Systematic review: the chemoprevention of oesophageal adenocarcinoma

Repurposing quinacrine for treatment-refractory cancer

Quinacrine, also known as mepacrine, has originally been used as an antimalarial drug for close to a century, but was recently rediscovered as an anticancer agent. The mechanisms of anticancer effects of quinacrine are not well understood. The anticancer potential of quinacrine was discovered in a screen for small molecule activators of p53, and was specifically shown to inhibit NFκB suppression of p53. However, quinacrine can cause cell death in cells that lack p53 or have p53 mutations, which is a common occurrence in many malignant tumors including high grade serous ovarian cancer. Recent reports suggest quinacrine may inhibit cancer cell growth through multiple mechanisms including regulating autophagy, FACT (facilitates chromatin transcription) chromatin trapping, and the DNA repair process. Additional reports also suggest quinacrine is effective against chemoresistant gynecologic cancer. In this review, we discuss anticancer effects of quinacrine and potential mechanisms of action with a specific focus on gynecologic and breast cancer where treatment-refractory tumors are associated with increased mortality rates. Repurposing quinacrine as an anticancer agent appears to be a promising strategy based on its ability to target multiple pathways, its selectivity against cancer cells, and the synergistic cytotoxicity when combined with other anticancer agents with limited side effects and good tolerability profile.

Maintenance proton pump inhibition therapy and risk of oesophageal cancer

BACKGROUND

The association of long-term use of proton pump inhibitors (PPIs) with oesophageal adenocarcinoma has been poorly defined. Our aim was to assess the risk of oesophageal cancer assessing confounding by indication.

METHODS

This population-based cohort study included all 796,492 adults exposed to maintenance therapy with PPIs in Sweden in 2005-2012. Standardised incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated to assess the risk of oesophageal adenocarcinoma (and squamous cell carcinoma as a comparison) among long-term PPI users relative to the corresponding background population. The different indications for maintenance PPI therapy were analysed separately.

RESULTS

Among all individuals using maintenance PPI therapy, the overall SIR of oesophageal adenocarcinoma was 3.93 (95% CI 3.63-4.24). The SIRs of adenocarcinoma were increased also among individuals without gastro-oesophageal reflux disease who used PPIs for indications not associated with any increased risk of oesophageal adenocarcinoma. For example, the SIRs among participants using maintenance PPI therapy because of maintenance treatment with non-steroidal anti-inflammatory drugs and aspirin were 2.74 (95% CI 1.96-3.71) and 2.06 (95% CI 1.60-2.60), respectively. The SIRs of oesophageal squamous cell carcinoma were increased for most investigated indications, but to a lesser degree than for oesophageal adenocarcinoma.

CONCLUSION

In conclusion, the long term use of PPIs is associated with increased risk of oesophageal adenocarcinoma in the absence of other risk factors. Long term use of PPIs should be addressed with caution.

Quantitation of spatial and temporal variability of biomarkers for Barrett's Esophagus

Chemoprevention and risk-stratification studies in Barrett's esophagus (BE) rely on biomarkers but the variability in their temporal and spatial expression is unknown. If such variability exists, it will impact sampling techniques and sample size calculations. Specimens from three levels of biopsies over two serial endoscopies in nondysplastic BE patients were analyzed for aneuploidy, proliferation markers (Ki67, Mcm2), and cell cycle markers (cyclin A and cyclin D1). A modification of the image cytometry technique, where cytokeratin staining automatically distinguished epithelial and stromal cells, measured aneuploidy on whole tissue sections. Other biomarkers were studied by immunohistochemistry. Coefficient of variability (SD/mean) was calculated; a value <10% indicated low variability. A total of 120 specimens (20 subjects each with three biopsy levels at two time points) from nondysplastic BE patients (71 ± 8.8 years, all Caucasian, 90% males, C5.1M7.5 ± 3.4 cm) were analyzed. The mean interval between endoscopies was 32.8 ± 8.4 months. Aneuploidy had a spatial variability of 6.8% at visit 1 (mean diploid index: 1.1 ± 0.09) and 7.9% at visit 2 (mean diploid index: 1.1 ± 0.06) and a temporal variability of 7.0-8.1% for the three levels. For other biomarkers, the spatial variability ranged from ∼5 to 30% at visit 1 and 11-92% at visit 2 and the temporal variability ranged from 0 to 77%. To conclude, of all the biomarkers, only aneuploidy had both spatial and temporal variability of <10%. Spatial and temporal variability were biomarker dependent and could be as high as 90% even without progression. These data will be useful to design chemoprevention and risk-stratification studies in BE.

