal PROs; and (6) to receive information on new interventional studies and possible participation in cohort multiple randomized controlled trials (cmRCT) in the future. RESULTS: In 2015, clinical data of 21,758 newly diagnosed patients were collected in the Netherlands Cancer Registry. Additional clinical data on the surgical procedures were registered in surgical audits for 13,845 patients. Within the first two years, tumor tissue and blood samples were obtained from 1507 patients; during this period, 1180 patients were included in the PRO registry. Response rate for PROs was 90%. The consent rate to receive information on new interventional studies and possible participation in cmRCTs in the future was >85%. The number of hospitals participating in the cohorts is steadily increasing. CONCLUSION: A comprehensive nationwide multidisciplinary gastrointestinal cancer cohort is feasible and surpasses the limitations of classical study designs. With this initiative, novel and innovative studies can be performed in an efficient, safe, and comprehensive setting.

Discordance in HER2 Status in Gastro-esophageal Adenocarcinomas: A Systematic Review and Meta-analysis.

Trastuzumab combined with chemotherapy is standard of care for HER2 positive advanced gastro-esophageal cancers. The reported prevalence of HER2 discordance between primary tumors and corresponding metastases varies, hampering uniform patient selection for HER2 targeted therapy. This meta-analysis explores the influence of HER2 assessment methods on this discordance and investigates the prevalence of HER2 discordance in gastro-esophageal adenocarcinomas. PubMed, Embase and Cochrane databases were searched until January 2016. Differences in discordance rate between strict and broad(er) definitions of HER2 status were assessed using random-effect pair-wise meta-analysis. Random-effect single-arm meta-analyses were performed to assess HER2 discordance and the prevalence of positive and negative conversion. A significantly lower discordance rate in HER2 status between primary tumors and corresponding metastases was observed using a strict vs. broad definition of HER2 status (RR = 0.58, 95%CI 0.41-0.82), with a pooled discordance rate of 6.2% and 12.2%, respectively. Using the strict definition of HER2 assessment pooled overall discordance was 7% (95%CI 5-10%). The lowest discordance rates between primary tumors and corresponding metastasis are observed when using a strict method of HER2 positivity. Treatment outcomes of different studies will be better comparable if selection of eligible patients for HER2 targeted therapy is based on this strict definition.

Early outcomes from the Dutch Upper Gastrointestinal Cancer Audit.

BACKGROUND: In 2011, the Dutch Upper Gastrointestinal Cancer Audit (DUCA) group began nationwide registration of all patients undergoing surgery with the intention of resection for oesophageal or gastric cancer. The aim of this study was to describe the initiation and implementation of this process along with an overview of the results. METHODS: The DUCA is part of the Dutch Institute for Clinical Auditing. The audit provides (surgical) teams with reliable, weekly updated, benchmarked information on process and (case mix-adjusted) outcome measures. To accomplish this, a web-based registration was designed, based on a set of predefined quality measures. RESULTS: Between 2011 and 2014, a total of 2786 patients with oesophageal cancer and 1887 with gastric cancer were registered. Case ascertainment approached 100 per cent for patients registered in 2013. The percentage of patients with oesophageal cancer starting treatment within 5 weeks of diagnosis increased significantly over time from 32·5 per cent in 2011 to 41·0 per cent in 2014 (P < 0·001). The percentage of patients with a minimum of 15 examined lymph nodes in the resected specimen also increased significantly for both oesophageal cancer (from 50·3 per cent in 2011 to 73·0 per cent in 2014; P < 0·001) and gastric cancer (from 47·5 per cent in 2011 to 73·6 per cent in 2014; P < 0·001). Postoperative mortality remained stable (around 4·0 per cent) for patients with oesophageal cancer, and decreased for patients with gastric cancer (from 8·0 per cent in 2011 to 4·0 per cent in 2014; P = 0·031). CONCLUSION: Nationwide implementation of the DUCA has been successful. The results indicate a positive trend for various process and outcome measures.

Prognostic value of BRAF and KRAS mutation status in stage II and III microsatellite instable colon cancers.

