Aspirin and nonsteroidal anti-inflammatory agents and risk for colorectal adenomas

Timing of Aspirin Use in Colorectal Cancer Chemoprevention: A Prospective Cohort Study

BACKGROUND

Prior epidemiological and intervention studies have not been able to separate independent effects of dose, timing, and duration of aspirin use in colorectal cancer (CRC) chemoprevention. We examined aspirin-based CRC chemoprevention according to timing in the Nurses' Health Study and Health Professionals Follow-Up Study.

METHODS

The exposures include cumulative average dose and total duration of aspirin use in more than 10 years before follow-up started (remote period) and in the immediate 10 years before follow-up started (recent period). Cox models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for exposures and CRC risk.

RESULTS

Aspirin use of longer than 10 years before follow-up started (HR = 0.88, 95% CI = 0.83 to 0.94) per 5-year increment and the immediate 10 years before follow-up started (HR = 0.90, 95% CI = 0.84 to 0.96) were similarly important in CRC chemoprevention, though a 5-year lag was required for a clear benefit in the recent period. In the remote period, the association was not dose dependent; compared with less than 0.5 standard-dose (325 mg) tablets per week; hazard ratios were 0.78 (95% CI = 0.63 to 0.98), 0.81 (95% CI = 0.72 to 0.91), and 0.74 (95% CI = 0.64 to 0.86) for doses of 0.5 to less than 1.5, 1.5 to less than 5, and 5 and more tablets per week, respectively. However, there was dose dependency in the recent period (with respective HR = 0.91, 95% CI = 0.79 to 1.06; HR = 0.87, 95% CI = 0.77 to 0.98; and HR = 0.76, 95% CI = 0.64 to 0.91).

CONCLUSIONS

A suggestive benefit necessitates at least 6-10 years and most clearly after approximately 10 years since initiation of aspirin. Remote use and use within the previous 10 years both contribute independently to decrease risk, though a lower dose may be required for a benefit with longer term use.

Mechanism of Apoptosis Induced by Curcumin in Colorectal Cancer

Colorectal cancer (CRC) is among the top three cancer with higher incident and mortality rate worldwide. It is estimated that about over than 1.1 million of death and 2.2 million new cases by the year 2030. The current treatment modalities with the usage of chemo drugs such as FOLFOX and FOLFIRI, surgery and radiotherapy, which are usually accompanied with major side effects, are rarely cured along with poor survival rate and at higher recurrence outcome. This trigger the needs of exploring new natural compounds with anti-cancer properties which possess fewer side effects. Curcumin, a common spice used in ancient medicine was found to induce apoptosis by targeting various molecules and signaling pathways involved in CRC. Disruption of the homeostatic balance between cell proliferation and apoptosis could be one of the promoting factors in colorectal cancer progression. In this review, we describe the current knowledge of apoptosis regulation by curcumin in CRC with regard to molecular targets and associated signaling pathways.

Effects of aspirin on proliferation, invasion and apoptosis of Hep-2 cells via the PTEN/AKT/NF-κB/survivin signaling pathway

Aspirin may exhibit antitumor activities, as it is able to inhibit cell proliferation. However, the ability of aspirin to inhibit cellular proliferation in Hep-2 cells and its underlying molecular mechanisms have been poorly determined. The aim of the present study was to investigate whether aspirin may induce cell apoptosis in the neoplastic cell line Hep-2. The effects of aspirin on the migratory and invasive abilities of Hep-2 cells were also investigated using Transwell assays. In the present study, it was demonstrated that aspirin induced apoptosis and inhibited proliferation, migration and invasion in Hep-2 cells. Aspirin also significantly decreased the expression of B-cell lymphoma 2 (Bcl-2) and caspase-3, and increased the expression of Bcl-2-associated X protein, suggesting that aspirin induced apoptosis through the intrinsic apoptotic pathway. Hep-2 cells treated with aspirin exhibited a significant upregulation of phosphatase and tensin homolog (PTEN) and decreased levels of phosphorylated protein kinase B (AKT). However, the total amount of AKT protein was not altered in response to aspirin treatment. Furthermore, the expression of nuclear factor (NF)-κB and survivin, which are the downstream targets of the PTEN/AKT signaling pathway, was inhibited. These results indicated that the molecular mechanism underlying the antitumor effects of aspirin may be associated with the inhibition of tumor invasion and induction of apoptosis by regulating the activity of the PTEN/AKT/NF-κB/survivin signaling pathway.

Efficacy and safety of celecoxib monotherapy for mild to moderate depression in patients with colorectal cancer: A randomized double-blind, placebo controlled trial

Cancer-related inflammation is an essential process in malignancies. Celecoxib, a nonsteroidal anti-inflammatory drug that acts via the selective inhibition of cyclooxygenase (COX)-2, has shown favorable effects in several psychiatric disorders. The present study aimed to assess the safety and efficacy of celecoxib single therapy on depressive symptoms of patients with colorectal cancer who underwent chemotherapy. The study was conducted as a 6-week, parallel-group, randomized, double-blind, placebo-controlled trial. Forty participants randomly received either 400mg/day celecoxib or placebo. Treatment effect was assessed using the Hamilton Depression Rating Scale (HDRS) and Visual Analogue Scale (VAS) score at baseline and at week 2, 4 and 6 of the trial. Over 6 weeks, patients who received celecoxib showed significant improvement in scores of the Hamilton Depression rating Scale (P=0.003). When comparing the Mean Difference (95% CI) between the two groups of therapy, the celecoxib group demonstrated greater reduction in HDRS score during the study period at weeks 4 (1.95, 95% CI 0.27-3.63, P value =0.024) and 6 (2.60, 95% CI 0.96-4.23, P=0.003). This study indicates celecoxib as a potential monotherapy treatment strategy for mild to moderate depression in patients with colorectal cancer who underwent chemotherapy.

Beclin 1 acetylation impairs the anticancer effect of aspirin in colorectal cancer cells

Regular use of aspirin can reduce cancer incidence, recurrence, metastasis and cancer-related mortality. Aspirin suppresses proliferation and induces apoptosis and autophagy in colorectal cancer cells, but the precise mechanism is not clear. In this study, we demonstrated that aspirin induced autophagosome formation in colorectal cancer cells, but autophagic degradation was blocked through aspirin-mediated Beclin 1 acetylation. Blocked autophagic degradation weakened aspirin-induced cell death. Collectively, our findings indicate the dual roles of aspirin on autophagy, and demonstrate a new mechanism by which Beclin 1 acetylation impairs the anticancer effect of aspirin in colorectal cancer cells.

Aspirin Prevention of Colorectal Cancer: Focus on NF-κB Signalling and the Nucleolus

Overwhelming evidence indicates that aspirin and related non-steroidal anti-inflammatory drugs (NSAIDs) have anti-tumour activity and the potential to prevent cancer, particularly colorectal cancer. However, the mechanisms underlying this effect remain hypothetical. Dysregulation of the nuclear factor-kappaB (NF-κB) transcription factor is a common event in many cancer types which contributes to tumour initiation and progression by driving expression of pro-proliferative/anti-apoptotic genes. In this review, we will focus on the current knowledge regarding NSAID effects on the NF-κB signalling pathway in pre-cancerous and cancerous lesions, and the evidence that these effects contribute to the anti-tumour activity of the agents. The nuclear organelle, the nucleolus, is emerging as a central regulator of transcription factor activity and cell growth and death. Nucleolar function is dysregulated in the majority of cancers which promotes cancer growth through direct and indirect mechanisms. Hence, this organelle is emerging as a promising target for novel therapeutic agents. Here, we will also discuss evidence for crosstalk between the NF-κB pathway and nucleoli, the role that this cross-talk has in the anti-tumour effects of NSAIDs and ways forward to exploit this crosstalk for therapeutic purpose.

Use of NSAIDs for the Chemoprevention of Colorectal Cancer

OBJECTIVE:

To discuss the role of nonsteroidal antiinflammatory drugs (NSAIDs) in the chemoprevention of colorectal cancer.

DATA SOURCES:

A MEDLINE search (1966–May 2003) was performed to identify key literature. Search items included, but were not limited to, NSAIDs, colorectal cancer, chemoprevention, cyclooxygenase-2 (COX-2)–specific inhibitors, and familial adenomatous polyposis (FAP).