Dietary flavonoid intake and Barrett's esophagus in western Washington State

PURPOSE

Flavonoids, concentrated in fruits and vegetables, demonstrate in experimental studies chemopreventive properties in relation to Barrett's esophagus (BE), a precursor lesion for esophageal adenocarcinoma. One case-control investigation reported an inverse association between isoflavone intake and odds of BE, yet no epidemiologic study has considered other flavonoid classes, which are more commonly consumed by Americans.

METHODS

We examined intake of total flavonoids, six flavonoid classes, and lignans among case-control study participants in western Washington State. Food frequency questionnaires were self-completed by BE cases with specialized intestinal metaplasia (n = 170) and matched controls (n = 183).

RESULTS

In logistic regression models adjusted for age, sex, body mass index, and energy intake, the odds ratio (OR) for specialized intestinal metaplasia BE associated with anthocyanidin intake was 0.49 (95% confidence interval: 0.30-0.80, for quartiles 2-4 combined vs. quartile 1), for which wine and fruit juice were major dietary sources. More moderate decreased ORs were noted for flavanones, flavonols, isoflavones, and lignans. A modest increased OR was observed for flavones, for which pizza was the main dietary source in our population.

CONCLUSIONS

Our findings of an inverse association between anthocyanidins and odds of BE suggest that adequate dietary intake of these compounds may lower risk of this cancer precursor lesion.

Omega-3 polyunsaturated Fatty acids as potential chemopreventive agent for gastrointestinal cancer

Omega-3 polyunsaturated fatty acids (n-3 PUFAs), particularly eicosapentanoic acid (EPA) and docosahexanoic acid (DHA), has been acknowledged as essential very long-chain fatty acids contributing to either achieving optimal health or protection against diseases, and even longevity. Recent high impact studies dealing with EPA and DHA have sparked a renewed interest in using n-3 PUFAs for cancer prevention and cancer treatment, for which n-3 PUFAs may exert their anticancer actions by influencing multiple targets implicated in various stages of cancer development, including cell proliferation, cell survival, angiogenesis, inflammation, and metastasis against various cancers. However, gastrointestinal cancers develop implicated with the close connection between inflammation and cancer and n-3 PUFAs especially imposed excellent actions of antiinflammation and antioxidation as well as their restorative actions. In detail, these beneficial lipids can restore or modify inflammation-associated lipid distorsion and alteration of lipid rafts. Although the chemopreventive effect of n-3 PUFAs has been studied in various experimental models, our understanding regarding the underlying mechanisms of n-3 PUFAs against GI cancer is still limited. In this review article, we described the in-detailed perspective and underlying mechanism of n-3 PUFAs application for GI cancers and added in vivo efficacy of n-3 PUFAs with Fat-1 transgenic mice experience. We suggest that future work should consider the n-6/n-3 FA ratio, combination treatment of other nutritions and alteration of lipid rafts to be a key element in experimental design and analysis.

