Gastric cancer chemoprevention: the current evidence

Histone Methyltransferases Useful in Gastric Cancer Research

Gastric cancer (GC) is one of the most frequent tumors in the world. Stomach adenocarcinoma is a heterogeneous tumor, turning the prognosis prediction and patients’ clinical management difficult. Some diagnosis tests for GC are been development using knowledge based in polymorphisms, somatic copy number alteration (SCNA) and aberrant histone methylation. This last event, a posttranslational modification that occurs at the chromatin level, is an important epigenetic alteration seen in several tumors including stomach adenocarcinoma. Histone methyltransferases (HMT) are the proteins responsible for the methylation in specific amino acids residues of histones tails. Here, were presented several HMTs that could be relating to GC process. We use public data from 440 patients with stomach adenocarcinoma. We evaluated the alterations as SCNAs, mutations, and genes expression level of HMTs in these aforementioned samples. As results, it was identified the 10 HMTs most altered (up to 30%) in stomach adenocarcinoma samples, which are the PRDM14, PRDM9, SUV39H2, NSD2, SMYD5, SETDB1, PRDM12, SUV39H1, NSD3, and EHMT2 genes. The PRDM9 gene is among most mutated and amplified HMTs within the data set studied. PRDM14 is downregulated in 79% of the samples and the SUV39H2 gene is down expressed in patients with recurred/progressed disease. Several HMTs are altered in many cancers. It is important to generate a genetic atlas of alterations of cancer-related genes to improve the understanding of tumorigenesis events and to propose novel tools of diagnosis and prognosis for the cancer control.

Chemopreventive Effects of Dietary Isothiocyanates in Animal Models of Gastric Cancer and Synergistic Anticancer Effects With Cisplatin in Human Gastric Cancer Cells

Naturally occurring isothiocyanates (ITCs) from edible vegetables have shown potential as chemopreventive agents against several types of cancer. The aims of the present study were to study the potential of ITCs in chemoprevention and in potentiating the efficacy of cytotoxic drugs in gastric cancer treatment. The chemoprevention was studied in chemically induced mouse model of gastric cancer, namely N-methyl-N-nitrosourea (MNU) in drinking water, and in a genetically engineered mouse model of gastric cancer (the so-called INS-GAS mice). The pharmacological effects of ITCs with or without cisplatin were studied in human gastric cell lines MKN45, AGS, MKN74 and KATO-III, which were derived from either intestinal or diffused types of gastric carcinoma. The results showed that dietary phenethyl isothiocyanate (PEITC) reduced the tumor size when PEITC was given simultaneously with MNU, but neither when administrated after MNU nor in INS-GAS mice. Treatments of gastric cancer cells with ITCs resulted in a time- and concentration-dependent inhibition on cell proliferation. Pretreatment of gastric cancer cells with ITCs enhanced the inhibitory effects of cisplatin (but not 5-fluorouracil) in time- and concentration-dependent manners. Treatments of gastric cancer cells with PEITC plus cisplatin simultaneously at different concentrations of either PEITC or cisplatin exhibited neither additive nor synergetic inhibitory effect. Furthermore, PEITC depleted glutathione and induced G₂/M cell cycle arrest in gastric cancer cells. In conclusion, the results of the present study showed that PEITC displayed anti-cancer effects, particularly when given before the tumor initiation, suggesting a chemopreventive effect in gastric cancer, and that pretreatment of PEITC potentiated the anti-cancer effects of cisplatin, possibly by reducing the intracellular pool of glutathione, suggesting a possible combination strategy of chemotherapy with pretreatment with PEITC.

Dynamics of Helicobacter pylori infection as a determinant of progression of gastric precancerous lesions: 16-year follow-up of an eradication trial

OBJECTIVE

To evaluate the long-term effect of cumulative time exposed to Helicobacter pylori infection on the progression of gastric lesions.

