Differences in the histological findings, phenotypic marker expressions and genetic alterations between adenocarcinoma of the gastric cardia and distal stomach

Identifying the optimal treatment strategy in patients with resectable non-cardia gastric cancer

BACKGROUND

Multimodal treatment strategy including perioperative chemotherapy (PEC), postoperative chemoradiation therapy (POCR), and postoperative chemotherapy (POC) has been accepted as the standard of care in gastric cancer (GC). The ideal sequence and type of therapy remain undetermined.

METHOD

The National Cancer Database was examined from 2006 to 2016 to identify patients with resectable non-cardia gastric cancer. Patient outcomes were compared based on the receipt of PEC, POCR, and POC. This comparison was repeated in a sub-group of patients who received optimal treatment. Optimal treatment was defined as initial chemotherapy within 45 days of diagnosis, resection within 45 days of diagnosis, negative margins, adjuvant chemotherapy within 90 days of resection and standard radiation dose (45 Gy). Kaplan-Meier test, log-rank test, and multivariable analysis (MVA) were performed.

RESULTS

We identified 9589 patients. Median survival was greater in the PEC group followed by POCR and POC (60.6, 42.3, and 31.2 months, respectively). On MVA, factors associated with worse overall survival included age above median (≥ 63 years), Charlson-Deyo score of ≥ 1, non-academic/research program, poorly differentiated/undifferentiated grade, positive margins, and positive lymph nodes. Both PEC and POCR were associated with improved survival when compared to POC (HR 0.78 and 0.79; p < 0.001). When compared with PEC, no significant difference was noted with POCR (HR 1.01; p = 0.987). These results were maintained in optimally treated cohort (n = 3418).

CONCLUSION

In patients with resectable non-cardia gastric cancer, both perioperative chemotherapy and postoperative chemoradiation therapy were associated with improved survival when compared to postoperative chemotherapy. No difference was noted between perioperative chemotherapy and postoperative chemoradiation therapy. These results were maintained in the optimally treated cohort.

The Role of Mucin Expression in the Diagnosis of Oesophago-Gastric Cancer: A Systematic Literature Review

Survival in oesophago-gastric cancer (OGC) is poor due to early diagnostic challenges. Non-invasive risk stratification may identify susceptible patients with pre-malignant or benign disease. Following diagnostic confirmation with endoscopic biopsy, early OGC may be treated sooner. Mucins are transmembrane glycoproteins implicated in OGC with potential use as biomarkers of malignant transformation. This systematic review defines the role of mucins in OGC diagnosis. A literature search of MEDLINE, Web of Science, Embase and Cochrane databases was performed following PRISMA protocols for studies published January 1960-December 2022. Demographic data and data on mucin sampling and analysis methods were extracted. The review included 124 studies (n = 11,386 patients). Gastric adenocarcinoma (GAc) was the commonest OG malignancy (n = 101) followed by oesophageal adenocarcinoma (OAc, n = 24) and squamous cell carcinoma (OSqCc, n = 10). Mucins MUC1, MUC2, MUC5AC and MUC6 were the most frequently implicated. High MUC1 expression correlated with poorer prognosis and metastases in OSqCc. MUC2 expression decreases during progression from healthy mucosa to OAc, causing reduced protection from gastric acid. MUC5AC was upregulated, and MUC6 downregulated in GAc. Mucin expression varies in OGC; changes may be epigenetic or mutational. Profiling upper GI mucin expression in OGC, with pre-malignant, benign and healthy controls may identify potential early diagnostic biomarkers.

Does non-metastatic gastric cancer of the cardia warrant a different treatment strategy?

BACKGROUND

Multimodal treatment strategies with surgery as its centerpiece have been accepted as the standard of care in nonmetastatic cardia gastric cancer (CGC). There remains a lack of consensus regarding the optimal multimodal treatment strategy.

METHOD

We queried National Cancer Database from 2004 to 2016 to identify patients with resected nonmetastatic CGC who received perioperative chemotherapy (PEC), postoperative chemoradiation therapy (POCR), or postoperative chemotherapy (POC). A subgroup analysis was performed in optimally treated patients defined as initial chemotherapy within 45 days of diagnosis, resection within 45 days of diagnosis, negative margins, adjuvant chemotherapy within 90 days of resection, and standard radiation dose (45 Gy). Kaplan-Meier, Univariate analysis (UVA), and Multivariable analysis (MVA) were performed.

RESULTS

We identified 2387 patients. Median survival was 38.8 months in the PEC group, 36 months in the POCR group, and 32.3 months in the POC group (p = 0.1025). On UVA, patients treated with PEC had an association with improved survival (HR, 0.83; p = 0.037) when compared with POC. On MVA, no significant difference was noted in overall survival (OS) between PEC, POCR, and POC, similar to subgroup analysis of optimally treated cohort.