STUDY SELECTION AND DATA EXTRACTION:

The search included experimental (in vitro and animal models) and clinical studies evaluating the use of NSAIDs for the chemoprevention of colorectal cancer. The MEDLINE search was supplemented by references from selected articles.

DATA SYNTHESIS:

Numerous experimental, epidemiologic, and clinical studies suggest that NSAIDs have promise as anticancer agents. The mechanism by which NSAIDs lead to decreased colon carcinogenesis is not fully understood, but may involve restoration of apoptosis and inhibition of prostaglandin-mediated angiogenesis. Compelling evidence from many observational studies has consistently documented a 40–50% reduction in the risk of adenomatous polyps, colorectal cancer incidence, and mortality in patients using NSAIDs. Recent randomized, controlled trials have demonstrated a benefit with aspirin in reducing the rate of development of new or recurrent adenomas in high-risk patients. In addition, randomized studies using sulindac and celecoxib in patients with FAP have documented significant regression of existing adenomatous polyps.

CONCLUSIONS:

Inhibition of COX-2 is an example of a targeted approach to the chemoprevention of colorectal cancer. However, controversy exists about the safety, efficacy, and optimal treatment regimen of NSAIDs as long-term chemopreventive agents in the general population. Ongoing studies in high-risk patients with both selective and nonselective COX inhibitors will provide important information in the area of colorectal chemoprevention, but clinical trials' use of adenomas as surrogate markers for chemoprevention trials makes their application to the general population limited.

A healthy lifestyle index is associated with reduced risk of colorectal adenomatous polyps among non-users of non-steroidal anti-inflammatory drugs

In a Columbia, South Carolina-based case-control study, we developed a healthy lifestyle index from five modifiable lifestyle factors (smoking, alcohol intake, physical activity, diet, and body mass index), and examined the association between this lifestyle index and the risk of colorectal adenomatous polyps (adenoma). Participants were recruited from a local endoscopy center and completed questionnaires related to lifestyle behaviors prior to colonoscopy. We scored responses on each of five lifestyle factors as unhealthy (0 point) or healthy (1 point) based on current evidence and recommendations. We added the five scores to produce a combined lifestyle index for each participant ranging from 0 (least healthy) to 5 (healthiest), which was dichotomized into unhealthy (0-2) and healthy (3-5) lifestyle scores. We used logistic regression to calculate odds ratios (OR) and 95% confidence intervals (CI) for adenoma with adjustment for multiple covariates. We identified 47 adenoma cases and 91 controls. In the main analyses, there was a statistically nonsignificant inverse association between the dichotomous (OR 0.54; 95% CI 0.22, 1.29) and continuous (OR 0.75; 95% CI 0.51, 1.10) lifestyle index and adenoma. Odds of adenoma were significantly modified by the use of non-steroidal anti-inflammatory drugs (NSAIDs) (p(interaction) = 0.04). For participants who reported no use of NSAIDs, those in the healthy lifestyle category had a 72% lower odds of adenoma as compared to those in the unhealthy category (OR 0.28; 95% CI 0.08, 0.98), whereas a one-unit increase in the index significantly reduced odds of adenoma by 53% (OR 0.47; 95% CI 0.26, 0.88). Although these findings should be interpreted cautiously given our small sample size, our results suggest that higher scores from this index are associated with reduced odds of adenomas, especially in non-users of NSAIDs. Lifestyle interventions are required to test this approach as a strategy to prevent colorectal adenomatous polyps.

Chemopreventive effect of nonsteroidal anti-inflammatory drugs on the development of a new colorectal polyp or adenoma in a high-risk population: a meta-analysis

BACKGROUND

Although many experimental, epidemiologic, and clinical studies have suggested that aspirin or other nonsteroidal anti-inflammatory drugs (NSAIDs) are effective in reducing and preventing colorectal adenomas, randomized, controlled trials (RCTs) are still being carried out to obtain statistically reliable results.

OBJECTIVE

The aim of this meta-analysis was to review long-term, prospective RCTs investigating the effect of NSAIDs on the relative risk (RR) for developing ≥1 new colorectal polyp or adenoma in a high-risk population.

METHODS

We conducted a comprehensive search of MEDLINE, PubMed, and other electronic databases (including Inter-Science, Science Direct, Ebsco, Synergy, and Proquest) (key terms: nonsteroidal anti-inflammatory drugs, aspirin, colorectal, and polyps; years: 1974-2004) for English-language articles. Eligible studies were analyzed in terms of demographic data, adverse effects, and effect of NSAIDs on the RRs.

RESULTS

Four long-term, prospective RCTs were used in the statistical analysis. A total of 2069 high-risk patients were enrolled; 1880 patients completed the studies, and 1127 were in active-treatment groups (aspirin 81-325 mg/d or sulindac 150-300 mg/d). Our meta-analysis of these studies revealed that the overall RR for developing ≥ 1 new colorectal polyp or adenoma was significantly reduced by using aspirin or other NSAIDs (RR = 0.809; 95% CI, 0.718-0.912).

CONCLUSIONS

The results of this meta-analysis suggest that regular use of aspirin 81 to 325 mg/d or sulindac 150 to 300 mg/d for ≥1 year was associated with a decrease in the RR for developing ≥ 1 new colorectal polyp or adenoma to 0.80 (95% CI, 0.718-0.912) in patients at high risk.

Aspirin use, 8q24 single nucleotide polymorphism rs6983267, and colorectal cancer according to CTNNB1 alterations

BACKGROUND

Regular aspirin use reduces the risk for colorectal cancer (CRC), possibly through inhibition of WNT/cadherin-associated protein β1 (CTNNB1 or β-catenin) signaling. The single nucleotide polymorphism (SNP) rs6983267 on chromosome 8q24 is a CRC susceptibility locus that affects binding activity of transcription factor 7 like-2 (TCF7L2) to CTNNB1, thereby altering expression of target oncogenes, including MYC.

METHODS

We evaluated regular aspirin use and CRC risk according to genotypes of SNP rs6983267 and CTNNB1 expression status in two prospective case-control studies (840 CRC case patients and 1686 age- and race-matched control subjects) nested within the Nurses' Health Study and the Health Professionals Follow-up Study. We estimated odds ratios (ORs) and 95% confidence intervals (CIs) using unconditional logistic regression models. All statistical tests were two-sided.

RESULTS

A lower risk of CRC was associated with regular aspirin use and the T allele of rs6983267. The effect of aspirin was confined to individuals with protective T allele of rs6983267 (additive matching factors-adjusted OR for T allele = 0.83; 95% CI = 0.74 to 0.94; P trend = .002; P interaction = .01). Additionally, the T allele of rs6983267 was associated with a reduced expression of MYC oncogene (P trend = .03). Moreover, among individuals with protective T allele, the effect of regular aspirin use was limited to those with positive nuclear CTNNB1 expression. In a functional analysis, in vitro treatment of LS174T cells (a cell line heterozygous for rs6983267) with aspirin was statistically significantly associated with higher G/T allelic ratio of TCF7L2 immunoprecipitated DNA (P = .03).

CONCLUSIONS

Our results support an influence of aspirin on WNT/CTNNB1 signaling and suggest that aspirin chemoprevention may be tailored according to rs6983267 genotype.

Aspirin-induced Bcl-2 translocation and its phosphorylation in the nucleus trigger apoptosis in breast cancer cells

Here, we report that B-cell lymphoma 2 (Bcl-2) is a novel target molecule of aspirin in breast cancer cells. Aspirin influenced the formation of a complex by Bcl-2 and FKBP38 and induced the nuclear translocation of Bcl-2 and its phosphorylation. These events inhibited cancer cell proliferation and subsequently enhanced MCF-7 breast cancer cell apoptosis. Bcl-2 knockdown using small interfering RNA (siRNA) delayed apoptotic cell death, which correlated with increased proliferation following aspirin exposure. In contrast, Bcl-2 overexpression enhanced the onset of aspirin-induced apoptosis, which was also associated with a significant increase in Bcl-2 phosphorylation in the nucleus. Therefore, this study may provide novel insight into the molecular mechanism of aspirin, particularly its anticancer effects in Bcl-2- and estrogen receptor-positive breast cancer cells.

Physical activity and other lifestyle factors in relation to the prevalence of colorectal adenoma: a colonoscopy-based study in asymptomatic Koreans

PURPOSE

To evaluate physical activity and other lifestyle risk factors in relation to the prevalence of colorectal adenomas in asymptomatic Koreans.