DESIGN

795 adults with precancerous gastric lesions were randomised to receive anti-H. pylori treatment at baseline. Gastric biopsies were obtained at baseline and at 3, 6, 12 and 16 years. A total of 456 individuals attended the 16-year visit. Cumulative time of H. pylori exposure was calculated as the number of years infected during follow-up. Multivariable logistic regression models were used to estimate the risk of progression to a more advanced diagnosis (versus no change/regression) as well as gastric cancer risk by intestinal metaplasia (IM) subtype. For a more detailed analysis of progression, we also used a histopathology score assessing both severity and extension of the gastric lesions (range 1-6). The score difference between baseline and 16 years was modelled by generalised linear models.

RESULTS

Individuals who were continuously infected with H. pylori for 16 years had a higher probability of progression to a more advanced diagnosis than those who cleared the infection and remained negative after baseline (p=0.001). Incomplete-type IM was associated with higher risk of progression to cancer than complete-type (OR, 11.3; 95% CI 1.4 to 91.4). The average histopathology score increased by 0.20 units/year (95% CI 0.12 to 0.28) among individuals continuously infected with H. pylori. The effect of cumulative time of infection on progression in the histopathology score was significantly higher for individuals with atrophy (without IM) than for individuals with IM (p<0.001).

CONCLUSIONS

Long-term exposure to H. pylori infection was associated with progression of precancerous lesions. Individuals infected with H. pylori with these lesions may benefit from eradication, particularly those with atrophic gastritis without IM. Incomplete-type IM may be a useful marker for the identification of individuals at higher risk for cancer.

Suppressed Helicobacter pylori-associated gastric tumorigenesis in Fat-1 transgenic mice producing endogenous ω-3 polyunsaturated fatty acids

Dietary approaches to preventing Helicobacter pylori (H. pylori)-associated gastric carcinogenesis are widely accepted because surrounding break-up mechanisms are mandatory for cancer prevention, however, eradication alone has been proven to be insufficient. Among these dietary interventions, omega-3-polyunsaturated-fatty acids (ω-3 PUFAs) are often the first candidate selected. However, there was no trial of fatty acids in preventing H. pylori-associated carcinogenesis and inconclusive results have been reported, likely based on inconsistent dietary administration. In this study, we developed an H. pylori initiated-, high salt diet promoted-gastric tumorigenesis model and conducted a comparison between wild-type (WT) and Fat-1-transgenic (TG)-mice. Gross and pathological lesions in mouse stomachs were evaluated at 16, 24, 32, and 45 weeks after H. pylori infection, and the underlying molecular changes to explain the cancer preventive effects were investigated. Significant changes in: i) ameliorated gastric inflammations at 16 weeks of H. pylori infection, ii) decreased angiogenic growth factors at 24 weeks, iii) attenuated atrophic gastritis and tumorigenesis at 32 weeks, and iv) decreased gastric cancer at 45 weeks were all noted in Fat-1-TG-mice compared to WT-mice. While an increase in the expression of Cyclooxygenase (COX)-2, and reduced expression of the tumor suppressive 15-PGDH were observed in WT-mice throughout the experimental periods, the expression of Hydroxyprostaglandin dehydrogenase (15-PGDH) was preserved in Fat-1-TG-mice. Using a comparative protein array, attenuated expressions of proteins implicated in proliferation and inflammation were observed in Fat-1-TG-mice compared to WT-mice. Conclusively, long-term administration of ω-3 PUFAs can suppress H. pylori-induced gastric tumorigenesis through a dampening of inflammation and reduced proliferation in accordance with afforded rejuvenation.

Effectiveness of Helicobacter pylori eradication in the prevention of primary gastric cancer in healthy asymptomatic people: A systematic review and meta-analysis comparing risk ratio with risk difference

BACKGROUND

Helicobacter pylori infection is strongly associated with gastric cancer occurrence. However, it is unclear whether eradication therapy reduces the risk of gastric cancer occurrence. We evaluated whether H. pylori eradication reduces the risk of primary gastric cancer by using both risk ratio (RR) and risk difference (RD).