CONCLUSION

OS rate in nonmetastatic CGC is not significantly different between patients receiving PEC, POCR, or POC.

Genomic Heterogeneity and Clonal Evolution in Gastroesophageal Junction Cancer Revealed by Single Cell DNA Sequencing

Gastroesophageal junction (GEJ) cancer is a tumor that occurs at the junction of stomach and esophagus anatomically. GEJ cancer frequently metastasizes to lymph nodes, however the heterogeneity and clonal evolution process are unclear. This study is the first of this kind to use single cell DNA sequencing to determine genomic variations and clonal evolution related to lymph node metastasis. Multiple Annealing and Looping Based Amplification Cycles (MALBAC) and bulk exome sequencing were performed to detect single cell copy number variations (CNVs) and single nucleotide variations (SNVs) respectively. Four GEJ cancer patients were enrolled with two (Pt.3, Pt.4) having metastatic lymph nodes. The most common mutation we found happened in the TTN gene, which was reported to be related with the tumor mutation burden in cancers. Significant intra-patient heterogeneity in SNVs and CNVs were found. We identified the SNV subclonal architecture in each tumor. To study the heterogeneity of CNVs, the single cells were sequenced. The number of subclones in the primary tumor was larger than that in lymph nodes, indicating the heterogeneity of primary site was higher. We observed two patterns of multi-station lymph node metastasis: one was skip metastasis and the other was to follow the lymphatic drainage. Taken together, our single cell genomic analysis has revealed the heterogeneity and clonal evolution in GEJ cancer.

Is cardia cancer a special type of gastric cancer? A differential analysis of early cardia cancer and non-cardia cancer

Background: The prognosis of early cardia cancer and non-cardia cancer is still controversial. It is difficult to collect a large number of cases with complete information in clinical practice. Our study was aimed to identify the differences in clinicopathological characteristics and outcomes of early cardia gastric cancer and non-cardia gastric cancer. Methods: All cases analyzed were from Surveillance, Epidemiology, and End Results database. The data of the patients with early gastric cancer from 2004 to 2010 was retrospectively analyzed. Patients were distributed to cardia cancer group and non-cardia cancer group. Univariate and multivariate analyses were performed to examine differences between groups. The competitive risk model was made to compare the association with cardia cancer and non-cardia cancer about the causes of death. Propensity score matching (PSM) was performed to reduce the bias. Results: We found that cardia cancer was more common in male patients and the White than that in non-cardia cancer at early stage, signet ring cell carcinoma was more common in non-cardia cancer, and the differentiation of non-cardia cancer was worse. Univariate analysis showed that age, marital status, race, tumor location, histology, grade, stage, and operation or not can determine the prognosis. And the prognosis of patients with cardia cancer was worse than that of non-cardia cancer, according to lymph node metastasis and the depth of tumor invasion. Multivariate analysis showed cardia cancer was an independent prognostic factor for poor prognosis. After PSM, cardia cancer still exhibited poor prognosis. Conclusions: At early stage, cardia cancer had a poor prognosis compared with non-cardia cancer. The prevention and treatment of early cardia cancer need to be seriously treated.

Factors Associated with Worse Outcome in Early Stage Gastric Cancer Using the Surveillance, Epidemiology, and End Results (SEER) Database

Background The benefit of adjuvant treatment in gastric adenocarcinoma patients with involvement of the muscularis propria but not beyond is unclear. We aim to establish a model that identifies the factors that adversely affect the prognosis in these patients. Methods We used the Surveillance, Epidemiology, and End Results (SEER) database to identify subjects with stage T2aN0M0 gastric adenocarcinoma who had tumor resection between 2004 and 2015. Data pertaining to the following variables were collected: age, gender, ethnicity, tumor size, grade, site, number of lymph nodes (LNs) being examined, and extent of surgery. Results A total of 1307 patients met our inclusion criteria. The five-year overall survival (OS) was 65%. The following factors were significantly associated with a shorter OS in univariate analysis. Age > 60 years, non-Hispanic whites and non-Hispanic blacks, patients with less than 15 lymph nodes examined at the time of surgery, tumors at the fundus and cardia of the stomach, and those who underwent endoscopic resection or had partial esophagectomy. On multivariate Cox regression, the following factors were predictors for worse OS: age > 60 years with a hazards ratio (HR) = 2.03 (95% CI: 1.49-2.76), patients with less than 15 lymph nodes examined with HR = 1.72 (95% CI: 1.34-2.20), non-Hispanic whites and non-Hispanic blacks with HR = 1.62 (95% CI: 1.26-2.08), and tumors within the cardia and fundus of the stomach with HR = 1.51 (95% CI: 1.21-1.89). Conclusion Patients with stage T2aN0M0 gastric cancer who had their tumor located at the cardia or fundus of the stomach or those with inadequate lymph nodes resection had inferior survival and could potentially benefit from adjuvant chemotherapy.