METHODS

A total of 1,526 asymptomatic subjects who underwent a colonoscopy were enrolled. Lifestyle factors such as physical activity and smoking data were obtained using a questionnaire. The subjects were grouped into three exposure levels by tertiles of metabolic equivalent hours per week. We evaluated the risk factors in subjects with adenomas by risk stratification (low-risk adenoma group vs. high-risk adenoma group) and by anatomic location (proximal colon, distal colon, rectum, and multiple locations). The high-risk adenoma group was defined as subjects with advanced adenomas or multiple (≥ 3) adenomas.

RESULTS

A total of 456 participants had colorectal adenomas, and 861 had no polyps. In multivariate analyses, higher levels of physical activity were associated with a significantly decreased risk of colorectal adenomas (OR = 0.56, 95% CI 0.40-0.79). This inverse association was stronger for the risk of high-risk adenomas (OR = 0.39, 95% CI 0.21-0.73) than for low-risk adenomas (OR = 0.62, 95% CI 0.43-0.89). The negative relation of physical activity was significant for distal colon adenomas (OR = 0.54, 95% CI 0.30-0.95) and the adenomas with multiple locations (OR = 0.39, 95% CI 0.21-0.72).

CONCLUSIONS

Increased physical activity is associated with a reduced prevalence of colorectal adenomas. The inverse association between physical activity and adenoma was stronger for the risk of advanced or multiple adenomas.

Review of the selective COX-2 inhibitors celecoxib and rofecoxib: focus on clinical aspects

The selective cyclooxygenase-2 (COX-2) inhibitors celecoxib and rofecoxib were designed to have similar efficacy but less gastrointestinal toxicity than traditional nonsteroidal anti-inflammatory drugs (NSAIDs). Their efficacy has been demonstrated in the treatment of osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, postoperative dental pain and dysmenorrhea. These agents produce fewer endoscopic ulcers, symptomatic ulcers and gastrointestinal bleeds than traditional NSAIDs; although the absolute benefit is small and the gastropreserving effect is negated by concurrent use of low-dose aspirin for cardiovascular risk reduction. Nephrotoxicity and hyptertension remain concerns with COX-2 inhibitors, as they are with traditional NSAIDs. COX-2 inhibitors may be safe alternatives to traditional NSAIDs for patients with aspirin-sensitive asthma.

Serum salicylate levels and risk of recurrent colorectal adenomas

BACKGROUND

Intake of aspirin is associated with reduction in risk of colorectal adenoma and carcinoma. Some plants contain salicylates, and individuals not taking aspirin may have measurable salicylate levels. However, the association between serum salicylate level and recurrence of adenoma in nonusers of aspirin has not been studied.

METHODS

We measured serum salicylate levels in participants in a randomized controlled trial with calcium supplementation for the prevention of colorectal adenomas. Generalized linear models were used to assess the association between serum levels and adenoma risk during the follow-up period of the trial.

RESULTS

We did not find an association with recurrence of adenomas or advanced adenomas with serum salicylate levels at year 1 among nonusers of aspirin. There was no effect modification of the chemopreventive effect of calcium supplementation in reducing risk of recurrent adenomas or advanced adenomas.

CONCLUSIONS

Among nonusers of ASA, serum salicylate levels are not associated with risk of recurrence of adenomas.

IMPACT

Serum salicylate levels can be detected in individuals not taking aspirin, but the levels may be too low to confer protection from risk of recurrent adenomas.

Blood 25-hydroxyvitamin D3 concentrations and incident sporadic colorectal adenoma risk: a pooled case-control study

The authors examined the association between circulating 25-hydroxyvitamin D(3) (25(OH)D(3)), the best indicator of total vitamin D exposure, and incident, sporadic colorectal adenoma risk in a pooled analysis of primary data from 3 colonoscopy-based case-control studies conducted in Minnesota, North Carolina, and South Carolina between 1991 and 2002. The pooled study included 616 colorectal adenoma cases and 770 polyp-free controls. Multivariable logistic regression was used to estimate the association between circulating 25(OH)D(3) and colorectal adenoma risk. Stratified analyses and the likelihood ratio test were used to examine effect modification by various risk factors. In the pooled analysis, higher circulating 25(OH)D(3) concentrations were statistically significantly associated with decreased colorectal adenoma risk (highest vs. lowest quartile odds ratio = 0.59, 95% confidence interval: 0.41, 0.84). The observed inverse association was stronger among participants who used nonsteroidal antiinflammatory drugs regularly (highest vs. lowest quartile odds ratio = 0.33, 95% confidence interval: 0.19, 0.56). Inverse associations between 25(OH)D(3) and colorectal adenoma did not differ substantially by other risk factors or by adenoma characteristics. These findings support the hypothesis that greater vitamin D exposure may reduce the risk of colorectal adenoma and suggest that it may do so more strongly in combination with antiinflammatory agents.

Primary prevention of colorectal cancer

Colorectal cancer has been strongly associated with a Western lifestyle. In the past several decades, much has been learned about the dietary, lifestyle, and medication risk factors for this malignancy. Although there is controversy about the role of specific nutritional factors, consideration of dietary pattern as a whole appears useful for formulating recommendations. For example, several studies have shown that high intake of red and processed meats, highly refined grains and starches, and sugars is related to increased risk of colorectal cancer. Replacing these factors with poultry, fish, and plant sources as the primary source of protein; unsaturated fats as the primary source of fat; and unrefined grains, legumes and fruits as the primary source of carbohydrates is likely to lower risk of colorectal cancer. Although a role for supplements, including vitamin D, folate, and vitamin B6, remains uncertain, calcium supplementation is likely to be at least modestly beneficial. With respect to lifestyle, compelling evidence indicates that avoidance of smoking and heavy alcohol use, prevention of weight gain, and maintenance of a reasonable level of physical activity are associated with markedly lower risks of colorectal cancer. Medications such as aspirin and nonsteroidal anti-inflammatory drugs and postmenopausal hormones for women are associated with substantial reductions in colorectal cancer risk, though their utility is affected by associated risks. Taken together, modifications in diet and lifestyle should substantially reduce the risk of colorectal cancer and could complement screening in reducing colorectal cancer incidence.

The effect of aspirin in the recurrence of colorectal adenomas: a meta-analysis of randomized controlled trials

PURPOSE

Colorectal adenomas are precursors of most colorectal cancers and are important targets for chemoprevention. Aspirin is thought to play an important role in chemoprevention. However, the role of aspirin in preventing recurrence of adenomas is controversial. We performed a systematic review and meta-analysis to evaluate the effect of aspirin in preventing the recurrence of colorectal adenoma.

METHOD

Trials were located through Medline, Embase and the Cochrane Central Register of Controlled Trials (CENTRAL). From 14 articles screened, three were identified as randomized controlled trials and were included for data extraction. Main outcome measures were the recurrence of any new adenoma and advanced adenoma. The meta-analysis was performed with the fixed-effects model.

RESULTS

A total of 2338 participants were enrolled in the three studies and 2175 of them completed the follow-up colonoscopy. We found that the relative risks of any adenoma (when compared with the placebo group) were 0.859 in the high dose of aspirin groups (95% confidence interval (CI), 0.756-0.976, P = 0.019), 0.826 in the low dose of aspirin groups (95% CI 0.706-0.965, P = 0.016) and 0.836 in the both aspirin combined groups (95% CI 0.746-0.937, P = 0.002). For the recurrence of advanced adenoma, the relative risk (when compared with the placebo group) was 0.655 (95% CI 0.513-0.837, P = 0.001) in the aspirin groups without considering the dose.

CONCLUSION

This meta-analysis suggests that aspirin prevents recurrent colorectal adenomas among patients with a history of colorectal adenomas.

Concept of chemoprevention in colorectal cancer

Colorectal cancer remains a significant cause of morbidity and mortality throughout the world. The incidence of colorectal cancer is nearly four-fold higher in more-developed as compared with less-developed regions of the world. At present an early detection of colorectal cancer remains a crucial step in determining the therapeutic outcomes. Screening programmes have been introduced in an effort to detect colorectal cancer at an early stage or at a precancerous colonic polyp stage. These programmes should be used by the health professionals as an opportunity to educate the public regarding the use of chemoprevention in colorectal cancer, which is the main focus of this review and an attractive concept needing further evaluation.