METHODS

Searches of PubMed, EMBASE, Google scholar, the Cochrane Library, and the Japan Medical Abstracts Society as well as those registered in databases of the Cochrane Central Register of Controlled Trials, metaRegister of Controlled Trials, ClinicalTrials.gov, controlled-trials.com, UMIN-CTR, JMACCT-CTR, and JAPIC-CTI between January 1965 and March 2017, supplemented with manual screening. Randomized controlled trials (RCTs) in which eradication therapy were implemented for the interventional group but not for the control group, and assessed the subsequent occurrence of primary gastric cancer as the main outcome. Two authors independently reviewed articles and extracted data. Integrated results for all data were presented as RR and RD.

RESULTS

Seven studies met inclusion criteria. The reductions in risk of primary gastric cancer occurrence in terms of overall RR and RD were 0.67 (95% CI: 0.48 to 0.95) and -0.00 ([95% CI: -0.01 to 0.00]; number needed to treat: 125.5 [95% CI: 70.0 to 800.9]), respectively.

CONCLUSIONS

The effectiveness of H. pylori eradication therapy in suppressing the occurrence of primary gastric cancer was significant and comparable to that of previous studies in terms of the estimated RR. However, the estimated RD was slight and not statistically significant.

Hereditary diffuse gastric cancer in two families: A case report

Hereditary diffuse gastric cancer (HDGC) is associated with E-cadherin 1 (CDH1) germline mutations. In the present study, two unusual HDGC cases are described. Case 1 was a female with no family history of gastric cancer who developed Hodgkin's lymphoma at 19 years of age, and DGC at 32 years of age. Due to her young age (32 years), the patient was examined for CDH1 abnormalities and a deleterious mutation was identified. Her father and younger sister were identified to be carriers of the mutation. Case 2 was a 36-year-old female diagnosed with lobular breast cancer (LBC); her mother had LBC, and her grandmother had LBC and DGC. The molecular test was wild-type for breast cancer susceptibility genes 1 and 2; however, a large deletion in CDH1 was identified. At prophylactic gastrectomy, early DGC was identified. Early onset of DGC and LBC justifies testing for CDH1. A better knowledge of tumor natural history in carrier subjects is important to aid genetic counseling, in order to assess the surveillance time required prior to carrying out prophylactic surgery.

Risk Factors for Metachronous Recurrence after Endoscopic Submucosal Dissection of Early Gastric Cancer

Although endoscopic submucosal dissection (ESD) is widely accepted as a curative treatment method for early gastric cancer (EGC) worldwide, metachronous recurrence often occurs after ESD for EGC. However, there are insufficient data about the role of Helicobacter pylori (H. pylori) infection and other risk factors for recurrence. We aimed to compare the metachronous lesion in the H. pylori persistent group and the eradicated group, and to identify risk factors for metachronous lesion. We retrospectively analyzed 782 patients who underwent ESD between January 2008 and December 2013. We excluded patients with dysplasia or patients who were not tested for H. pylori infection. One hundred eighty-five patients were enrolled. We studied risk factors for recurrence, and used survival analysis to test. There were 24 patients with metachronous recurrence after ESD for EGC among the group. The incidence of metachronous gastric lesions after ESD for EGC developed more in the over 70-year-old group (P = 0.025) and more in the H. pylori persistent group (P = 0.008). In conclusion, H. pylori infection and old age are independent risk factors for metachronous gastric lesions after ESD in EGC.