Characteristics of proximal early gastric cancer differentiating distal early gastric cancer

Previous studies reported substantial differences between proximal and distal gastric cancer, however, most of the cases included in these studies were advanced gastric cancers (AGCs). The aim of this study was to investigate the unique characteristics of proximal early gastric cancer (EGC) by comparing with distal EGC. From March 2007 to March 2016, proximal and distal EGC patients who underwent endoscopic or surgical resection at our institution were matched 1:3 according to age and sex. We retrospectively analyzed the clinical and histopathological information. A total of 368 patients were enrolled including 92 (25%) in the proximal and 276 (75%) in the distal group. The proportion of patients who underwent surgery (56.5 vs. 20.3%, p<0.001), undifferentiated type (38.0 vs. 19.6%, p<0.001), tumor size (29.5 ±19.4 vs. 20.3 ±16.8 mm, p<0.001) and submucosal (SM) invasion (60.9 vs. 25.7%, p<0.001) were significantly higher in the proximal group than in the distal group. In multivariate analysis, the proximal location of EGC was a significant risk factor for SM invasion in the total population (odds ratio [OR], 3.541; 95% confidence interval [CI], 2.053–6.110; p<0.001), and in subgroup with EGC < 30mm (n = 279) (OR, 5.940; 95% CI, 2.974–11.862; p<0.001). In conclusion, careful therapeutic decision of proximal EGC is essential due to the different histopathological characteristics such as large tumor size and higher potential for SM invasion.

Targeted therapies for advanced and metastatic adenocarcinoma of the gastroesophageal junction: is there something new?

Despite improvements in systemic chemotherapy (CT), the prognosis of metastatic adenocarcinoma of the gastroesophageal junction remains poor. Over the years, new targeting agents have become available and were tested, with or without CT, in first or subsequent lines of therapy. The epidermal growth factor receptor family was targeted with monoclonal antibodies (MoAbs) (trastuzumab, cetuximab, panitumumab) and tyrosin kinase inhibitors (TKIs) (lapatinib, erlotinib, gefitinib). Only trastuzumab, in combination with cisplatin and fluoropyrimidines, significantly improved overall survival (OS) in first-line therapy (13.8 vs. 11.1 months). Angiogenesis also was targeted with MoAbs (bevacizumab and ramucirumab); ramucirumab, a vascular endothelial growth factor-receptor 2 antagonist, enhanced OS in two phase III studies in the first (9.6 vs. 7.4 months) and subsequent lines of treatment (5.2 vs. 3.8 months), while the bevacizumab study was negative. TKIs (sunitinib, sorafenib, regorafenib, apatinib) were tested in this setting in phase II studies in the second/third line, only showing modest antitumor activity. The hepatocyte growth factor receptor (MET) was targeted in untreated patients in a phase III trial with MoAb rilotumumab, with or without CT, but the study was stopped because of mortality excess in the rilotumumab arm. Mammalian target of rapamycin (MTOR) pathway inhibition with everolimus was tested in pretreated patients in a placebo-controlled phase III trial who failed to improve OS (5.4 vs. 4.3 months). In conclusion, considering the modest survival gain obtained overall, the high cost of these therapies and the quality of life issue must be primarily considered in treating these patients.

UCH-LI acts as a novel prognostic biomarker in gastric cardiac adenocarcinoma

Gastric cardiac adenocarcinoma (GCA) accounts for a majority of gastric cancer population and harbors unfavorable outcome. Ubiquitin C-terminal hydrolase L1 (UCH-L1) belongs to the deubiquitinating enzyme family, which could regulate cell growth in human cancers. In the present study, expression of UCH-L1 was evaluated in 196 GCAs by immunohistochemistry using tissue microarray and its function on gastric cancer cells was measured. UCH-L1 expression was increased in GCA specimens, compared with their normal tissues and UCH-L1 overexpression is tightly correlated with tumor size and overall TNM stage. Log-rank analysis showed that UCH-L1 positive is reversely associated with cumulative survival (P<0.001). Multivariate Cox regression model showed that UCH-L1 overexpression is a remarkably negative predictor in GCA prognosis (Hazard Ratio=0.53, P<0.01), along with advanced TNM stage that is a known negative factor in gastric cancers (Hazard Ratio=0.33, P<0.05). Silencing of UCH-L1 reduced the ability of cell proliferation, colony formation, migration and invasion of gastric cancer cells. Our findings suggest that UCH-L1 is a promising prognostic biomarker for GCAs and might play an important role in the carcinogenesis of gastric cancer.