Procyanidin induces apoptosis of esophageal adenocarcinoma cells via JNK activation of c-Jun

Procyanidins are polymeric flavanols found in fruits and vegetables and have shown anticarcinogenic/chemopreventive properties. We previously showed that oligomeric procyanidin extracted from apples induced cell cycle arrest and apoptosis in esophageal adenocarcinoma (OA) cells. To understand the mechanism of action, we determined transcriptomic changes induced by procyanidin in OA cells. Pathway analysis implicated mitogen-activated protein kinase signaling pathways in eliciting these responses. Procyanidin induced the activation of JNK and p38 and the phosphorylation and expression of c-Jun. Inhibition of JNK but not p38 kinase activity prevented the procyanidin-induced phosphorylation and expression of c-Jun. Knockdown of the expression of JNK1, JNK2, or JUN diminished procyanidin-induced effects on cell proliferation and apoptosis. c-Jun is a component of the transcription factor AP-1 and AP-1 binding sites are overrepresented in the promoters of procyanidin-induced genes. This indicates that JNK activation of c-Jun by procyanidin leads to the induction of apoptosis of OA cells and suggests a role for a c-Jun-mediated transcriptional program. These data provide a mechanistic understanding of how procyanidin specifically targets a distinct pathway involved in the induction of apoptosis in OA cells and will inform future studies investigating its use as a chemopreventive/therapeutic agent.

Statins and aspirin for chemoprevention in Barrett's esophagus: results of a cost-effectiveness analysis

Data suggest that aspirin, statins, or a combination of the two drugs may lower the progression of Barrett's esophagus to esophageal adenocarcinoma. However, aspirin is associated with potential complications such as gastrointestinal bleeding and hemorrhagic stroke, and statins are associated with myopathy. We developed a simulation disease model to study the effectiveness and cost effectiveness of aspirin and statin chemoprevention against esophageal adenocarcinoma. A decision analytic Markov model was constructed to compare four strategies for Barrett's esophagus management; all regimens included standard endoscopic surveillance regimens: (i) endoscopic surveillance alone, (ii) aspirin therapy, (iii) statin therapy, and (iv) combination therapy of aspirin and statin. Endpoints evaluated were life expectancy, quality-adjusted life years (QALY), costs, and incremental cost-effectiveness ratios (ICER). Sensitivity analysis was performed to determine the impact of model input uncertainty on results. Assuming an annual progression rate of 0.33% per year from Barrett's esophagus to esophageal adenocarcinoma, aspirin therapy was more effective and cost less than (dominated) endoscopic surveillance alone. When combination therapy was compared with aspirin therapy, the ICER was $158,000/QALY, which was above our willingness-to-pay threshold of $100,000/QALY. Statin therapy was dominated by combination therapy. When higher annual cancer progression rates were assumed in the model (0.5% per year), combination therapy was cost-effective compared with aspirin therapy, producing an ICER of $96,000/QALY. In conclusion, aspirin chemoprevention was both more effective and cost less than endoscopic surveillance alone. Combination therapy using both aspirin and statin is expensive but could be cost-effective in patients at higher risk of progression to esophageal adenocarcinoma.

Risk factors in the development of esophageal adenocarcinoma

OBJECTIVES

It is assumed that esophageal adenocarcinoma is the end result of a stepwise disease process that transitions through gastroesophageal reflux disease (GERD) and Barrett's esophagus. The aim of this study was to examine at what stage known risk factors exert their influence toward the progression to cancer.

METHODS

We enrolled 113 consecutive outpatients without GERD, 188 with GERD, 162 with Barrett's esophagus, and 100 with esophageal adenocarcinoma or high-grade dysplasia (HGD). All patients underwent a standard upper endoscopy and completed a standardized questionnaire about their social history, symptoms, dietary habits, and prescribed medications. We used adjusted logistic regression analysis to assess risk factors between each two consecutive disease stages from the absence of reflux disease to esophageal adenocarcinoma.

