Recent advances in conventional and molecular prognostic factors for gastric carcinoma

Epigenetic Mechanisms and Events in Gastric Cancer-Emerging Novel Biomarkers

Gastric cancer is one of the most common malignancy worldwide. The various genetic and epigenetic events have been found to be associated with its carcinogenesis. The epigenetic is a heritable and transient/reversible change in the gene expression that is not accompanied by modification in the DNA sequence. This event is characterized by the alteration in the promoter CpG island of the gene or histone modification. These events are associated with silencing of critical tumor suppressor gene and activation of oncogenes leading to carcinogenesis. The DNA methylation is a chemical change in the DNA sequence that most commonly occurs at cytosine moiety of CpG dinucleotide and histone, primarily on N- terminal tail that ultimately effect the interaction of DNA with chromatin modifying protein.Hypermethylation of tumor suppressor genes and global hypomethylation of oncogenes are widely studied epigenetic modifications. There are large number of publish reports regarding epigenetic events involving gastric cancer. These changes are potentially useful in identifying markers for early diagnosis and management of this lethal malignancy. Also, role of specific miRNAs and long non coding RNAs in regulation of gene expression is gaining interest and is a matter of further investigation. In this review, we aimed to summarize major epigenetic events (DNA methylation) in gastric cancer along with alteration in miRNAs and long non coding RNAs which plays an important role in pathology of this poorly understood malignancy.

International comparison of the German evidence-based S3-guidelines on the diagnosis and multimodal treatment of early and locally advanced gastric cancer, including adenocarcinoma of the lower esophagus

BACKGROUND

Clinical guidelines are essential in implementing and maintaining nationwide stage-specific diagnostic and therapeutic standards. In 2011, the first German expert consensus guideline defined the evidence for diagnosis and treatment of early and locally advanced esophagogastric cancers. Here, we compare this guideline with other national guidelines as well as current literature.

METHODS

The German S3-guideline used an approved development process with de novo literature research, international guideline adaptation, or good clinical practice. Other recent evidence-based national guidelines and current references were compared with German recommendations.

RESULTS

In the German S3 and other Western guidelines, adenocarcinomas of the esophagogastric junction (AEG) are classified according to formerly defined AEG I-III subgroups due to the high surgical impact. To stage local disease, computed tomography of the chest and abdomen and endosonography are reinforced. In contrast, laparoscopy is optional for staging. Mucosal cancers (T1a) should be endoscopically resected "en-bloc" to allow complete histological evaluation of lateral and basal margins. For locally advanced cancers of the stomach or esophagogastric junction (≥T3N+), preferred treatment is preoperative and postoperative chemotherapy. Preoperative radiochemotherapy is an evidence-based alternative for large AEG type I-II tumors (≥T3N+). Additionally, some experts recommend treating T2 tumors with a similar approach, mainly because pretherapeutic staging is often considered to be unreliable.

CONCLUSIONS

The German S3 guideline represents an up-to-date European position with regard to diagnosis, staging, and treatment recommendations for patients with locally advanced esophagogastric cancer. Effects of perioperative chemotherapy versus chemoradiotherapy are still to be investigated for adenocarcinoma of the cardia and the lower esophagus.

Epigenetic alterations in gastric cancer (Review)

Gastric cancer is one of the most common types of cancer and the second most common cause of cancer-related mortality worldwide. An increasing number of recent studies have confirmed that gastric cancer is a multistage pathological state that arises from environmental factors; dietary factors in particulary are considered to play an important role in the etiology of gastric cancer. Improper dietary habits are one of the primary concerns as they influence key molecular events associated with the onset of gastric carcinogenesis. In the field of genetics, anticancer research has mainly focused on the various genetic markers and genetic molecular mechanisms responsible for the development of this of this disease. Some of this research has proven to be very fruitful, providing insight into the possible mechamisms repsonsible for this disease and into possible treatment modalities. However, the mortality rate associated with gastric cancer remains relatively high. Thus, epigenetics has become a hot topic for research, whereby genetic markers are bypassed and this research is directed towards reversible epigenetic events, such as methylation and histone modifications that play a crucial role in carcinogenesis. The present review focuses on the epigenetic events which play an important role in the development and progression of this deadly disease, gastric cancer.