P21, COX-2, and E-cadherin are potential prognostic factors for esophageal squamous cell carcinoma

Much research effort has been devoted to identifying prognostic factors for esophageal squamous cell carcinoma (ESCC) by immunohistochemistry; however, no conclusive findings have been reached thus far. We hypothesized that certain molecules identified in previous studies might serve as useful prognostic markers for ESCC. Therefore, the aim of the current study was to validate the most relevant markers showing potential for ESCC prognosis in our prospective esophageal cancer database. A literature search was performed using the PubMed database for papers published between 1980 and 2015 using the following key words: 'esophageal cancer,' 'prognosis,' and 'immunohistochemistry.' Literature selection criteria were established to identify the most widely studied markers, and we further validated the selected markers in a cohort from our single-surgeon team, including 153 esophageal cancer patients treated from 2000 to 2010. A total of 1799 articles were identified, 82 of which met the selection criteria. Twelve markers were found to be the most widely studied, and the validation results indicated that only P21, COX-2, and E-cadherin were independent prognostic factors for ESCC patients in this series. The systemic review and cohort validation suggest that P21, COX-2, and E-cadherin are potential prognostic factors for ESCC, paving the way for more targeted prospective validation in the future.

The hematologic markers as prognostic factors in patients with resectable gastric cancer

BACKGROUND

Recently, many studies have investigated the value of the hematologic markers in the prognosis of gastric cancer (GC). However, most studies only focused on the pre-operative markers. The aim of this study was to investigate the prognostic value of the hematologic markers of resectable GC patients at three different periods of the treatment (preoperative, postoperative and before the first chemotherapy).

METHODS

Clinical data from 451 GC patients were retrospectively collected. Hematologic markers including leukocyte, neutrophil, lymphocyte, red blood cell (RBC), platelet, mean platelet volume (MPV), neutrophil proportion (NP), lymphocyte proportion (LP), neutrophil lymphocyte ratio (NLR), and platelet lymphocyte ratio (PLR) were adopted as potential prognostic biomarkers. The Kaplan-Meier method and Cox regression model were applied to reveal the prognostic significance of the hematologic markers.

RESULTS

Preoperative PLR was independently associated with overall survival (OS) via multivariate analysis (hazard ratio, 1.399; 95% confidence interval, 1.015-1.928; p = 0.04). Elevated PLR predicted a larger tumor size (P< 0.001), deeper tumor invasion (P= 0.035) and elevated level of CEA (P= 0.012).

CONCLUSIONS

Although only high preoperative PLR could serve as an independent unfavorable prognostic factor, other markers such as preoperative and postoperative NLR could also provide additionally prognostic information.

Chemopreventive Activity of MGN-3/Biobran Against Chemical Induction of Glandular Stomach Carcinogenesis in Rats and Its Apoptotic Effect in Gastric Cancer Cells

In the current study, we investigated the chemopreventive activity of arabinoxylan rice bran, MGN-3/Biobran, against chemical induction of glandular stomach carcinogenesis in rats. Gastric cancer was induced by carcinogen methylnitronitrosoguanidine (MNNG), and rats received MNNG alone or MNNG plus Biobran (40 mg/kg body weight) for a total of 8 months. Averaged results from 2 separate readings showed that exposure to MNNG plus Biobran caused gastric dysplasia and cancer (adenocarcinoma) in 4.5/12 rats (9/24 readings, 37.5%), with 3.5/12 rats (7/24 readings, 29.2%) showing dysplasia and 1/12 rats (8.3%) developing adenocarcinoma. In contrast, in rats treated with MNNG alone, 8/10 (80%) developed dysplasia and adenocarcinoma, with 6/10 rats (60%) showing dysplasia and 2/10 rats (20%) developing adenocarcinoma. The effect of combining both agents was also associated with significant suppression of the expression of the tumor marker Ki-67 and remarkable induction in the apoptotic gastric cancer cells via mitochondrial-dependent pathway as indicated by the upregulation in p53 expression, Bax expression, downregulation in Bcl-2 expression, an increase in Bax/Bcl-2 ratio, and an activation of caspase-3. In addition, Biobran treatment induced cell-cycle arrest in the subG1 phase, where the hypodiploid cell population was markedly increased. Moreover, Biobran treatment protected rats against MNNG-induced significant decrease in lymphocyte levels. We conclude that Biobran provides protection against chemical induction of glandular stomach carcinogenesis in rats and may be useful for the treatment of human patients with gastric cancer.