RESULTS

Overall, male gender, smoking, increased body mass index (BMI), low fruit and vegetable intake, duration of reflux symptoms, and presence of a hiatal hernia were risk factors for cancer/HGD. However, different combinations of risk factors were associated with different disease stages. Hiatal hernia was the only risk factor to be strongly associated with the development of GERD. For GERD patients, male gender, age, an increased BMI, duration of reflux symptoms, and presence of a hiatal hernia were all associated with the development of Barrett's esophagus. Finally, the development of cancer/HGD among patients with Barrett's esophagus was associated with male gender, smoking, decreased fruit and vegetable intake, and a long segment of Barrett's esophagus, but not with age, BMI, or a hiatal hernia.

CONCLUSIONS

While some risk factors act predominantly on the initial development of reflux disease, others appear to be primarily responsible for the development of more advanced disease stages.

Nonsteroidal anti-inflammatory drugs and statins have chemopreventative effects in patients with Barrett's esophagus

BACKGROUND & AIMS

The incidence of Barrett's esophagus and esophageal adenocarcinoma has increased despite surveillance of patients with Barrett's esophagus. Limited data indicate that nonsteroidal anti-inflammatory drug (NSAID) and statin use reduce the risk for esophageal adenocarcinoma. We investigated whether NSAID or statin use reduces the risk of neoplastic progression from Barrett's esophagus.

METHODS

We performed a prospective study of 570 patients with Barrett's esophagus at 3 academic and 12 regional Dutch hospitals. Information on medication use was collected in patient interviews at each surveillance visit and cross-checked with pharmacy records. Patients completed a questionnaire about use of over-the-counter medication. Incident cases of high-grade dysplasia and adenocarcinoma were identified during the follow-up period.

RESULTS

During a median follow-up period of 4.5 years, 38 patients (7%) developed high-grade dysplasia or adenocarcinoma. After Barrett's esophagus had been diagnosed, 318 patients (56%) used NSAIDs for a median duration of 2 months, 161 (28%) used aspirin for a median duration of 5 years, 209 (37%) used statins for a median duration of 5 years, and 107 (19%) used NSAIDs and statins. NSAID and statin use were each associated with a reduced risk of neoplastic progression (hazard ratio [HR], 0.47; P = .030 and HR, 0.46; P = .048, respectively). Use of a combination of NSAIDs and statins increased the protective effect (HR, 0.22; P = .028).

CONCLUSIONS

NSAID and statin use reduce the risk of neoplastic progression in patients with Barrett's esophagus. Use of a combination of NSAIDs and statins appears to have an additive protective effect.

Beyond DNA binding - a review of the potential mechanisms mediating quinacrine's therapeutic activities in parasitic infections, inflammation, and cancers

This is an in-depth review of the history of quinacrine as well as its pharmacokinetic properties and established record of safety as an FDA-approved drug. The potential uses of quinacrine as an anti-cancer agent are discussed with particular attention to its actions on nuclear proteins, the arachidonic acid pathway, and multi-drug resistance, as well as its actions on signaling proteins in the cytoplasm. In particular, quinacrine's role on the NF-κB, p53, and AKT pathways are summarized.

Epidemiology of adenocarcinoma of the esophagus, gastric cardia, and upper gastric third

The incidence of adenocarcinoma of the esophagus and esophagogastric junction (gastric cardia) has risen rapidly over the past three decades in the United States and northern Europe. This increase had been most dramatic among White males. The majority of these cancers arise from Barrett's esophagus. However, less than 10% of the patients with esophageal adenocarcinoma were known to have Barrett's esophagus before. Current evidence indicates that gastroesophageal reflux and obesity are major risk factors for adenocarcinoma of the esophagus. Abdominal obesity, more prevalent in males, and independent of body mass index, seems to be associated with an increased risk of esophageal adenocarcinoma but not of cardia adenocarcinoma. This observation may explain the high male:female ratio observed in esophageal adenocarcinoma. Tobacco use has also been found as a possible risk factor for adenocarcinoma of the esophagus and gastric cardia. Infection with Helicobacter pylori and the use of nonsteroidal anti-inflammatory drugs might reduce the risk. On the other hand, low intake of fruits, vegetables, and cereal fibers seem to increase the risk of esophageal adenocarcinoma. Currently, there is no evidence that strongly supports any specific strategy to screen a subgroup of the population at risk for adenocarcinoma of the esophagus or esophagogastric junction. Future strategies to decrease obesity and tobacco use might help to reduce the burden of esophageal adenocarcinoma at least partially.