Microsatellite instability (MSI) has been associated with favourable survival in early stage colorectal cancer (CRC) compared to microsatellite stable (MSS) CRC. The BRAF V600E mutation has been associated with worse survival in MSS CRC. This mutation occurs in 40% of MSI CRC and it is unclear whether it confers worse survival in this setting. The prognostic value of KRAS mutations in both MSS and MSI CRC remains unclear. We examined the effect of BRAF and KRAS mutations on survival in stage II and III MSI colon cancer patients. BRAF exon 15 and KRAS exon 2-3 mutation status was assessed in 143 stage II (n = 85) and III (n = 58) MSI colon cancers by high resolution melting analysis and sequencing. The relation between mutation status and cancer-specific (CSS) and overall survival (OS) was analyzed using Kaplan-Meier and Cox regression analysis. BRAF V600E mutations were observed in 51% (n = 73) and KRAS mutations in 16% of cases (n = 23). Patients with double wild-type cancers (dWT; i.e., BRAF and KRAS wild-type) had a highly favourable survival with 5-year CSS of 93% (95% CI 84-100%), while patients with cancers harbouring mutations in either BRAF or KRAS, had 5-year CSS of 76% (95% CI 67-85%). In the subgroup of stage II patients with dWT cancers no cancer-specific deaths were observed. On multivariate analysis, mutation in either BRAF or KRAS vs. dWT remained significantly prognostic. Mutations in BRAF as well as KRAS should be analyzed when considering these genes as prognostic markers in MSI colon cancers.

MiR expression profiles of paired primary colorectal cancer and metastases by next-generation sequencing.

MicroRNAs (miRs) have been recognized as promising biomarkers. It is unknown to what extent tumor-derived miRs are differentially expressed between primary colorectal cancers (pCRCs) and metastatic lesions, and to what extent the expression profiles of tumor tissue differ from the surrounding normal tissue. Next-generation sequencing (NGS) of 220 fresh-frozen samples, including paired primary and metastatic tumor tissue and non-tumorous tissue from 38 patients, revealed expression of 2245 known unique mature miRs and 515 novel candidate miRs. Unsupervised clustering of miR expression profiles of pCRC tissue with paired metastases did not separate the two entities, whereas unsupervised clustering of miR expression profiles of pCRC with normal colorectal mucosa demonstrated complete separation of the tumor samples from their paired normal mucosa. Two hundred and twenty-two miRs differentiated both pCRC and metastases from normal tissue samples (false discovery rate (FDR) <0.05). The highest expressed tumor-specific miRs were miR-21 and miR-92a, both previously described to be involved in CRC with potential as circulating biomarker for early detection. Only eight miRs, 0.5% of the analysed miR transcriptome, were differentially expressed between pCRC and the corresponding metastases (FDR <0.1), consisting of five known miRs (miR-320b, miR-320d, miR-3117, miR-1246 and miR-663b) and three novel candidate miRs (chr 1-2552-5p, chr 8-20656-5p and chr 10-25333-3p). These results indicate that previously unrecognized candidate miRs expressed in advanced CRC were identified using NGS. In addition, miR expression profiles of pCRC and metastatic lesions are highly comparable and may be of similar predictive value for prognosis or response to treatment in patients with advanced CRC.

KRAS and BRAF mutations are rare and related to DNA mismatch repair deficiency in gastric cancer from the East and the West: results from a large international multicentre study.