Use of non-steroidal anti-inflammatory drug and colorectal polyps: a systematic review and Meta-analysis

AIM: The evaluate the association between use of nonsteroidal anti-inflammatory drugs (NSAIDs) and the risk of colorectal polyps.

METHODS: A fully recursive literature search from 1966 to December 2007 was conducted in PubMed, EMBASE, Cancerlit, ISI and Cochrane Collaboration controlled trials register to identify relevant studies. Summary odds ratios (OR) and 95% confidence intervals (CI) were calculated under a random-effects model.

RESULTS: Thirty nine studies (17 controlled clinical trials, 12 case-control and 10 cohort) were identified. The use of NSAIDs was associated with a statistically significant reduction for the recurrence or occurrence of colorectal polyps in patients with sporadic adenomas, with a summary OR of 0.63 (95%CI: 0.53-0.75, P = 0.37) for randomized controlled trials, 0.70 (95%CI: 0.61-0.80, P = 0.02) for case-control studies, and 0.86 (95%CI: 0.77-0.96, P = 0.02) for cohort studies. Seven controlled clinical trials reported a significant regression and a reduction in the number and size of polyps in patients with familial adenomatous polyposis after NSAIDs treatment. As for the type of drugs, the use of aspirin and non-aspirin NSAIDs demonstrated a similar magnitude of risk reduction. A dose-dependent association between NSAIDs use and the risk reduction of colorectal polyps was confirmed in six randomized controlled trials, three case-control and one cohort studies.

CONCLUSION: Use of NSAIDs is associated with a decreased risk of colorectal polyps in a dose-dependent manner. The findings warrant proper clinical trials to define the optimal dose and duration of treatment, and to balance the risks and benefits of prophylactic use of NSAIDs in specific populations.

Apoptosis in normal rectal mucosa, baseline adenoma characteristics, and risk of future adenomas

Low apoptosis in the normal rectal mucosa has been associated with colorectal adenomas in cross-sectional studies. It is unknown whether apoptosis can predict the occurrence of new adenomas. We evaluated whether apoptosis at baseline colonoscopy, as well as patient and adenoma characteristics, could predict future occurrence of adenomas. Study subjects were participants in the Diet and Health Study III, a cross-sectional study of adenoma risk factors between August 1998 and March 2000. At baseline, subjects underwent colonoscopy and provided normal rectal mucosal biopsies to evaluate apoptosis as well as information about diet and lifestyle. The present study includes 257 subjects who returned for follow-up colonoscopy between 2000 and 2005. Apoptosis, number of adenomas, size, and atypia at baseline colonoscopy were evaluated as predictors of new adenomas. Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (95% CI). At baseline, low apoptosis was significantly associated with increased risk of adenomas (P = 0.0001). Compared with those in the lowest tertile, subjects with high apoptosis were less likely to have an adenoma at follow-up (crude OR, 0.25; 95% CI, 0.09-0.65; adjusted OR, 0.29; 95% CI, 0.08-1.06). Having three or more adenomas at baseline was associated with increased risk of new adenomas (crude OR, 2.46; 95% CI, 1.14-5.31; adjusted OR, 3.74; 95% CI, 1.01-13.83). This study suggests that lower apoptosis is associated with increased risk of future adenoma development. If confirmed in larger studies, apoptosis could potentially be used to identify patients at highest risk for developing new adenomas.

Cyclooxygenase in the treatment of glioma: its complex role in signal transduction

BACKGROUND

High-grade glioma remains one of the most difficult cancers to treat. Recent studies in oncology have identified a role of the ubiquitous enzyme, cyclooxygenase (Cox), especially cyclooxygenase-2 (COX-2) in cell proliferation, and its inhibition in cancer control, apoptosis, as well as synergy with other forms of therapy. The inhibitors of the Cox enzyme are well known as members of the nonsteroidal anti-inflammatory drug (NSAID) class of pharmaceuticals.

METHODS

In vitro and in vivo studies of different cancers expressing COX-2, including glioma studies, along with the few clinical trials that have been reported are reviewed to specifically identify the actions of these agents.

RESULTS

The anticancer effect of the COX-2 inhibitors may occur irrelevant of COX-2 expression, and it appears to be drug-specific, as well as dose-specific in different cancers. In combination with chemotherapeutic agents, the COX-2 inhibitors may have an additive, synergistic, or inhibitory effect on tumor growth.

CONCLUSIONS

As evaluations of this class of drugs begin in glioma, in vitro and in vivo data should be acquired to accurately predict which compounds will have an effect in controlling tumor growth and at which doses these should be used. The actual expression and inhibition of COX-2 may not always be relevant to the effects on tumor growth.

[Cyclooxygenase 2 and colorectal cancer: therapeutic implications]

There is epidemiological evidence that suggests an inverse association between the consumption of non-steroidal anti-inflammatories (NSAIDs) and the risk of developing certain neoplasms. This association led to the identification of the therapeutic target of these drugs, cyclooxygenase type 2 (COX-2). Later studies have demonstrated that COX-2 is over-expressed in many malignant and pre-malignant lesions of different origins, among which are included colorectal neoplasms. This factor explains the beneficial effect observed with the use of classic NSAIDs and more recently, with selective COX-2 inhibitors (coxibs), in the treatment and/or prevention of several neoplasms.

Cyclooxygenase-2 (cox-2) and the inflammogenesis of cancer

Cohesive scientific evidence from molecular, animal, and human investigations supports the hypothesis that aberrant induction of COX-2 and up-regulation of the prostaglandin cascade play a significant role in carcinogenesis, and reciprocally, blockade of the process has strong potential for cancer prevention and therapy. Supporting evidence includes the following: [1] expression of constitutive COX-2-catalyzed prostaglandin biosynthesis is induced by most cancer-causing agents including tobacco smoke and its components (polycylic aromatic amines, heterocyclic amines, nitrosamines), essential polyunsaturated fatty acids (unconjugated linoleic acid), mitogens, growth factors, proinflammatory cytokines, microbial agents, tumor promoters, and other epigenetic factors, [2] COX-2 expression is a characteristic feature of all premalignant neoplasms, [3] COX-2 expression is a characteristic feature of all malignant neoplasms, and expression intensifies with stage at detection and cancer progression and metastasis, [4] all essential features of carcinogenesis (mutagenesis, mitogenesis, angiogenesis, reduced apoptosis, metastasis, and immunosuppression) are linked to COX-2-driven prostaglandin (PGE-2) biosynthesis, [5] animal studies show that COX-2 up-regulation (in the absence of genetic mutations) is sufficient to stimulate the transformation of normal cells to invasive cancer and metastatic disease, [6] non-selective COX-2 inhibitors, such as aspirin and ibuprofen, reduce the risk of human cancer and precancerous lesions, and [7] selective COX-2 inhibitors, such as celecoxib, reduce the risk of human cancer and precancerous lesions at all anatomic sites thus far investigated. Results confirming that COX-2 blockade is effective for both cancer prevention and therapy have been tempered by observations that some COX2 inhibitors pose a risk to the cardiovascular system, and more studies are needed in order to determine if certain of these drugs can be taken at dosages that prevent cancer without increasing cardiovascular risk. It is emphasized that the "inflammogenesis model of cancer" is not mutually exclusive and may in fact be synergistic with the accumulation of somatic mutations in tumor suppressor genes and oncogenes or epigenetic factors in the development of cancer.

Nonsteroidal anti-inflammatory drugs and subsite-specific colorectal cancer incidence in the Iowa women's health study

BACKGROUND

Previous epidemiologic studies have shown that regular use of nonsteroidal anti-inflammatory drugs (NSAIDs) is associated with decreased colorectal cancer risk. However, few studies have examined associations between NSAID use and subsite-specific colorectal cancer risks. Because tumors of the proximal and distal colon differ with respect to their genetic alterations, clinicopathologic features, and demographic distribution, further investigation of subsite-specific colorectal cancer risks may be rewarding.

METHODS

Data about aspirin and non-aspirin-NSAID use were recorded by self-report in 1992 among the initially cancer-free cohort of postmenopausal women in the Iowa Women's Health Study (n = 27,160). In total, 637 women developed colorectal cancer during the 11 years of follow-up, including 365 proximal colon, 132 distal colon, and 120 rectal cancer cases (11 overlapping and 9 not specified).