Predictors of progression in Barrett's esophagus: current knowledge and future directions

Barrett's esophagus (BE) is the strongest risk factor for esophageal adenocarcinoma (EAC), a malignancy with persistently poor long-term outcomes. EAC is thought to develop through progression of metaplasia to dysplasia to invasive carcinoma. Identification of factors predicting progression to EAC would help in focusing surveillance, chemoprevention, or ablation for those deemed to be at highest risk of progression. We performed a comprehensive review of the literature and summarized current evidence on risk factors for progression in subjects with known BE. Clinical and demographic factors (age, male gender, length of BE segment) are associated with modestly increased odds of progression to EAC in some studies. Biomarkers such as aneuploidy and p53 loss of heterozygosity have been associated with increased risk of progression to high-grade dysplasia and/or EAC in single-center prospective cohort studies. Promising newer techniques and markers have been recently reported with the potential to help risk stratify BE subjects. Development of a comprehensive BE risk progression score comprised of both clinical and biomarker variables should be the ultimate goal and can be achieved by multicenter prospective collaborative efforts. Although it would be challenging, creation of such a score has the potential to improve outcomes and make the management of patients with BE more cost-effective.

[Gastro-esophageal reflux through gastric antisecretory drugs]

During the 20th century, gastro-esophageal reflux moved from the status of a rare and severe disease to that of a frequent disease occurring mostly, in the absence of any significant lesions. Proton pump inhibitors (PPIs) are the mainstay of its therapy and are prescribed mainly in an empirical way. Extradigestive manifestations require more accurate diagnostic tests and therapeutic management. The modalities of prescription of the PPIs quickly progressed toward the on-demand therapy and over-the-counter PPIs should become widespread. The relative failures of PPIs led to a profusion of new antisecretory agents but clinical improvements are presently disappointing and the rationale of this escalation is questionable. The concept of non acid gastro-esophageal reflux opens more innovative diagnostic and therapeutic perspectives which, however, must be validated. In this respect, endoscopic treatment needs more reliable techniques and more rigorous trials. Gastro-esophageal reflux refractory to PPIs corresponds mainly to functional esophageal disorders that need diagnostic and therapeutic improvements. Barrett's esophagus constitutes a major challenge for the next few years. Its screening and its prevention seem, for the moment, inaccessible. Its survey and the prevention of its complications should benefit from progress of diagnostic and interventional endoscopy.

Procyanidin effects on oesophageal adenocarcinoma cells strongly depend on flavan-3-ol degree of polymerization

Epidemiological studies have shown that the risk of developing oesophageal adenocarcinoma (OA) is inversely correlated to consumption of fruits and vegetables. Flavan-3-ols are the most abundant subclass of flavonoids in these types of foods. Three apple-derived procyanidin fractions with different average degrees of polymerization (aDP) were characterized and the effects of these fractions and of pure flavan-3-ol monomers ((-)-epicatechin and (+)-catechin) and dimers (B1, B2) on two OA cell lines were investigated. Flavan-3-ol monomers and dimers had no effect on the two cell lines, while apple-derived flavan-3-ol oligomers and polymers induced a time-dependent reduction of cell viability. The reduction in the cell viability was due to the induction of caspase-mediated apoptosis and an arrest of the cell cycle in G0/G1. The magnitude of the reduction in cell viability and induction of apoptosis after exposure to flavan-3-ol oligomeric/polymeric fractions positively correlated with their aDP. These results indicate that only flavan-3-ol oligomers and polymers, but not monomers and dimers, have an effect on the proliferation of OA cells in vitro. As tested flavan-3-ol concentrations are achievable through diet, this study suggests that apple-derived PA may possess chemotherapeutic effects against OA.