BACKGROUND: Inhibitors of the epidermal growth factor (EGFR) signaling pathway have a major role in the treatment of KRAS wild-type colorectal cancer patients. The EGFR pathway has been shown to be activated in gastric cancer (GC). However, published data on KRAS and BRAF mutation status is limited in GC and has not been compared between GC from different geographic regions. METHODS: The prevalence of KRAS and BRAF mutations was established in 712 GC: 278 GC from the United Kingdom, 230 GC from Japan and 204 GC from Singapore. The relationship between KRAS/BRAF mutation status, DNA mismatch repair (MMR) status, clinicopathological variables and overall survival was analysed. RESULTS: Overall, 30 (4.2%) GC carried a KRAS mutation. In total, 5.8% of the UK GC, 4% of Japan GC and 1.5% of Singapore GC were KRAS mutant. KRAS mutant GC had fewer lymph node metastases in the UK cohort (P=0.005) and were more frequent in elderly patients in the Japan cohort (P=0.034). KRAS mutations were more frequent in MMR-deficient GC in the UK and the Japanese cohort (P<0.05). A BRAF mutation was only detected in a single Japanese GC. CONCLUSIONS: This large multicentre study demonstrated that KRAS mutations and DNA MMR deficiency have a role in a small subgroup of GC irrespective of country of origin, suggesting that this subgroup of GC may have developed along a common pathway. Further studies need to establish whether concomitant mutations or amplifications of other EGFR signalling pathway genes may contribute to the activation of this pathway in GC.

Preoperative chemotherapy does not influence the number of evaluable lymph nodes in resected gastric cancer.

BACKGROUND: While it is suggested that more than 15 lymph nodes (LNs) should be evaluated for accurate staging of gastric cancer, LN yield in western countries is generally low. The effect of preoperative chemotherapy on LN yield in gastric cancer is unknown. The aim of the present study is to determine whether preoperative chemotherapy is associated with any difference in the number of LNs obtained from specimens of patients who underwent curative surgery for gastric adenocarcinoma. PATIENTS AND METHODS: In 1205 patients from Memorial Sloan-Kettering Cancer Center (MSKCC) and 1220 patients from the Netherlands Cancer Registry (NCR) who underwent a gastrectomy with curative intent for gastric adenocarcinoma without receiving preoperative radiotherapy, LN yield was analyzed, comparing patients who received preoperative chemotherapy and patients who received no preoperative therapy. RESULTS: Of the 2425 patients who underwent a gastrectomy, 14% received preoperative chemotherapy. Median LN yields were 23 at MSKCC and 10 in the NCR. Despite this twofold difference in LN yield between the two populations, with multivariate Poisson regression, chemotherapy was not associated with LN yield of either population. Variables associated with increased LN yield were institution, female sex, lower age, total (versus distal) gastrectomy and increasing T-stage. CONCLUSIONS: In this patient series, treatment at MSKCC, female sex, lower age, total gastrectomy and increasing primary tumor stage were associated with a higher number of evaluated LNs. Preoperative chemotherapy was not associated with a decrease in LN yield. Evaluating more than 15 LNs after gastrectomy is feasible, with or without preoperative chemotherapy.

Small bowel adenocarcinoma copy number profiles are more closely related to colorectal than to gastric cancers.

BACKGROUND: Small bowel adenocarcinoma (SBA) is a rare cancer and consequently, the options for clinical trials are limited. As they are treated according to either a colorectal or a gastric cancer regimen and the molecular biology of a tumor is a pivotal determinant for therapy response, chromosomal copy number aberrations were compared with the colorectal and gastric adenocarcinomas. MATERIALS AND METHODS: A total of 85 microsatellite stable (MSS) adenocarcinomas from the stomach, colorectum and small bowel were selected from existing array comparative genomic hybridization (aCGH) datasets. We compared the aCGH profiles of the three tumor sites by supervised analysis and hierarchical clustering. RESULTS: Hierarchical clustering revealed substantial overlap of 27 SBA copy number profiles with matched colorectal adenocarcinomas but less overlap with profiles of gastric adenocarcinomas. DNA copy number aberrations located at chromosomes 1p36.3-p34.3, 4p15.3-q35.2, 9p24.3-p11.1, 13q13.2-q31.3 and 17p13.3-p13.2 were the strongest features discriminating SBAs and colorectal adenocarcinomas from gastric adenocarcinomas. CONCLUSIONS: We show that MSS SBAs are more similar to colorectal than to gastric cancer, based on the 27 genome-wide DNA copy number profiles that are currently available. These molecular similarities provide added support for treatment of MSS small bowel cancers according to colorectal cancer regimens.