Retrospective review using targeted deep sequencing reveals mutational differences between gastroesophageal junction and gastric carcinomas

BACKGROUND

Adenocarcinomas of both the gastroesophageal junction and stomach are molecularly complex, but differ with respect to epidemiology, etiology and survival. There are few data directly comparing the frequencies of single nucleotide mutations in cancer-related genes between the two sites. Sequencing of targeted gene panels may be useful in uncovering multiple genomic aberrations using a single test.

METHODS

DNA from 92 gastroesophageal junction and 75 gastric adenocarcinoma resection specimens was extracted from formalin-fixed paraffin-embedded tissue. Targeted deep sequencing of 46 cancer-related genes was performed through emulsion PCR followed by semiconductor-based sequencing. Gastroesophageal junction and gastric carcinomas were contrasted with respect to mutational profiles, immunohistochemistry and in situ hybridization, as well as corresponding clinicopathologic data.

RESULTS

Gastroesophageal junction carcinomas were associated with younger age, more frequent intestinal-type histology, more frequent p53 overexpression, and worse disease-free survival on multivariable analysis. Among all cases, 145 mutations were detected in 31 genes. TP53 mutations were the most common abnormality detected, and were more common in gastroesophageal junction carcinomas (42% vs. 27%, p = 0.036). Mutations in the Wnt pathway components APC and CTNNB1 were more common among gastric carcinomas (16% vs. 3%, p = 0.006), and gastric carcinomas were more likely to have ≥3 driver mutations detected (11% vs. 2%, p = 0.044). Twenty percent of cases had potentially actionable mutations identified. R132H and R132C missense mutations in the IDH1 gene were observed, and are the first reported mutations of their kind in gastric carcinoma.

CONCLUSIONS

Panel sequencing of routine pathology material can yield mutational information on several driver genes, including some for which targeted therapies are available. Differing rates of mutations and clinicopathologic differences support a distinction between adenocarcinomas that arise in the gastroesophageal junction and those that arise in the stomach proper.

Clinical significance of MYT1L gene polymorphisms in Chinese patients with gastric cancer

BACKGROUND

Myelin transcription factor 1 (MYT1) and its homologue MYT1-like (MYT1L) are the two main members of MYT/NZF family transcription factors, which are highly related, share a high degree of identity and show similar regulatory functions in neural development. There are evidences from several cytology experiments showing that MYT1 is associated with carcinoma.

METHODOLOGY/PRINCIPAL FINDINGS

In the present study, we genotyped 944 surgically resected gastric cancer patients by the SNaPshot method to explore the association of MYT1L rs17039396 polymorphism with survival of gastric cancer in a Chinese population. We found that cardia cancer patients carrying MYT1L rs17039396 GG genotype survived for a significantly shorter time than those carrying the GA genotype. This significance was enhanced in the dominant model (GG vs. GA/AA, log-rank P = 0.001), suggesting a potential protect role of the variant A allele. Multivariate Cox regression analyses showed that the AG/GG genotypes were associated with a significantly decreased risk of death from gastric cancer (adjusted hazard ratio (HR) = 0.57, 95% confidence interval (CI) = 0.40-0.81). Stratification analyses further showed that such protective effect was statistically significant in subgroups of patients with tumor size ≤5 cm (adjusted HR = 0.34, 95%CI = 0.19-0.64), well-moderate gastric cancer (adjusted HR = 0.59, 95%CI = 0.35-0.98), no lymph-node metastasis (adjusted HR = 0.49, 95%CI = 0.31-0.76), no distant metastasis (adjusted HR = 0.59, 95%CI = 0.41-0.84).

CONCLUSIONS/SIGNIFICANCE

In conclusion, these data represents the first demonstration that MYT1L rs17039396 variants could indentified as a favorable prognostic indicator for gastric cancer, particularly among the cardia gastric cancer. Further validation in other larger studies with different ethnic populations and functional evaluations are needed.