Systematic review: primary and secondary prevention of gastrointestinal cancers with antioxidant supplements

BACKGROUND

The evidence on whether antioxidant supplements prevent gastrointestinal cancers is contradictory.

AIM

To assess the beneficial and harmful effects of antioxidant supplements in preventing gastrointestinal cancers.

METHODS

Using the Cochrane Collaboration methodology, we reviewed the randomized trials comparing antioxidant supplements with placebo or no intervention on the occurrence of gastrointestinal cancers. We searched electronic databases and reference lists until October, 2007. Our outcome measures were gastrointestinal cancers, overall mortality and adverse events. Outcomes were reported as relative risks (RR) with 95% confidence intervals (CI) based on random-effects and fixed-effect models meta-analyses.

RESULTS

We identified 20 randomized trials (211,818 participants) assessing beta-carotene, vitamin A, vitamin C, vitamin E, and selenium. The trial quality was generally high. The antioxidant supplements were without a significant effect on the occurrence of gastrointestinal cancers (RR 0.94, 95% CI 0.83-1.06, I(2) = 54.0%). The heterogeneity seemed to be explained by bias risk (low-bias risk trials RR 1.04, 95% CI 0.96-1.13 compared to high-bias risk trials RR 0.59, 95% CI 0.43-0.80, test of interaction P < 0.0005) and type of antioxidant supplement (beta-carotene potentially increasing and selenium potentially decreasing cancer risk). Antioxidant supplements had no significant effect on mortality in a random-effects model meta-analysis (RR 1.02, 95% CI 0.97-1.07, I(2) = 53.5%) but significantly increased mortality in a fixed-effect model meta-analysis (RR 1.04, 95% CI 1.02-1.07).

CONCLUSIONS

We could not find evidence that the studied antioxidant supplements prevented gastrointestinal cancers. On the contrary, they seem to increase overall mortality.

Antioxidant supplements for preventing gastrointestinal cancers

BACKGROUND

Oxidative stress may cause gastrointestinal cancers. The evidence on whether antioxidant supplements are effective in preventing gastrointestinal cancers is contradictory.

OBJECTIVES

To assess the beneficial and harmful effects of antioxidant supplements in preventing gastrointestinal cancers.

SEARCH STRATEGY

We identified trials through the trials registers of the four Cochrane Review Groups on gastrointestinal diseases, The Cochrane Central Register of Controlled Trials in The Cochrane Library (Issue 2, 2007), MEDLINE, EMBASE, LILACS, SCI-EXPANDED, and The Chinese Biomedical Database from inception to October 2007. We scanned reference lists and contacted pharmaceutical companies.

SELECTION CRITERIA

Randomised trials comparing antioxidant supplements to placebo/no intervention examining occurrence of gastrointestinal cancers.

DATA COLLECTION AND ANALYSIS

Two authors (GB and DN) independently selected trials for inclusion and extracted data. Outcome measures were gastrointestinal cancers, overall mortality, and adverse effects. Outcomes were reported as relative risks (RR) with 95% confidence interval (CI) based on random-effects and fixed-effect model meta-analysis. Meta-regression assessed the effect of covariates across the trials.