Effect of Helicobacter pylori Eradication and ABO Genotype on Gastric Cancer Development

BACKGROUND

Evidence is lacking regarding how Helicobacter pylori infection status, eradication history, and ABO blood type affect the development of gastric cancer (GC) given the multifactorial and distinctive etiology according to cancer location (noncardia vs cardia) and histologic type (intestinal vs diffuse-type). We evaluated the effect of H. pylori infection status incorporated with H. pylori eradication history and ABO genotype on GC development according to cancer location and histologic type.

METHODS

A case-control study of 997 patients with noncardia GC (NCGC) and 1147 control subjects was performed using risk analyses with 14 factors including H. pylori infection with eradication history and ABO genotype. As final analyses, multivariable logistic regression models were fitted. Additionally, H. pylori infection status with eradication history was tested for its association with age, atrophic gastritis (AG), and intestinal metaplasia (IM).

RESULTS

The ABO genotype with the B allele was associated with a significantly lower risk of NCGC of both histologic types. The reduction in risk for NCGC by adding the B allele was more prominent in diffuse-type than that in the intestinal-type. H. pylori infection with eradication history was associated with a significantly lower risk of NCGC of both histologic types, compared with those without eradication history (odds ratio (OR), 0.22; 95% confidence interval (CI), 0.14-0.34) approaching that of uninfected subjects. Past infection status without an eradication history was associated with older age, AG, and IM.

CONCLUSIONS

H. pylori eradication and the B allele decreased the risks of the intestinal and diffuse-types of NCGC. H. pylori eradication revealed a strong association against developing NCGC. Therefore, it should be considered as a primary measure in NCGC prevention.

Different Pathophysiology of Gastritis in East and West? A Western Perspective

Background

Gastritis results from multifactorial gastric mucosal injury. Helicobacter pylori (Hp) is the main cause, and associated diseases have typical underlying patterns of gastritis. Gastric ulcer and gastric cancer (GC) develop from chronic atrophic corpus gastritis (CAG) which therefore represents the most important pattern. GC incidences in East Asia are substantially higher than elsewhere, and this should be also reflected by higher prevalences of CAG and characteristic differences in pathophysiology compared to the West.

Summary

The few available comparative studies of gastritis in Eastern and Western patients are summarized. The main pathogenic factors of gastritis are discussed together with their limitations to explain local differences in disease outcome. Emphasis was put to also include less well-established pathogenic host and environmental factors of possible impact.

Conclusions

CAG is more prevalent in East Asian areas with high GC incidences than the West. Geographic heterogeneity of associated diseases is due to differences in Hp prevalence and virulence as well as modulating host and environmental factors. The following may contribute to the higher burden of CAG in the East: ABD type of CagA with vacA s1 and babA2 alleles of Hp, host Lewis(b) expression in sej/sej nonsecretors, H. heilmannii, low parietal cell mass, high sodium and nitrate intake, preferences in vegetable and fruit consumption, cigarette smoking, air pollution, alcohol. Conversely, green tea, nonfermented soy products and rice may confer protective effects. Hp is on the decline, but also in a world cleared from this bacterium, differences in host genetics will continue to modify gastric disease outcome together with maintained customs as part of cultural diversity.