RESULTS

For colon cancer, the multivariable-adjusted hazard ratios (HR) for women reporting use of aspirin two to five times and six or more times weekly (compared with nonusers of aspirin) were 0.79 [95% confidence interval (95% CI), 0.59-1.04] and 0.76 (95% CI, 0.58-1.00), respectively. The corresponding HRs for non-aspirin NSAIDs were 0.63 (95% CI, 0.41-0.96) and 0.85 (95% CI, 0.63-1.15), respectively. For proximal colon cancer, the multivariable-adjusted HRs for women reporting use of aspirin or non-aspirin NSAIDs two or more times weekly (compared with nonusers of each) were 0.67 (95% CI, 0.51-0.87) and 0.71 (95% CI, 0.52-0.97), respectively. No statistically significant association was found between either distal colon or rectal cancer and aspirin or non-aspirin NSAID use.

DISCUSSION

Our study is consistent with a limited number of prior reports that have observed stronger associations between NSAID use and proximal versus distal colorectal cancer.

Association of Aspirin and Nonaspirin Nonsteroidal Anti-inflammatory Drugs With Cancer Incidence and Mortality

BACKGROUND

The cancer chemopreventive benefits of aspirin and nonaspirin nonsteroidal anti-inflammatory drugs (NSAIDs) are incompletely defined and may vary by smoking history. We evaluated associations between aspirin and nonaspirin NSAID use with cancer incidence and mortality stratified by smoking history in the Iowa Women's Health Study, a prospective cohort of postmenopausal women.

METHODS

Aspirin and nonaspirin NSAID use was self-reported by questionnaire in 1992. Cancer incidence and mortality were ascertained by annual linkage to the Iowa Surveillance, Epidemiology, and End Results Cancer Registry and death certificates. Cox proportional hazards models were used to estimate multivariable relative risks (RRs) and 95% confidence intervals (CIs). All statistical tests were two-sided.

RESULTS

During an average of 10 years of follow-up, 3487 incident cancer cases and 3581 deaths were observed in the cohort of 22,507 women. Compared with nonuse, aspirin use was inversely associated with total cancer incidence (multivariable-adjusted RR = 0.84, 95% CI = 0.77 to 0.90), with age-adjusted incidence rates of 147 and 170 per 10,000 person-years for ever and never users, respectively, and was inversely associated with cancer mortality (multivariable-adjusted RR = 0.87, 95% CI = 0.76 to 0.99), with age-adjusted rates of 47 and 52 per 10,000 person-years. The inverse relationship was stronger among former and never smokers than current smokers, although not statistically significantly (P = .28). Aspirin use was also inversely associated with coronary heart disease mortality (multivariable-adjusted RR = 0.75, 95% CI = 0.64 to 0.89), with age-adjusted rates of 23 and 30 per 10,000 person-years for ever and never users, respectively, and with all-cause mortality (multivariable-adjusted RR = 0.82, 95% CI = 0.76 to 0.89), with age-adjusted rates of 126 and 155 per 10,000 person-years. Nonaspirin NSAID use was not associated with cancer incidence or mortality, coronary heart disease mortality, or all-cause mortality.

CONCLUSIONS

Aspirin use, but not nonaspirin NSAID use, was associated with lower risks of cancer incidence and mortality, which was more pronounced among former and never smokers than current smokers.

5-aminosalicylic acid in combination with nimesulide inhibits proliferation of colon carcinoma cells in vitro

AIM: To investigate the effects of 5-aminosalicylic acid (5-ASA) in combination with nimesulide on the proliferation of HT-29 colon carcinoma cells and its potential mechanisms.

METHODS: Inhibitory effects of drugs (5-ASA, nimesulide and their combination) on HT-29 colon carcinoma cells were investigated by thiazolyl blue tetrazolium bromide (MTT) assay. Cellular apoptosis and proliferation were detected by TUNEL assay and immunocytochemical staining, respectively.

RESULTS: Pretreatment with 5-ASA or nimesulide at the concentration of 10-1000 μmol/L inhibited proliferation of HT-29 colon carcinoma cells in a dose-dependent manner in vitro (t = 5.122, P < 0.05; t = 3.086, P < 0.05, respectively). The inhibition rate of HT-29 colon carcinoma cell proliferation was also increased when pretreated with 5-ASA (100 μmol/L) or nimesulide (100 μmol/L) for 12-96 h, which showed an obvious time-effect relationship (t = 6.149, P < 0.05; t = 4.159, P < 0.05, respectively). At the concentration of 10-500 μmol/L, the apoptotic rate of HT-29 colon carcinoma cells significantly increased (t = 18.156, P < 0.001; t = 19.983, P < 0.001, respectively), while expression of proliferating cell nuclear antigen (PCNA) was remarkably decreased (t = 6.828, P < 0.05; t = 14.024, P < 0.05, respectively). 5-ASA in combination with nimesulide suppressed the proliferation of HT-29 colon carcinoma cells more than either of these agents in a dose-dependent and time-dependent manner (t = 5.448, P < 0.05; t = 4.428, P < 0.05, respectively).

CONCLUSION: 5-ASA and nimesulide may inhibit the proliferation of HT-29 colon carcinoma cells and coadministration of these agents may have additional chemopreventive potential.

Polyamine metabolism and cancer prevention

Colorectal cancer is one of a number of cancers that may be amenable to prevention. The NSAIDs (non-steroidal anti-inflammatory drugs) have been shown to be effective chemopreventative agents in humans, but their mechanism of action is not clear. The polyamines are cellular polycations that are essential for cell growth and are overproduced in cancer cells. It is our hypothesis that inhibition of polyamine metabolism is an integral part of the mechanism of cancer prevention mediated by NSAIDs.

Nonsteroidal antiinflammatory drug use and risk of bladder cancer in the health professionals follow-up study

Nonsteroidal antiinflammatory drugs (NSAIDs) use, particularly aspirin, may lower the risk of several cancers, including bladder. NSAIDs may reduce development of bladder tumors by decreasing inflammation, inhibiting cycloxygenase-2, inhibiting proliferation and inducing apoptosis of cancer cells. However, acetaminophen, a major metabolite of phenacetin, may be positively associated with bladder cancer risk. Results from case-control studies on NSAIDs and acetaminophen use and bladder cancer risk are inconsistent. We investigated the association between NSAID and acetaminophen use and bladder cancer risk in a large cohort of US males. Among 49,448 men in the Health Professionals Follow-Up Study, 607 bladder cancer cases were confirmed during 18 years of follow-up. Relative risks (RR) and 95% confidence intervals (CI) were calculated by Cox proportional hazards models. Multivariate RR were adjusted for age, current smoking status, pack years, geographic region and fluid intake. No significant associations were observed for regular aspirin (> or =2 tablets per week), (RR = 0.99, 95% CI 0.83-1.18), ibuprofen (RR = 1.11, 95% CI 0.81-1.54), acetaminophen (RR = 0.96, 95% CI 0.67-1.39) or total NSAID use (not including acetaminophen; RR = 1.01, 95% CI 0.85-1.20) and bladder cancer risk compared with nonuse. Consistent use (over 6 years) of aspirin, ibuprofen, acetaminophen and total NSAIDs, compared to nonuse, was not associated with bladder cancer risk. No association was observed between aspirin frequency and dose and bladder cancer risk. We observed no effect-modification by smoking, age or fluid intake. Our results suggest that regular NSAID or acetaminophen use has no substantial impact on bladder cancer risk among men.

Cancer chemoprevention by cyclooxygenase 2 (COX-2) blockade: results of case control studies

Significant use of selective cyclooxygenase-2 (COX-2) blocking agents prescribed for the treatment of arthritis during 1999 to 2005 facilitates epidemiologic investigations to illuminate their chemopreventive effects against human cancer. We therefore conducted a set of case control studies of selective COX-2 blocking agents to determine their chemopreventive potential for the four major cancers: breast, prostate, colon, and lung. Newly diagnosed cases (323 breast cancer patients, 229 prostate cancer patients, 326 colon cancer patients, and 486 lung cancer patients) were ascertained during 2002 to September 30, 2004, at The James Cancer Hospital and Solove Research Institute, The Ohio State University Medical Center, Columbus, Ohio. All cases of invasive cancer were confirmed by examination of the pathology report. Healthy controls without cancer were ascertained from hospital screening clinics during the same time period. Controls were frequency matched at a rate of 2:1 to the cases by age, gender, and county of residence. We collected information on type, frequency, and duration of use of selective COX-2 inhibitors and nonselective nonsteroidal anti-inflammatory drugs (NSAIDs). Other potentially important risk factors (smoking, drinking, body mass, medical history, blood pressure and cholesterol medications, family history of cancer, occupational history, and reproductive history for women) were also recorded for each subject. Estimates of odds ratios were obtained with adjustment for age and other potential confounders using logistic regression analysis. Use of selective COX-2 inhibitors resulted in a significant risk reduction for each type of cancer (71% for breast cancer, 55% for prostate cancer, 70% for colon cancer, and 79% for lung cancer) and an overall 68% risk reduction for all four cancers. This investigation demonstrates that COX-2 blocking agents have strong potential for the chemoprevention of cancers of the breast, prostate, colon and lung.