Putative role of the mTOR/4E-BP1 signaling pathway in the carcinogenesis and progression of gastric cardiac adenocarcinoma

The mammalian target of rapamycin/eukaryotic translation inititiation factor 4E binding protein 1 (mTOR/4E-BP1) transduction pathway is activated in a range of malignant cancers, but its role in human gastric cardiac adenocarcinoma (GCA) has not been well defined. The present study used western blotting and reverse transcription polymerase chain reaction (RT-PCR) to assess the expression of mTOR, 4E-BP1 and eukaryotic translation initiation factor 4E (eIF4E) at the protein and mRNA levels in 33 cases of GCA and paired adjacent normal gastric mucosal tissues. The expression of mTOR at the protein level in GCA was significantly lower than that in the corresponding normal gastric mucosa (0.296 ± 0.27 vs. 1.348 ± 0.80, P<0.05), but the ratio of p-mTOR to mTOR was significantly increased in tumor tissues (1.425 ± 1.07 vs. 0.450 ± 0.24, P<0.05). The expression of 4E-BP1 was significantly decreased in GCA compared with normal tissues (p<0.05), while the levels of phosphorylated 4E-BP1 (p-4E-BP1) were markedly increased in tumor tissues (p<0.05). The levels of phosphorylated eIF4E (p‑eIF4E) were significantly higher in the tumors in comparison to the corresponding normal tissues (1.822 ± 0.63 vs. 0.997 ± 0.38, P<0.05), and the levels of p-eIF4E were closely correlated with lymph node metastasis (p<0.05). The mTOR/4E-BP1 signaling pathway is activated in GCA, with mTOR activated mainly through increased mTOR phosphorylation rather than protein overexpression.

Meta-analysis demonstrates that the NAD(P)H: quinone oxidoreductase 1 (NQO1) gene 609 C>T polymorphism is associated with increased gastric cancer risk in Asians

The association between the NAD(P)H: quinone oxidoreductase 1 (NQO1) gene C609T polymorphism and gastric cancer has been widely evaluated, yet with conflicting results. Data were available from seven study populations involving 2600 subjects. Overall, comparison of alleles 609T and 609C indicated a significantly increased risk (46%) for gastric cancer (95% confidence interval (95%CI) for odds ratio (OR) = 1.20-1.79) in individuals with the T allele. The tendency was increased in the homozygous comparison (609TT versus 609CC), with an OR = 2.04 (95%CI = 1.37-3.05). Stratified analysis by study design demonstrated stronger associations in population-based studies than in hospital-based studies, based on OR. Ethnicity-based analysis demonstrated a significant association in Asians but not in Caucasians. Additionally, in the subgroup analyses by the type of gastric cancer, a significantly increased risk was found with all genetic models in the gastric adenocarcinoma subgroup compared to the others. We conclude that the NQO1 gene C609T polymorphism increases the risk for gastric cancer, especially in Asian populations.

Keratin 17 expression correlates with tumor progression and poor prognosis in gastric adenocarcinoma

BACKGROUND

Keratin 17 (K17) is regarded as a basal/myoepithelial cell keratin and is known to be inducible in activated keratinocytes. The high frequency of K17 expression in pancreaticobiliary nonmucinous adenocarcinoma or basal-like breast carcinoma has previously been described. However, its expression in gastric cancer (GC) is controversial.

METHODS

We investigated the clinicopathological features and prognostic significance of 192 patients with GC by immunohistochemical staining of tissue microarrays. Analysis of epithelial markers including K17, K14, and K5/6, cell cycle-associated proteins p53, Ki-67, and 14-3-3 sigma, and mucinous phenotype markers including CD10, CDX2, MUC5AC, and MUC6 was performed.

RESULTS

Cytoplasmic expression of K17 was observed in 95 (49.5%) of 192 patients with GC. K17 expression positively correlated with lymph node metastasis (P = 0.003) and advanced stages of the disease (P = 0.014). K17 expression was significantly correlated with 14-3-3 sigma expression (P < 0.001) and CD10 expression (P = 0.015). The overall survival rates of patients with K17-positive GC were significantly lower than those with negative K17 expression (50.5 vs. 71.1%, P = 0.004). Univariate analysis revealed that K17 expression confers a poor prognosis in patients with GC (P = 0.004), and it was also an independent prognostic factor in multivariate analysis (P = 0.049).

CONCLUSIONS

K17 expression is correlated with tumor progression in GC and may serve as a biomarker for poor prognosis.

Should adenocarcinoma of the esophagogastric junction be classified as esophageal cancer? A comparative analysis according to the seventh AJCC TNM classification

OBJECTIVE

The aim of this study was to evaluate the adequacy of esophageal classification for adenocarcinoma of the esophagogastric junction (AEJ) of the seventh American Joint Committee on Cancer (AJCC) TNM classification.

BACKGROUND

The seventh AJCC TNM classification proposed the new classification for AEJ as a part of esophageal cancer depending on the esophagogastric junction (EGJ) involvement. However, there are still many controversies over the classification system for AEJ.