Recent developments and innovations in gastric cancer

Gastric cancer has an important place in the worldwide incidence of cancer and cancer-related deaths. It can metastasize to the lymph nodes in the early stages, and lymph node metastasis is an important prognostic factor. Surgery is a very important part of gastric cancer treatment. A D2 lymphadenectomy is the standard surgical treatment for cT1N+ and T2-T4 cancers, which are potentially curable. Recently, the TNM classification system was reorganized, and the margins for gastrectomy and lymphadenectomy were revised. Endoscopic, laparoscopic and robotic treatments of gastric cancer have progressed rapidly with development of surgical instruments and techniques, especially in Eastern countries. Different endoscopic resection techniques have been identified, and these can be divided into two main categories: endoscopic mucosal resection and endoscopic submucosal dissection. Minimally invasive surgery has been reported to be safe and effective for early gastric cancer, and it can be successfully applied to advanced gastric cancer with increasing experience. Cytoreductive surgery and hyperthermıc intraperıtoneal chemotherapy were developed as a combined treatment modality from the results of experimental and clinical studies. Also, hyperthermia increases the antitumor activity and penetration of chemotherapeutics. Trastuzumab which is a monoclonal antibody interacts with human epidermal growth factor (HER) 2 and is related to gastric carcinoma. The anti-tumor mechanism of trastuzumab is not clearly known, but mechanisms such as interruption of the HER2-mediated cell signaling pathways and cell cycle progression have been reported previously. H. pylori is involved in 90% of all gastric malignancies and Japanese guidelines strongly recommend that all H. pylori infections should be eradicated regardless of the associated disease. In this review, we present innovations discussed in recent studies.

Helicobacter pylori in gastric carcinogenesis

Gastric cancer still is a major concern as the third most common cancer worldwide, despite declining rates of incidence in many Western countries. Helicobacter pylori (H. pylori) is the major cause of gastric carcinogenesis, and its infection insults gastric mucosa leading to the occurrence of atrophic gastritis which progress to intestinal metaplasia, dysplasia, early gastric cancer, and advanced gastric cancer consequently. This review focuses on multiple factors including microbial virulence factors, host genetic factors, and environmental factors, which can heighten the chance of occurrence of gastric adenocarcinoma due to H. pylori infection. Bacterial virulence factors are key components in controlling the immune response associated with the induction of carcinogenesis, and cagA and vacA are the most well-known pathogenic factors. Host genetic polymorphisms contribute to regulating the inflammatory response to H. pylori and will become increasingly important with advancing techniques. Environmental factors such as high salt and smoking may also play a role in gastric carcinogenesis. It is important to understand the virulence factors, host genetic factors, and environmental factors interacting in the multistep process of gastric carcinogenesis. To conclude, prevention via H. pylori eradication and controlling environmental factors such as diet, smoking, and alcohol is an important strategy to avoid H. pylori-associated gastric carcinogenesis.

Hydroferrate fluid, MRN-100, provides protection against chemical-induced gastric and esophageal cancer in Wistar rats

In the current study, we examined the protective effect of hydroferrate fluid MRN-100 against the carcinogen methylnitronitrosoguanidine (MNNG)-induced gastric and esophageal cancer in rats. MRN-100 is an iron-based compound composed of bivalent and trivalent ferrates. At 33 weeks post treatment with MNNG, rats were killed and examined for the histopathology of esophagus and stomach; liver, spleen, and total body weight; and antioxidant levels in the blood and stomach tissues. Results showed that 17/20 (85%) gastroesophageal tissues from carcinogen MNNG-treated rats developed dysplasia and cancer, as compared to 8/20 (40%) rats treated with MNNG plus MRN-100. In addition, MRN-100 exerted an antioxidant effect in both the blood and stomach tissues by increasing levels of GSH, antioxidant enzymes SOD, CAT, and GPx, and total antioxidant capacity (TAC) level. This was accompanied by a reduction in the total free-radical and malondialdehyde levels. Furthermore, MRN-100 protected against body and organ weight loss. Thus, MRN-100 exhibited significant cancer chemopreventive activity by protecting tissues against oxidative damage in rats, which may suggest its effectiveness as an adjuvant for the treatment of gastric/esophageal carcinoma.

Preventing metachronous gastric lesions after endoscopic submucosal dissection through Helicobacter pylori eradication

BACKGROUND AND AIM

Metachronous recurrence often occurs after endoscopic submucosal dissection for early gastric cancer, and a method for preventing recurrence is unknown. We aimed to identify risk factors for metachronous lesions, and the effects of aspirin use and Helicobacter pylori eradication on preventing recurrence.