The association between aspirin use and the incidence of colorectal cancer in women

The purpose of this study was to test the hypothesis that aspirin use is associated with a decreased risk of incident colorectal cancer. From the Women's Health Initiative, 91,574 participants between the ages of 50 and 79 years at baseline in 1993-1998 provided details on aspirin use via interview using a standardized questionnaire and were subsequently followed annually for incident colorectal cancer during a period of over 6 years. For those persons who reported aspirin use, the type of compound, dose, and duration of use were recorded. Medical histories suggestive of colorectal cancers at the annual update were verified by medical record and pathology report review by trained local physician adjudicators. There were 631 confirmed cases of invasive cancer of the colon or rectum. There was no significant association between any aspirin use and risk for incident colorectal cancer (hazard ratio = 0.96, 95% confidence interval: 0.8, 1.2). Moreover, with no aspirin use as the referent category, there were no significant associations for duration of aspirin intake by category (< 1, 1- < 2, 2- < 3, 3- < 4, 4- < 5, and > or = 5 years) or for daily dosage by category (< 165, 165- < 300, 300- < 495, or > or = 495 mg).

Inflammatory cytokine gene polymorphisms, nonsteroidal anti-inflammatory drug use, and risk of adenoma polyp recurrence in the polyp prevention trial

BACKGROUND

Pro- and anti-inflammatory cytokine genes may be important in the maintenance and progression of colorectal cancer. It is possible that single-nucleotide polymorphisms in inflammatory genes may play a role in chronic colonic inflammation and development of colorectal adenomas. Furthermore, common variants in cytokine genes may modify the anti-inflammatory effect of nonsteroidal anti-inflammatory drugs (NSAIDs) in the prevention of colorectal cancer.

METHODS

We examined the association between cytokine gene polymorphisms and risk of recurrent adenomas among 1,723 participants in the Polyp Prevention Trial. We used logistic regression to calculate odds ratios (OR) for the association between genotype, NSAID use, and risk of adenoma recurrence.

RESULTS

Cytokine gene polymorphisms were not statistically significantly associated with risk of adenoma recurrence in our study. We observed statistically significant interactions between NSAID use, IL-10 -1082 G>A genotype, and risk of adenoma recurrence (P = 0.01) and multiple adenoma recurrence (P = 0.01). Carriers of the IL-10 -1082 G>A variant allele who were non-NSAID users had a statistically significant decreased risk of multiple adenoma recurrence (OR, 0.43; 95% confidence interval, 0.24-0.77) as well as a nonsignificant 30% decreased risk of any adenoma recurrence. In contrast, NSAID users who were carriers of the IL-10 -1082 G>A variant allele were at an increased risk of any adenoma recurrence (OR, 1.55; 95% confidence interval, 1.00-2.43).

CONCLUSION

These findings suggest that individuals who are carriers of the IL-10 -1082 G>A variant allele may not benefit from the chemoprotective effect of NSAIDs on adenoma polyp recurrence.

Hormone replacement therapy, reproductive history, and colorectal adenomas: data from the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial (United States)

OBJECTIVE

Findings from some epidemiologic studies of colorectal cancer and adenoma suggest that the protective effect of post-menopausal hormone replacement therapy (HRT) may differ across categories of age and body mass index (BMI). We conducted an analysis of women participating in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial to investigate the relationship between HRT use and prevalent adenoma, both overall and across different population subgroups.

METHODS

Women aged 55-74 were randomized to screening by flexible sigmoidoscopy at ten PLCO screening centers between September 1993 and September 2001. We identified 1468 women with at least one left-sided adenoma and 19,203 without adenoma or colorectal cancer. Information about HRT and reproductive factors was obtained from a self-administered questionnaire.

RESULTS

Compared to never use of HRT, current use was associated with a decreased prevalence of left-sided adenoma (odds ratio (OR) 0.85; 95% confidence interval (CI) 0.75-0.97). We found no evidence of dose-response with increasing duration of use for current or former users. The association with current HRT use was stronger among women aged 65+ (OR 0.69; 95% CI 0.56-0.84), with a BMI<30 (OR 0.82; 95% CI 0.71-0.95) and who regularly use aspirin or ibuprofen (OR 0.77; 95% CI 0.65-0.91). Other reproductive factors were not significantly associated with adenoma prevalence.

CONCLUSIONS

Our findings suggest that current HRT use may protect against colorectal adenoma, and that this protective effect is short-lived following cessation of use.

Lifestyle-related risk factors and chemoprevention for colorectal neoplasia: experience from the large-scale NORCCAP screening trial

The objective of this study was to evaluate the potential beneficial effects of non-steroidal anti-inflammatory drugs (NSAIDs) and/or acetylsalicylic acid (ASA) and hormone replacement therapy (HRT) on colorectal neoplasia, and to compare their effects with those of lifestyle-related risk factors in 12 960 individuals who underwent flexible sigmoidoscopy screening examination. The association between these factors and colonic neoplasia was assessed by logistic regression analysis. NSAIDs and/or ASA intake were associated with decreased risk of distal low grade adenoma (DLGA) (adjusted odds ratio (OR) 0.80, P trend=0.02) in men. The duration of HRT was inversely related to the risk of DLGA (OR 0.89, P trend=0.08). Current smoking increased the risk of DLGA and distal advanced neoplasia (DAN) in both men (OR 2.50, P<0.01) and women (OR 2.30, P<0.01). There was a significant positive trend for increasing risk of DLGA (OR 1.16, P<0.01) and DAN (OR 1.20, P=0.02) with increasing use of alcohol among men, but not among women. Prescription of NSAIDs and/or ASA for chronic conditions may not be expected to have a substantial preventive effect on colorectal neoplasia in comparison with the adverse effect of smoking and alcohol. This may be explained by an increased risk of colorectal neoplasia for patients with conditions for which NSAIDs or ASA are being prescribed.

Cyclooxygenase-2 inhibition prevents colorectal cancer: from the bench to the bed side

Cancer is predicted to become the leading cause of death--surpassing heart disease--by the end of this decade. Colorectal cancer is a major health concern, with more than 1,000,000 new cases and 500,000 deaths expected worldwide per year. There is much evidence to suggest a link between the consumption of non-steroidal anti-inflammatory drugs (NSAIDs) and the prevention of colorectal cancer (CRC). The consumption of NSAIDs is not problem free, and the number of deaths due to NSAIDs equals the number of deaths from AIDS or leukemia. Therefore, although chemoprevention of CRC is possible, drugs that have more acceptable side effect profiles than the currently available NSAIDs are required. Since up to 50% of polyps and 85% of colonic tumors in humans overexpress cyclooxygenase (COX-2), COX-2 inhibitors are an ideal drug candidate for CRC prevention or treatment.

Effect of concomitant polyethylene glycol and celecoxib on colonic aberrant crypt foci and tumors in F344 rats

We investigated whether celecoxib augments the protective effect of polyethylene glycol (PEG) on colonic aberrant crypt foci (ACF) and tumor formation in F344 rats treated with azoxymethane (AOM). Three groups of rats received AOM: I (AOM alone), II (PEG), and III (PEG/celecoxib). PEG reduced the mean number of total ACF per colon from 190 to 141 (P < 0.05; 26% reduction) and > or = 4-crypt ACF from 95 to 58 (P < 0.01; 39%). Group III rats had a greater proportion of their ACF distally; whereas transverse colon ACF were reduced approximately 50%, distal ACF were reduced by only approximately 8% (P < 0.05). Of 13 large bowel tumors, 8 were in Group I, 4 in Group II, and 1 in Group III rats (P = 0.02). Thus in AOM-treated rats celecoxib appeared to enhance the PEG-induced reduction in colonic tumor formation, and in transverse but not distal or whole-colon ACF.