Biomarkers for gastric cancer: Progression in early diagnosis and prognosis (Review)

Gastric cancer is one of leading causes of cancer-related mortality worldwide and is a notable disease due to its heterogeneity. Recently, numerous studies have investigated the molecular basis of gastric cancer, involving the alteration of pathogenesis, and invasion and metastasis. With the development of modern technologies, various novel biomarkers had been identified that appear to possess diagnostic and prognostic value; therefore, the present review describes our current knowledge of biomarkers for the early diagnosis and prognosis of gastric cancer. Classic biomarkers for gastric cancer diagnosis include carcinoembryonic antigen and cancer antigen 19-9, while microRNA and DNA hypomethylation are proposed as novel biomarkers. Excluding classical biomarkers, biomarkers for determining the progression and prognosis of gastric cancer focus on targeting microRNAs, epigenetic alterations and genetic polymorphisms.

The presence of a micropapillary component predicts aggressive behaviour in early and advanced gastric adenocarcinomas

AIMS

A micropapillary component (MC) consists of small tight clusters of tumour cells surrounded by clear spaces resembling lymphatic tumour emboli. Carcinoma with a MC has recently been described as a highly aggressive variant. However, little is known about the clinicopathological significance of the MC in gastric adenocarcinoma.

METHODS

We investigated the clinicopathological characteristics of gastric adenocarcinoma with a MC and compared them with those of conventional gastric adenocarcinoma.

RESULTS

Among 172 cases, 23 (13.4%) cases had a MC. The amount of micropapillary growth pattern in entire tumour areas ranged from 10% to 80%. The presence of a MC in gastric adenocarcinoma was significantly associated with the depth of invasion, lymph node metastasis, lymphovascular invasion, perineural invasion, higher clinical stages, and poor overall survival rates, but not with age, gender, tumour size, location, and Lauren histological types. The MC was present in four (4.7%) of 86 early gastric cancers and all but one of the early gastric cancers with a MC showed lymph node metastasis (p = 0.02).

CONCLUSIONS

Recognition of a MC in early and advanced gastric adenocarcinomas is very important as it can predict cancer invasion and metastasis leading to a poor clinical outcome.

Survivin -31C/G polymorphism and gastric cancer risk in a Brazilian population

Gastric cancer, despite its decline in incidence, remains a public health problem worldwide, especially in Brazil, where higher incidence indexes are still described. The Survivin gene codifies a multifunctional protein involved in the regulation of the cell cycle and inhibition of the apoptotic pathway, and a polymorphism (-31C/G) located in its promoter region is associated with gene regulation. In order to evaluate the correlation of this polymorphism with gastric cancer risk in a northern Brazil population, we sequenced a fragment containing the polymorphism in individuals with gastric cancer and controls. We observed no differences of alleles and genotype frequencies between cases and controls. However, G carriers of the tumor group had an increased relative risk of developing tumors of diffuse type (OR: 2.22-IC 95%: 0.4835-10.2137), localized in the antrum (OR: 2.16-IC 95%: 0.4811-9.6971) and in younger patients (<50 years-old) (OR: 3.65-IC 95%: 0.4012-33.2429), although with no statistical significance. Nevertheless, C carriers with a high D17S250 microsatellite instability (TP53 gene) show a higher risk to develop gastric tumors (P = 0.0453; OR: 4.1556-IC95%: 0.9716-17.7728), suggesting that the mutate TP53 gene may fail in control and inhibition of Survivin expression, favoring the gastric carcinogenesis. The present result suggests that the presence of the C allele of -31C/G Survivin promoter polymorphism in combination with D17S250 instability may be used as a risk factor for gastric cancer in our population. However, other studies based on a larger sample size are required to properly assess such hypothesis.