METHODS

A total of 1041 consecutive patients who underwent endoscopic submucosal dissection for early gastric cancer between January 2007 and December 2011 were retrospectively analyzed. Every patient was examined endoscopically at 2, 6, and 12 months after endoscopic submucosal dissection, and then annually. Patients were classified into the metachronous group or non-metachronous group according to the existence of metachronous lesions and subdivided by Helicobacter pylori status into three groups: not infected, eradicated after infection, and not eradicated.

RESULTS

At 39 months' median follow-up, metachronous gastric lesions had developed in 35 patients (3.4%), including 16 with dysplasia and 19 cancers. Metachronous group were significantly older than non-metachronous group (P = 0.02). Although non-metachronous group took aspirin more frequently than metachronous group (15.5% vs 5.7%), the difference was statistically insignificant (P = 0.11). In the not eradicated group, the odds ratio of metachronous lesion was 7.762 compared with the not infected group (95% confidence interval, 1.483-60.854; P = 0.02). In the eradicated group, the odd ratio of metachronous lesion was 8.120 compared with not infected group (95% confidence interval, 1.950-58.985; P = 0.01).

CONCLUSION

Helicobacter pylori infection was an independent risk factor for metachronous gastric lesions. However, eradication of Helicobacter pylori alone does not prevent all metachronous lesions in an inflamed stomach.

Non-microbial approach for Helicobacter pylori as faster track to prevent gastric cancer than simple eradication

Although the International Agency for Research on Cancer declared Helicobacter pylori (H. pylori) as a definite human carcinogen in 1994, the Japanese Society for Helicobacter Research only recently (February 2013) adopted the position that H. pylori infection should be considered as an indication for either amelioration of chronic gastritis or for decreasing gastric cancer mortality. Japanese researchers have found that H. pylori eradication halts progressive mucosal damage and that successful eradication in patients with non-atrophic gastritis most likely prevents subsequent development of gastric cancer. However, those who have already developed atrophic gastritis/gastric atrophy retain potential risk factors for gastric cancer. Because chronic perpetuated progression of H. pylori-associated gastric inflammation is associated with increased morbidity culminating in gastric carcinogenesis, a non-microbial approach to treatment that provides long-term control of gastric inflammation through nutrients and other interventions may be an effective way to decrease this morbidity. This non-microbial approach might represent a new form of prerequisite "rescue" therapy that provides a quicker path to the prevention of gastric cancer as compared to simple eradication.

Variable copy number of mitochondrial DNA (mtDNA) predicts worse prognosis in advanced gastric cancer patients

BACKGROUND

Change of mitochondrial DNA (mtDNA) copy number is widely reported in various human cancers, including gastric cancer, and is considered to be an important hallmark of cancers. However, there is remarkably little consensus on the value of variable mtDNA content in the prognostic evaluation of this cancer.

METHODS

Using real-time quantitative PCR approach, we examined mtDNA copy number in a cohort of gastric cancers and normal gastric tissues, and explored the association of variable mtDNA content with clinical outcomes of gastric cancer patients.

RESULTS

Our data showed that the majority of gastric cancer patients had low mtDNA content as compared to control subjects although the relative mean mtDNA content was higher in the former than the latter. Moreover, we found that variable mtDNA content was strongly associated with lymph node metastasis and cancer-related death of the patients with late-stage tumors. Notably, variable mtDNA content did not affect overall survival of gastric cancer patients, however, we found that increased mtDNA content was associated with poor survival in the patients with late-stage tumors.

CONCLUSION

In this study, we demonstrated that variable mtDNA content markedly increased the risk of lymph node metastasis and high mortality of the patients with late-stage tumors. Additionally, we found a strong link between increased mtDNA content and worse survival of the patients with late-stage tumors. Taken together, variable mtDNA content may be a valuable poor prognostic factor for advanced gastric cancer patients.

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