MAIN RESULTS

We identified 20 randomised trials (211,818 participants), assessing beta-carotene (12 trials), vitamin A (4 trials), vitamin C (8 trials), vitamin E (10 trials), and selenium (9 trials). Trials quality was generally high. Heterogeneity was low to moderate. Antioxidant supplements were without significant effects on gastrointestinal cancers (RR 0.94, 95% CI 0.83 to 1.06). However, there was significant heterogeneity (I(2) = 54.0%, P = 0.003). The heterogeneity may have been explained by bias risk (low-bias risk trials RR 1.04, 95% CI 0.96 to 1.13 compared to high-bias risk trials RR 0.59, 95% CI 0.43 to 0.80; test of interaction P < 0.0005), and type of antioxidant supplement (beta-carotene potentially increasing and selenium potentially decreasing cancer risk). The antioxidant supplements had no significant effects on mortality in a random-effects model meta-analysis (RR 1.02, 95% CI 0.97 to 1.07, I(2) = 53.5%), but significantly increased mortality in a fixed-effect model meta-analysis (RR 1.04, 95% CI 1.02 to 1.07). Beta-carotene in combination with vitamin A (RR 1.16, 95% CI 1.09 to 1.23) and vitamin E (RR 1.06, 95% CI 1.02 to 1.11) significantly increased mortality. Increased yellowing of the skin and belching were non-serious adverse effects of beta-carotene. In five trials (four with high risk of bias), selenium seemed to show significant beneficial effect on gastrointestinal cancer occurrence (RR 0.59, 95% CI 0.46 to 0.75, I(2) = 0%).

AUTHORS' CONCLUSIONS

We could not find convincing evidence that antioxidant supplements prevent gastrointestinal cancers. On the contrary, antioxidant supplements seem to increase overall mortality. The potential cancer preventive effect of selenium should be tested in adequately conducted randomised trials.

Esophageal adenocarcinoma arising from Barrett's epithelium in Taiwan

The prevalence of Barrett's esophagus (BE) in Eastern countries is rising to match the prevalence in the West. However, a corresponding trend of BE-associated adenocarcinoma has yet to be observed in Asia. Historically, adenocarcinoma complicating BE has been considered a rare event in Taiwan. In the present report, we collected three Taiwanese cases of esophageal adenocarcinoma arising from BE. The first case was a 37-year-old man with an advanced cancer that developed on pre-existing BE after a 3-year interval without endoscopic surveillance. The second case was a 63-year-old man who presented with odynophagia and was found to have an ulcerative tumor centered on the characteristic Barrett's mucosa. The final case was a 44-year-old man who presented with gradual-onset dysphagia and weight loss, without typical reflux symptom. Our report emphasizes the need for an updated epidemiologic study to determine the incidence of BE-associated adenocarcinoma in Taiwan.

[Medicinal prevention of gastrointestinal tumors: aspirin, Helicobacter and more?]

Despite the huge number of drugs on the market and recent advances in pharmacotherapy, only a few substances are available for the prevention of gastrointestinal tumors--most of which are not approved for this indication or not validated in appropriately designed randomized trials. General recommendations include lifestyle modifications such as avoidance of smoking, only moderate consumption of alcohol, regular physical exercise and a nutrition rich in fresh fruits and vegetables with limited meat. A global eradication therapy for Helicobacter pylori would be desirable to prevent gastric carcinoma, but this does not seem feasible from the socio-economic point of view. Therefore, at least patients at high risk should be screened and this pathogen eradicated, preferentially in their youth. Hepatitis B vaccination of newborns to prevent the development of hepatocellular carcinoma has already been established in Germany; a specific antiviral therapy should be offered to all patients with hepatitis B or C infections, taking into consideration the risks associated with this treatment. The use of non-steroidal anti-inflammatory drugs (NSAIDs) to prevent gastrointestinal malignancies cannot generally be recommended and should be restricted to patients at high risk and to clinical studies. However, the appropriate substance, dose and duration of NSAID therapy are still being debated.

Environmental risk factors in the development of adenocarcinoma of the oesophagus or gastric cardia: a cross-sectional study in a Dutch cohort

BACKGROUND

Risk factors for adenocarcinoma of the oesophagus (OAC) and gastric cardia (GCA) are not yet established.

AIM

To compare environmental risk factors between patients with OAC and GCA.

METHODS

One-hundred and twenty-six patients with OAC, 43 with GCA and 57 with squamous cell carcinoma filled out a questionnaire with information on demographic and lifestyle characteristics, physical activity levels, family history, gastro-oesophageal reflux disease symptoms and medication use.