5-aminosalicylic acid is an attractive candidate agent for chemoprevention of colon cancer in patients with inflammatory bowel disease

Inflammatory bowel disease (IBD) is classically subdivided into ulcerative colitis (UC) and Crohn’s disease (CD). Patients with IBD have increased risk for colorectal cancer. Because the pathogenesis of colorectal carcinoma has not been entirely defined yet and there is no ideal treatment for colon cancer, cancer prevention has become increasingly important in patients with IBD. The two adopted methods to prevent the development of colon cancer in clinical practice include the prophylactic colectomy and colonoscopic surveillance. But patients and physicians seldom accept colectomy as a routine preventive method and most patients do not undergo appropriate colonoscopic surveillance. Chemoprevention refers to the use of natural or synthetic chemical agents to reverse, suppress, or to delay the process of carcinogenesis. Chemoprevention is a particularly useful method in the management of patients at high risk for the development of specific cancers based on inborn genetic susceptibility, the presence of cancer-associated disease, or other known risk factors. Prevention of colorectal cancer by administration of chemopreventive agents is one of the most promising options for IBD patients who are at increased risks of the disease. The chemopreventive efficacy of nonsteroidal anti-inflammatory drugs (NSAIDs) against intestinal tumors has been well established. But with reports that NSAIDs aggravated the symptoms of colitis, their sustained use for the purpose of cancer chemoprevention has been relatively contraindicated in IBD patients. Another hopeful candidate chemoprevention drug for IBD patients is 5-aminosalicylic acid (5-ASA), which is well tolerated by most patients and has limited systemic adverse effects, and no gastrointestinal toxicity. 5-ASA lacks the well-known side effects of long-term NSAIDs use. Retrospective correlative studies have suggested that the long-term use of 5-ASA in IBD patients may significantly reduce the risk of development of colorectal cancer. According to the literature, this agent might well satisfy clinical expectations with respect to a safe and effective chemopreventive agent.

Nitric-oxide-donating NSAIDs as agents for cancer prevention

Nitric-oxide-donating nonsteroidal anti-inflammatory drugs (NO-NSAIDs), which consist of an NSAID with an NO-donating moiety covalently attached to it, promise to contribute significantly towards the development of effective chemoprevention strategies against cancer. NO-NSAIDs inhibit the growth of cultured cancer cells 10-6000-fold more potently than their parent NSAIDs and prevent colon cancer in animal tumor models. Clinical data indicate that they are extremely safe. Mechanistically, NO-aspirin, the best-studied NO-NSAID, has pleiotropic effects on cell signaling (it inhibits Wnt signaling, induces nitric oxide synthase and NF-kappaB activation and induces cyclooxygenase-2 expression), and this mechanistic redundancy might be central to its mode of action against cancer. The apparent safety and superior efficacy of NO-NSAIDs makes them promising chemopreventive agents against cancer.

Ibuprofen Inhibits Survival of Bladder Cancer Cells by Induced Expression of the p75NTR Tumor Suppressor Protein

Nonsteroidal anti-inflammatory drugs (NSAIDs) are used to reduce inflammation and as analgesics by inhibition of cyclooxygenase-2. At higher concentrations, some NSAIDs inhibit proliferation and induce apoptosis of cancer cells. Although several molecular mechanisms have been postulated to explain the anticancer effects of NSAIDs, they do not involve merely the inhibition of cyclooxygenase-2, and a more proximate initiator molecule may be regulated by NSAIDs to inhibit growth. The p75 neurotrophin receptor (p75NTR) is a proximate cell membrane receptor glycoprotein that has been identified as a tumor and metastasis suppressor. We observed that NSAID treatment of cell lines from bladder and other organs induced expression of the p75NTR protein. Of the different types of NSAIDs examined, ibuprofen was more efficacious than aspirin and acetaminophen and comparable with (R)-flurbiprofen and indomethacin in induction of p75NTR protein expression. This rank order NSAID induction of the p75NTR protein correlated with the ability of these NSAIDs to reduce cancer cell survival. To examine a mechanistic relationship between ibuprofen induction of p75NTR protein and inhibition of survival, bladder cancer cells were transfected with ponasterone A-inducible vectors that expressed a death domain-deleted (DeltaDD) or intracellular domain-deleted (DeltaICD) p75NTR product that acts as a dominant negative antagonist of the intact p75NTR protein. Expression of DeltaDD and DeltaICD rescued cells from ibuprofen inhibition of growth. These observations suggest that p75NTR is an important upstream modulator of the anticancer effects of NSAIDs and that ibuprofen induction of the p75NTR protein establishes an alternate mechanism by which ibuprofen may exert an anticancer effect.

The relationship between cyclooxygenase-2 expression and characteristics of malignant transformation in human colorectal adenomas

BACKGROUND AND AIMS

Cyclooxygenase 2 (COX-2) is a target of aspirin and other non-steroidal anti-inflammatory drugs and is implicated in the pathogenesis of colorectal cancer. The objective of this study was to evaluate the extent of COX-2 in pre-malignant colorectal polyps and to assess the relationship between COX-2 and the level of dysplasia in these lesions.

METHODS

Whole polypectomy specimens were retrieved from 123 patients by endoscopic or surgical resection. Following formalin fixation and paraffin embedding, the polyps were evaluated histologically for size, type and grade of dysplasia. The extent of COX-2 expression was measured by the avidin-biotin immunohistochemical technique using a monoclonal COX-2 antibody. The extent of COX-2 expression was graded according to percentage epithelial COX-2 expression.

RESULTS

The polyps were of the following histological types: 10 hyperplastic, 35 tubular adenomas, 61 tubulovillous adenomas and 17 villous adenomas. Twenty showed mild dysplasia, 65 moderate dysplasia, and 28 focal or severe dysplasia (including eight with focal invasion). The average polyp size was 1.7 cm. Nine hyperplastic polyps were COX-2-negative and one was COX-2-positive. COX-2 expression was more extensive in larger polyps and in polyps with a higher villous component. There was a significant increase in the extent of COX-2 protein with increasing severity of dysplasia. Within a polyp, there was a focal corresponding increase in COX-2 expression within epithelium showing a higher grade of dysplasia.

CONCLUSIONS

COX-2 expression is related directly to colorectal adenomatous polyp size, type and grade of dysplasia. This suggests that the role of COX-2 in colorectal cancer may be at an early stage in the adenoma-to-carcinoma sequence and supports the suggestion that inhibition of COX-2 may be useful chemoprevention for this disease.

Polymorphisms in PTGS1 (=COX-1) and Risk of Colorectal Polyps

Two isoforms of prostaglandin H synthase (PTGS = COX) are key enzymes in prostaglandin synthesis and primary targets for aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs). Use of aspirin or other NSAIDs is associated with a lower risk and reduced recurrence of colorectal adenomas, established precursors of adenocarcinoma. This study investigated risk of colorectal adenomatous and hyperplastic polyps associated with several polymorphisms in the coding region of PTGS1. Within the Minnesota polyp case-control study, patients with colorectal adenomatous (n = 521) or hyperplastic (n = 194) polyps and n = 621 polyp-free controls were genotyped for four PTGS1 polymorphisms (R8W, L15-L16del, P17L, L237M); these had been predicted to affect protein function based on sequence-homology software. Age- and sex-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) were computed. Whereas there was no appreciable difference in adenoma or hyperplastic polyp risk associated with R8W, P17L, and L237M, an increased risk was observed for individuals heterozygous for the L15-L16del polymorphism (OR = 3.6, 95% CI 1.2–11.2). The variant L15-L16del allele appeared to be associated with a stronger increase in adenoma risk among nonusers of aspirin/other NSAIDs. The reduced risk observed with aspirin/other NSAID use was limited to those wild type for P17L [PP users: OR = 0.6 (0.5–0.8) versus PP nonusers: 1.0 (referent) (P interaction = 0.03)]. To our knowledge, this study represents the first investigation of polymorphisms in PTGS1 and risk of colorectal polyps. The L15-L16del variant allele may result in an increased risk of colorectal adenomas, whereas P17L may be relevant to the pharmacogenetics of aspirin. These preliminary findings require confirmation in larger studies of colorectal neoplasia.