Survivin -31C/G polymorphism and gastric cancer risk in a Brazilian population

Gastric cancer, despite its decline in incidence, remains a public health problem worldwide, especially in Brazil, where higher incidence indexes are still described. The Survivin gene codifies a multifunctional protein involved in the regulation of the cell cycle and inhibition of the apoptotic pathway, and a polymorphism (-31C/G) located in its promoter region is associated with gene regulation. In order to evaluate the correlation of this polymorphism with gastric cancer risk in a northern Brazil population, we sequenced a fragment containing the polymorphism in individuals with gastric cancer and controls. We observed no differences of alleles and genotype frequencies between cases and controls. However, G carriers of the tumor group had an increased relative risk of developing tumors of diffuse type (OR: 2.22-IC 95%: 0.4835-10.2137), localized in the antrum (OR: 2.16-IC 95%: 0.4811-9.6971) and in younger patients (<50 years-old) (OR: 3.65-IC 95%: 0.4012-33.2429), although with no statistical significance. Nevertheless, C carriers with a high D17S250 microsatellite instability (TP53 gene) show a higher risk to develop gastric tumors (P = 0.0453; OR: 4.1556-IC95%: 0.9716-17.7728), suggesting that the mutate TP53 gene may fail in control and inhibition of Survivin expression, favoring the gastric carcinogenesis. The present result suggests that the presence of the C allele of -31C/G Survivin promoter polymorphism in combination with D17S250 instability may be used as a risk factor for gastric cancer in our population. However, other studies based on a larger sample size are required to properly assess such hypothesis.

Prognostic role of human equilibrative transporter 1 (hENT1) in patients with resected gastric cancer

Nucleoside transporter proteins are specialized proteins that mediate the transport of nucleosides and nucleoside analog drugs across the plasma membrane. The human equilibrative nucleoside transporter 1 (hENT1) is a member of these proteins and mediates cellular entry of gemcitabine, cytarabine, and fludarabine. The hENT1 expression has been demonstrated to be related with prognosis and activity of gemcitabine-based therapy in breast, ampullary, lung, and pancreatic cancer. We investigated the immunohistochemical expression of hENT in tumor samples from 111 patients with resected gastric adenocarcinoma, correlating these data with clinical parameters and disease outcomes. None of the patients received chemotherapy or radiation therapy before or after surgery as a part of an adjuvant or neoadjuvant program. On univariate survival analysis, the hENT1 expression was associated with overall survival (OS) and disease free survival (DFS). Specifically, those patients with overexpression of hENT1 showed a shorter OS (P = 0.021) and a shorter DFS (P = 0.033). Considering only the node positive patients, higher hENT levels were associated with significantly shorter median DFS (21.7 months; 95% CI 11.1-32.4) compared with patients with low expression of hENT1. The hENT1 expression was defined, in the lymph-node positive patients, as an independent prognostic factor (P = 0.019). Furthermore, considering only patients with diffuse or mixed tumors and lymph-node positive, the expression of hENT1 was strongly related with DFS and OS. Immunohistochemistry for the hENT1 protein carries prognostic information in patients with resected gastric cancer and holds promise as a predictive factor in chemotherapy decisions.

Expression of the antiapoptosis gene Survivin predicts poor prognosis of stage III gastric adenocarcinoma

OBJECTIVE

This study was designed to determine the level of survivin expression and its clinical significance as a prognostic factor in Stage III gastric adenocarcinoma.

METHODS

We performed immunohistochemical staining for survivin, p53 and Bax in formalin-fixed, paraffin-embedded blocks from 157 surgically resected Stage III gastric cancer tissues. To determine the association with clinical course, we reviewed the patients' clinical records.

RESULTS

Of the 157 gastric cancer tissues, 63 (40.1%) cases showed positive expression for survivin protein. There was no significant association between survivin expression and p53 or Bax. For clinicopathologic parameters, large tumor size was closely related to survivin expression (P < 0.05). The 5-year survival rate of patients with positive survivin expression was significantly lower compared with that for survivin-negative cancer patients (P < 0.05). Survivin and p53 were independent prognostic factors in Stage III gastric cancer.

CONCLUSIONS

Survivin protein is an important predictive and prognostic parameter of poor outcome in gastric carcinoma.