RESULTS

OAC and GCA patients were similar with regard to male predominance and age, alcohol intake and smoking, use of fruits and vegetables, body posture and occupational activities (P > 0.05). GCA patients less often had heartburn compared with OAC patients [odds ratio (OR) 0.5, 95% confidence interval (CI) 0.2-0.96] and had these symptoms less frequently and for a shorter period (OR 0.3, CI 0.1-1.0 and OR 0.1, CI 0.03-0.6, respectively). Former and current aspirin use was lower among GCA patients than OAC patients (OR 0.2, CI 0.05-0.7 and OR 0.4, CI 0.1-0.9, respectively), whereas no difference in non-steroidal anti-inflammatory drug use was detected.

CONCLUSION

Although OAC and GCA share several environmental risk factors, OAC is more frequently associated with a history of gastro-oesophageal reflux disease, suggesting a more important role for gastro-oesophageal reflux in OAC compared with GCA.

Antioxidant supplements for preventing gastrointestinal cancers

BACKGROUND

Oxidative stress may cause gastrointestinal cancers. The evidence on whether antioxidant supplements are effective in preventing gastrointestinal cancers is contradictory.

OBJECTIVES

To assess the beneficial and harmful effects of antioxidant supplements in preventing gastrointestinal cancers.

SEARCH STRATEGY

We identified trials through the trials registers of the four Cochrane Review Groups on gastrointestinal diseases, The Cochrane Central Register of Controlled Trials on The Cochrane Library (Issue 1, 2003), MEDLINE, EMBASE, LILACS, and SCI-EXPANDED from inception to February 2003, and The Chinese Biomedical Database (March 2003). We scanned reference lists and contacted pharmaceutical companies.

SELECTION CRITERIA

Randomised trials comparing antioxidant supplements to placebo/no intervention examining the incidence of gastrointestinal cancers.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected trials for inclusion and extracted data. The outcome measures were incidence of gastrointestinal cancers, overall mortality, and adverse events. Outcomes were reported as relative risks (RR) with 95% confidence interval (CI) based on fixed and random effects meta-analyses.

MAIN RESULTS

We identified 14 randomised trials (170,525 participants), assessing beta-carotene (9 trials), vitamin A (4 trials), vitamin C (4 trials), vitamin E (5 trials), and selenium (6 trials). Trial quality was generally high. Heterogeneity was low to moderate. Neither the fixed effect (RR 0.96, 95% CI 0.88 to 1.04) nor random effects meta-analyses (RR 0.90, 95% CI 0.77 to 1.05) showed significant effects of supplementation with antioxidants on the incidences of gastrointestinal cancers. Among the seven high-quality trials reporting on mortality (131,727 participants), the fixed effect (RR 1.06, 95% CI 1.02 to 1.10) unlike the random effects meta-analysis (RR 1.06, 95% CI 0.98 to 1.15) showed that antioxidant supplements significantly increased mortality. Two low-quality trials (32,302 participants) found no significant effect of antioxidant supplementation on mortality. The difference between the mortality estimates in high- and low-quality trials was significant by test of interaction (z = 2.10, P = 0.04). Beta-carotene and vitamin A (RR 1.29, 95% CI 1.14 to 1.45) and beta-carotene and vitamin E (RR 1.10, 95% CI 1.01 to 1.20) significantly increased mortality, while beta-carotene alone only tended to do so (RR 1.05, 95% CI 0.99 to 1.11). Increased yellowing of the skin and belching were non-serious adverse effects of beta-carotene. In four trials (three with unclear/inadequate methodology), selenium showed significant beneficial effect on gastrointestinal cancer incidences.

REVIEWERS' CONCLUSIONS

We could not find evidence that antioxidant supplements prevent gastrointestinal cancers. On the contrary, they seem to increase overall mortality. The potential cancer preventive effect of selenium should be studied in adequately conducted randomised trials.