Indomethacin but not a selective cyclooxygenase-2 inhibitor inhibits esophageal adenocarcinogenesis in rats

Cyclooxygenase-1 (COX-1) and COX-1 Inhibitors in Cancer: A Review of Oncology and Medicinal Chemistry Literature

Prostaglandins and thromboxane are lipid signaling molecules deriving from arachidonic acid by the action of the cyclooxygenase isoenzymes COX-1 and COX-2. The role of cyclooxygenases (particularly COX-2) and prostaglandins (particularly PGE₂) in cancer-related inflammation has been extensively investigated. In contrast, COX-1 has received less attention, although its expression increases in several human cancers and a pathogenetic role emerges from experimental models. COX-1 and COX-2 isoforms seem to operate in a coordinate manner in cancer pathophysiology, especially in the tumorigenesis process. However, in some cases, exemplified by the serous ovarian carcinoma, COX-1 plays a pivotal role, suggesting that other histopathological and molecular subtypes of cancer disease could share this feature. Importantly, the analysis of functional implications of COX-1-signaling, as well as of pharmacological action of COX-1-selective inhibitors, should not be restricted to the COX pathway and to the effects of prostaglandins already known for their ability of affecting the tumor phenotype. A knowledge-based choice of the most appropriate tumor cell models, and a major effort in investigating the COX-1 issue in the more general context of arachidonic acid metabolic network by using the systems biology approaches, should be strongly encouraged.

A review of the epidemiology of Barrett's oesophagus and oesophageal adenocarcinoma

While the incidence rates of many cancers have decreased in past decades, the incidence of oesophageal adenocarcinoma continues to increase. The only known precursor for oesophageal adenocarcinoma is Barrett's oesophagus. Studies conducted have identified white race, male sex, GORD, cigarette smoking, obesity, and the absence of Helicobacter pylori status as risk factors for oesophageal adenocarcinoma. Other potential associations include dietary factors and the absence of non-steroidal anti-inflammatory drug use. Many individual studies have been limited by sample size and several meta-analyses have pooled data from studies to address this limitation. In this review we present a synthesis of these studies and summarize current knowledge of risk factors for both oesophageal adenocarcinoma and Barrett's oesophagus.

Aspirin and nonsteroidal anti-inflammatory drug use and the risk of Barrett's esophagus

BACKGROUND

The use of aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) may decrease the risk of esophageal adenocarcinoma; however, it is unknown where these agents may act in the proposed pathway from normal mucosa to Barrett's esophagus to esophageal adenocarcinoma.

AIM

The aim of the study was to evaluate the association between aspirin and NSAID use and Barrett's esophagus in a case-control study within a large community-based population.

METHODS

We conducted a case-control study of aspirin/NSAID use and Barrett's esophagus within the Kaiser Permanente Northern California population. Cases had a new diagnosis of Barrett's esophagus between October 2002 and September 2005; controls were members without a diagnosis of Barrett's esophagus.

RESULTS

Persons with Barrett's esophagus were less likely to use aspirin than population controls [odds ratio (OR) 0.59, 95 % confidence interval (CI) 0.39-0.87]; a stronger association was found among cases and controls with reflux symptoms (OR 0.49, 95 % CI 0.32-0.75; p value interaction = 0.004). Similar associations were found with the use of either aspirin and/or non-aspirin NSAIDs (OR 0.53, 95 % CI 0.35-0.81), although NSAID use alone was not significantly associated with Barrett's esophagus (OR 0.74, 95 % CI 0.47-1.16). The strength of the association was highest among persons with at least moderate-to-high total medication intake.

CONCLUSIONS

Regular use of aspirin or NSAIDs was associated with a decreased risk of Barrett's esophagus, particularly among persons with gastroesophageal reflux disease symptoms. These findings have implications for chemoprevention, as some of the previously described protective association between aspirin/NSAIDs and esophageal adenocarcinoma may be explained by events that occur prior to the development of Barrett's esophagus.

Role of chemoprophylaxis with either NSAIDs or statins in patients with Barrett's esophagus

The incidence of esophageal adenocarcinoma, a poor prognosis neoplasia, has risen dramatically in recent decades. Barrett's esophagus represents the best-known risk factor for esophageal adenocarcinoma development. Non-steroidal anti-inflammatory drugs through cyclooxygenase-2 inhibition and prostaglandin metabolism regulation could control cell proliferation, increase cell apoptosis and regulate the expression of growth and angiogenic factors. Statins can achieve equivalent effects through prenylation and subsequently control of cellular signaling cascades. At present, epidemiological studies are small and underpowered. Their data could not justify either medication as a chemo-preventive agent. Population based studies have shown a 43% reduction of the odds of developing an esophageal adenocarcinoma, leaving out or stating a 25% reduction in patients consuming non-aspirin nonsteroidal anti-inflammatory drugs and a 50% reduction in those patients consuming aspirin. They have also stated a 19% reduction of esophageal cancer incidence when statins have been used. Observational studies have shown that non-steroidal anti-inflammatory drugs could reduce the adenocarcinoma incidence in patients with Barrett's esophagus by 41%, while statins could reduce the risk by 43%. The cancer preventive effect has been enhanced in those patients taking a combination of non-steroidal anti-inflammatory drugs and statins (a 74% decrease). Observational data are equivocal concerning the efficacy of non-steroidal anti-inflammatory drug subclasses. Non-steroidal anti-inflammatory drugs clearly have substantial potential for toxicity, while statins are rather safe drugs. In conclusion, both non-steroidal anti-inflammatory drugs and statins are promising chemopreventive agents and deserve further exploration with interventional studies. In the meanwhile, their use is justified only in patients with cardiovascular disease.