METHODS

A review of pathologic reports and photographic findings at Seoul National University Hospital from 2003 to 2009 identified 4524 patients with single, primary adenocarcinoma of the EGJ (n = 497) and other regions of the stomach (GC, n = 4027) who underwent an operation with curative intent. We analyzed the clinicopathologic features and postoperative prognosis of AEJ using the Siewert classification and the seventh AJCC TNM classification.

RESULTS

There was no Siewert type I (AEJ I) in this study. The prognosis of AEJ was similar to that of GC. There was no difference in clinicopathologic features between AEJ II and AEJ III. Even though AEJ extending into the EGJ (AEJe) showed more advanced pathologic features than AEJ not extending into the EGJ (AEJg), the prognosis of AEJe and AEJg was not significantly different when stratified by T stage. Compared with the classification of gastric cancer applied for AEJ, esophageal classification for AEJ from the seventh AJCC TNM classification showed a loss of distinctiveness at each TNM stage.

CONCLUSIONS

To evaluate the postoperative prognosis of AEJ within the stomach, AEJ II and AEJ III should be considered a part of gastric cancer irrespective of EGJ involvement.

Phase II trial of modified FOLFOX6 and erlotinib in patients with metastatic or advanced adenocarcinoma of the oesophagus and gastro-oesophageal junction

BACKGROUND

There is increased recognition that cancers of the upper GI tract comprise distinct epidemiological and molecular entities. Erlotinib has shown activity in patients with adenocarcinoma of the oesophagus/gastro-oesophageal junction (GEJ), but not in distal gastric cancer. mFOLFOX6 is one of several active regimens used to treat adenocarcinoma of the Eso/GEJ. This study evaluates the efficacy and safety of mFOLFOX6 and erlotinib in patients with metastatic or advanced Eso/GEJ cancers.

METHODS

Patients with previously untreated advanced or metastatic Eso/GEJ adenocarcinoma are treated with oxaliplatin 85 mg m(-2), 5-FU 400 mg m(-2), LV 400 mg m(-2) on day 1, 5-FU 2400 mg m(-2) over 48 h and erlotinib 150 mg PO daily. Treatment was repeated every 14 days. The primary objective was response rate (RR), secondary objectives include toxicity, progression-free survival (PFS), overall survival (OS) and to correlate clinical outcome with expression patterns and molecular alterations in the epidermal growth factor receptor-dependent pathways.

RESULTS

A total of 33 patients were treated and evaluable: there were two complete responses, 15 partial responses for an objective RR of 51.5% (95% CI, 34.5-68.6%). Median PFS was 5.5 months (95% CI, 3.1-7.5 months) and median OS was 11.0 months (95% CI, 8.0-17.4 months). The most common grade 3-4 toxicities were: diarrhoea (24%), nausea/vomiting (11%), skin rash (8%) and peripheral neuropathy (8%). The frequency of alterations was KRAS mutations (8%), EGFR mutations (0%) and HER2 amplification (19%).

CONCLUSION

In patients with Eso/GEJ adenocarcinoma, mFOLFOX6 and erlotinib is active, has an acceptable toxicity profile and FOLFOX ± erlotinib could be considered for further development.

Differences of immunophenotypic markers and signaling molecules between adenocarcinomas of gastric cardia and distal stomach

During the past decades, the subsites of gastric carcinoma underwent significant changes. The incidence of the adenocarcinoma at distal stomach has been decreased, whereas cardiac adenocarcinoma remained increasing in many countries. The aim of this study was to investigate the differences between gastric cardiac and distal adenocarcinomas. We detected expressions of cytokeratins (cytokeratins 7, 14, 19, and 20) and mucins (mucins 1, 2, and 5AC) by immunohistochemistry and signaling molecules (p38, mitogen-activated protein kinase-interacting kinase 1 (MNK1), extracellular signal-regulated kinase, Jun N-terminal kinase, and phosphoinositide 3 kinase) by reverse transcription-polymerase chain reaction in both groups. The incidence of mucin 2 expression was lower in total (50.0%) and advanced-stage cases (52.0%) with cardiac adenocarcinomas than those in distal cases with total (70.2%) and advanced stage (71.4%), respectively. However, the staining for cytokeratin 14 was also significantly higher in total or advanced-stage tumors from the cardia. Our data showed no significant difference of cytokeratin 7/cytokeratin 20 pattern between 2 groups, but cytokeratin 20 expression was significantly higher in advanced-stage carcinomas of the cardia (58.7%) than in distal ones with advanced stage (38.3%). A multivariate analysis demonstrated different relationships between immunophenotypic markers and pathologic parameters in adenocarcinomas of the cardia and distal stomach. Moreover, significantly lower expressions of MNK1 and p38 in cardiac tumors were also detected. In summary, we found significant differences in patterns of immunophenotypic markers and expressions of signaling molecules between the 2 groups. It is indicated that adenocarcinoma of the cardia was different in histotype and histologic origin from distal adenocarcinoma. The cardiac adenocarcinoma might be a special subtype or an independent entity of gastric carcinoma in China.

Differences in the molecular biology of adenocarcinoma of the esophagus, gastric cardia, and upper gastric third

Adenocarcinoma of the distal esophagus, gastric cardia, and upper gastric third are grouped in type I-III by the Siewert classification. This classification is based on the endoscopic localisation of the tumor center, and is the most important diagnostic tool to group these tumors. On a molecular level, there is currently no marker that would allow to differentiate the three different types. Furthermore, the Siewert classification was not uniformly used in the recent literature, making interpretation and generalization of these results difficult. However, several potential targets have been identified that may help to separate these tumors by molecular markers, and are summarized in this chapter.

A novel method, digital genome scanning detects KRAS gene amplification in gastric cancers: involvement of overexpressed wild-type KRAS in downstream signaling and cancer cell growth

Background

Gastric cancer is the third most common malignancy affecting the general population worldwide. Aberrant activation of KRAS is a key factor in the development of many types of tumor, however, oncogenic mutations of KRAS are infrequent in gastric cancer. We have developed a novel quantitative method of analysis of DNA copy number, termed digital genome scanning (DGS), which is based on the enumeration of short restriction fragments, and does not involve PCR or hybridization. In the current study, we used DGS to survey copy-number alterations in gastric cancer cells.

Methods

DGS of gastric cancer cell lines was performed using the sequences of 5000 to 15000 restriction fragments. We screened 20 gastric cancer cell lines and 86 primary gastric tumors for KRAS amplification by quantitative PCR, and investigated KRAS amplification at the DNA, mRNA and protein levels by mutational analysis, real-time PCR, immunoblot analysis, GTP-RAS pull-down assay and immunohistochemical analysis. The effect of KRAS knock-down on the activation of p44/42 MAP kinase and AKT and on cell growth were examined by immunoblot and colorimetric assay, respectively.

Results

DGS analysis of the HSC45 gastric cancer cell line revealed the amplification of a 500-kb region on chromosome 12p12.1, which contains the KRAS gene locus. Amplification of the KRAS locus was detected in 15% (3/20) of gastric cancer cell lines (8–18-fold amplification) and 4.7% (4/86) of primary gastric tumors (8–50-fold amplification). KRAS mutations were identified in two of the three cell lines in which KRAS was amplified, but were not detected in any of the primary tumors. Overexpression of KRAS protein correlated directly with increased KRAS copy number. The level of GTP-bound KRAS was elevated following serum stimulation in cells with amplified wild-type KRAS, but not in cells with amplified mutant KRAS. Knock-down of KRAS in gastric cancer cells that carried amplified wild-type KRAS resulted in the inhibition of cell growth and suppression of p44/42 MAP kinase and AKT activity.

Conclusion

Our study highlights the utility of DGS for identification of copy-number alterations. Using DGS, we identified KRAS as a gene that is amplified in human gastric cancer. We demonstrated that gene amplification likely forms the molecular basis of overactivation of KRAS in gastric cancer. Additional studies using a larger cohort of gastric cancer specimens are required to determine the diagnostic and therapeutic implications of KRAS amplification and overexpression.

Unclassified mucin phenotype of gastric adenocarcinoma exhibits the highest invasiveness

BACKGROUND AND AIM

Gastric cancers present with distinctive carcinogenesis pathways that vary with the mucin phenotypes. We attempted to elucidate the relations between the characteristics of the mucin phenotypes of gastric cancer and the tumor invasiveness.

METHODS

Gastric adenocarcinomas that were resected surgically between August 2005 and April 2007 were included in the present study. The gastric cancers were subclassified into gastric and intestinal mucin phenotypes if more than 10% of cancer cells exhibited gastric (MUC5AC and/or MUC6) and intestinal (MUC2 or CD10) markers, respectively.

RESULTS

The mucin phenotypes of 123 gastric cancers were gastric (n = 31), intestinal (n = 43), mixed (n = 28) and unclassified (n = 21). The mucin phenotype was related to histological type (P < 0.001), Lauren's classification (P = 0.001) and size (P = 0.014) of the gastric adenocarcinoma, but not to its location or to the presence of Helicobacter pylori infection. The unclassified mucin phenotype exhibited the largest number of lymph node metastases (P = 0.007), lymphatic invasions (P < 0.001) and neural invasions (P = 0.026), whereas the intestinal mucin phenotype exhibited the lowest invasiveness.

CONCLUSION

The mucin phenotype reflects the biological behavior of gastric cancer, with the intestinal and unclassified mucin phenotypes exhibiting the lowest and highest invasiveness, respectively.

An orthotopic nude mouse model for preclinical research of gastric cardia cancer

PURPOSE

A clinically relevant animal model for cancer of the esophagogastric junction does not exist. This study aimed to establish an orthotopic mouse model for human gastric cancer of the distal stomach and the gastric cardia.

MATERIALS AND METHODS

Human gastric cancer cell lines AGS, MKN-45, and NCI-N87 were injected subcutaneously into nude mice. These donor tumors were harvested after 4 weeks and minced into small tumor fragments. One donor tumor fragment was orthotopically implanted into the submucosa of either gastric cardia or distal stomach in other mice. The animals were killed 4, 8, and 12 weeks after tumor implantation. Volume of the primary tumor and local and systemic tumor spread were determined.

RESULTS

The implantation technique resulted in a tumor take rate of 100%. An artificial dissemination of tumor cells into the abdominal cavity due to the procedure was not observed.

CONCLUSIONS

We report for the first time the development of a clinically relevant mouse model for human gastric cancer of the gastric cardia and the distal stomach. Primary tumor growth and local and systemic spread progressed continuously during the observation period and mimic the human situation of this disease. This model may be suitable to evaluate novel treatment strategies for this malignancy.

Clinical relevance of EGFR- and KRAS-status in colorectal cancer patients treated with monoclonal antibodies directed against the EGFR

The epidermal growth factor receptor (EGFR) plays an important role in tumorigenesis and tumor progression of colorectal cancer (CRC). As a result, the EGFR has evolved as a relevant target in the treatment of metastatic CRC. KRAS serves as a mediator between extracellular ligand binding and intracellular transduction of signals from the EGFR to the nucleus. The presence of activating KRAS mutations has been identified as a potent predictor of resistance to EGFR-directed antibodies such as cetuximab or panitumumab. These agents should therefore be applied only in tumors with a wild-type status of the KRAS gene. Further parameters of resistance are lack of EGFR amplification, PTEN loss or BRAF mutation. However, they are less well studied or associated with less consistent data and therefore require prospective analyses before integration into clinical decision making. Future studies need to identify patterns of single or multiple mutations to further increase the power of patient selection for anti-EGFR therapy. While molecular parameters help to predict treatment efficacy upfront, skin toxicity has been accepted as an independent predictor of response during exposure to anti-EGFR therapy.

Roles of cyclooxygenase-2 and microsomal prostaglandin E synthase-1 expression and beta-catenin activation in gastric carcinogenesis in N-methyl-N-nitrosourea-treated K19-C2mE transgenic mice

K19-C2mE transgenic (Tg) mice, simultaneously expressing cyclooxygenase-2 (COX-2) and microsomal prostaglandin E synthase-1 (mPGES-1) in the gastric mucosa under the cytokeratin 19 gene promoter, were here treated with N-methyl-N-nitrosourea (MNU) and inoculated with Helicobacter pylori (H. pylori) to investigate gastric carcinogenesis. Wild-type (WT) and Tg mice undergoing MNU treatment frequently developed tumors in the pyloric region (100% and 94.7%, respectively); multiplicity in Tg was higher than that in WT (P < 0.05) with H. pylori infection. Larger pyloric tumors were more frequently observed in Tg than in WT (P < 0.05). In addition, Tg developed fundic tumors, where WT did not. No gastric tumors were observed without MNU treatment. Transcripts of TNF-alpha, iNOS, IL-1beta, and CXCL14 were up-regulated with H. pylori infection in both genotypes and were also increased more in Tg than in WT within H. pylori-inoculated animals. Immunohistochemical analysis demonstrated significantly greater beta-catenin accumulation in pyloric tumors, compared with those in the fundus (P < 0.01) with mutations of exon 3; 18.2% and 31.6% in MNU-alone and MNU + H. pylori-treated WT, whereas 21.4% and 62.5% was observed in the Tg, respectively; the latter significantly higher (P < 0.05), suggesting the role of H. pylori in Wnt activation. In conclusion, K19-C2mE mice promoted gastric cancer in both fundic and pyloric regions. Furthermore beta-catenin activation may play the important role of pyloric carcinogenesis especially in H. pylori-infected Tg. Induction of various inflammatory cytokines in addition to overexpression of COX-2/mPGES-1 could be risk factors of gastric carcinogenesis and may serve as a better gastric carcinogenesis model.