Colon cancer: prevalence, screening, gene expression and mutation, and risk factors and assessment

Colon cancer detection at an early stage and identifying susceptible individuals can result in reduced mortality from this prevalent cancer. Genetic events leading to the development of this cancer involve a multistage progression of adenoma polyps to invasive metastatic carcinomas. Currently, there is no satisfactory screening method that is highly specific, sensitive, or reliable. Dietary patterns associated with the greatest increase in colon cancer risk are the ones that typify a diet rich in fat and calories, and low in vegetable, fruits, and fibers. Genetic susceptibility to environmental carcinogenesis must be factored into the risk assessment for this cancer. Many genes have been shown to be associated with increased expression and mutations in colorectal cancer patients. These genes have been reviewed; it is hoped that by carefully selecting a number of them, a molecular approach that is suitable for arriving at a tumorigenic expression index is developed, which will reliably detect this cancer at an early stage (i.e., before it metastasizes), especially in exfoliated samples (e.g., stool and blood), so that appropriate intervention strategies can be implemented. Illustrated herein is the utility of employing real-time reverse transcriptase polymerase chain reaction (RT-PCR) to quantitatively measure gene expression, and develop an index that is specific for this cancer, which if perfected may result in a reliable and sensitive screening technique for colorectal cancer detection.

Daily soluble aspirin and prevention of colorectal adenoma recurrence: one-year results of the APACC trial

BACKGROUND & AIMS

Epidemiologic and experimental studies have suggested that aspirin intake reduces the risk for colorectal carcinogenesis. However, the available data are not sufficient to serve as the basis for firm recommendations.

METHODS

We randomly assigned 272 patients with a history of colorectal adenomas (at least one more than 5 mm in diameter, or more than 3) to daily lysine acetylsalicylate (160 or 300 mg/day) or placebo for 4 years. The primary end points were adenoma recurrence after 1 and 4 years. These results are those of the year 1 colonoscopy.

RESULTS

Among the 238 patients who completed the year 1 colonoscopy, at least one adenoma was observed in 38 patients of the 126 (30%) in the aspirin group and in 46 of the 112 (41%) in the placebo group; relative risk was 0.73 (95% confidence interval [CI]: 0.52-1.04; P = 0.08). At least one adenoma of more than 5 mm diameter was observed in 13 patients (10%) in the aspirin group and 26 (23%) in the placebo group (P = 0.01). The corresponding numbers for adenomas more than 10 mm in diameter were one (1%) and 7 (6%) (P = 0.05). Stepwise regression showed that independent factors associated with lower adenoma recurrence are aspirin treatment (adenoma >5 mm, P = 0.01), absence of personal history of adenoma before the entry colonoscopy (P = 0.01), and initial adenomatous polyp burden less than 10 mm (P = 0.001).

CONCLUSIONS

Daily soluble aspirin is associated with a reduction in the risk for recurrent adenomas found at colonoscopy 1 year after starting treatment.

Risk of cancer in a large cohort of nonaspirin NSAID users: a population-based study

There is increasing evidence of an inverse association between use of nonsteroidal anti-inflammatory drugs (NSAIDs) and risk of colorectal cancer. However, data regarding other cancer sites are limited. Using data from the population-based North Jutland Prescription Database and the Danish Cancer Registry, we compared cancer incidence among 172 057 individuals prescribed nonaspirin NSAIDs with expected incidence (based on county-specific cancer rates) during a 9-year study period. A total of 6081 incident cancer cases were diagnosed among NSAID users vs 5722 expected (standardised incidence ratio (SIR) 1.1, 95% confidence interval (CI)1.0-1.1). The SIRs for colon and rectal cancer among persons who obtained 10 or more prescriptions were 0.7 (95% CI 0.6-0.9) and 0.6 (95% CI 0.4-0.9), respectively. Similarly, reduced risk estimates were found for stomach (SIR 0.7, 95% CI 0.4-1.1) and ovarian cancer (SIR 0.7, 95% CI 0.4-1.0). Standardised incidence ratios for other cancers among those with 10 or more prescriptions tended to be close to 1.0, except for lung, kidney, and prostate cancers with SIRs of 1.3 (95% CI 1.1-1.6), 1.4 (95% CI 0.9-2.1), and 1.6 (95% CI 1.3-2.0), respectively. We found protective associations of NSAIDs against colon, rectal, stomach, and ovarian cancer. Reasons for the increased risk for some cancer sites are not clear.

A randomized trial of aspirin to prevent colorectal adenomas in patients with previous colorectal cancer

BACKGROUND

Experimental studies in animals and observational studies in humans suggest that regular aspirin use may decrease the risk of colorectal adenomas, the precursors to most colorectal cancers.

METHODS

We conducted a randomized, double-blind trial to determine the effect of aspirin on the incidence of colorectal adenomas. We randomly assigned 635 patients with previous colorectal cancer to receive either 325 mg of aspirin per day or placebo. We determined the proportion of patients with adenomas, the number of recurrent adenomas, and the time to the development of adenoma between randomization and subsequent colonoscopic examinations. Relative risks were adjusted for age, sex, cancer stage, the number of colonoscopic examinations, and the time to a first colonoscopy. The study was terminated early by an independent data and safety monitoring board when statistically significant results were reported during a planned interim analysis.

RESULTS

A total of 517 randomized patients had at least one colonoscopic examination a median of 12.8 months after randomization. One or more adenomas were found in 17 percent of patients in the aspirin group and 27 percent of patients in the placebo group (P=0.004). The mean (+/-SD) number of adenomas was lower in the aspirin group than the placebo group (0.30+/-0.87 vs. 0.49+/-0.99, P=0.003 by the Wilcoxon test). The adjusted relative risk of any recurrent adenoma in the aspirin group, as compared with the placebo group, was 0.65 (95 percent confidence interval, 0.46 to 0.91). The time to the detection of a first adenoma was longer in the aspirin group than in the placebo group (hazard ratio for the detection of a new polyp, 0.64; 95 percent confidence interval, 0.43 to 0.94; P=0.022).

CONCLUSIONS

Daily use of aspirin is associated with a significant reduction in the incidence of colorectal adenomas in patients with previous colorectal cancer.

Family history of colon cancer: what does it mean and how is it useful?

BACKGROUND

Family history of colon cancer can be deconstructed into causal and noncausal explanations, which include genetic factors, environmental factors, gene-environment interactions, misclassification, and differences in screening.

METHODS

We investigated some of these causal and noncausal explanations by using data from a case-control study of colon cancer conducted among African Americans and whites in North Carolina. We examined the relationship between family history and polymorphisms in four genes (N-acetyltransferase 1 and 2 [NAT1, NAT2], methylenetetrahydrofolate reductase, and peroxisome proliferator-activated receptor gamma [PPARG]), environmental risk factors, the joint distributions of these genes and environmental risk factors, and the prevalence of colon cancer screening.

RESULTS

Participants with one or more first-degree relatives with colon cancer showed a slightly higher prevalence of at-risk genotypes for each locus, but results were statistically significant only for NAT2. Participants with a family history showed a higher prevalence of at-risk combinations of genotypes and environmental risk factors (NAT2 and well-done red meat consumption; PPARG and nonsteroidal anti-inflammatory medication use). The sensitivity and predictive value of family history for identifying persons with at-risk genotypes or environmental risk factors was low. History of cancer screening was similar in those with and without a family history.

CONCLUSIONS

Our results suggest that family history of colon cancer may represent aggregation of some genetic polymorphisms and environmental risk factors. Although it is premature to use family history as a screening tool when testing for genetic polymorphisms, further research is needed to identify additional genes and environmental factors that may be associated with family history.

Update on the cost-effectiveness of screening for colorectal neoplasia

Colorectal cancer is an ideal target for population screening because it is a prevalent disease with an identifiable precursor lesion that, when treated, favorably alters the natural history of the disease. Several strategies for screening have illustrated efficacy, including fecal occult blood testing, sigmoidoscopy and colonoscopy. Cost-effectiveness analyses have been performed to determine whether the resources required to implement screening are justified by potential gains. The U.S. Preventive Services Task Force recently commissioned a study on the cost-effectiveness of colorectal cancer screening, which revealed that screening was cost-effective compared to no screening. However, it could not be confirmed which strategy would save the most life-years, nor which was most cost-effective. Since publication of this review, several additional cost-effectiveness analyses have been performed. These studies confirm that screening average risk patients at age 50 by a variety of available strategies is likely to be reasonable by current standards for resource utilization, and that either colonoscopy every 10 years (or once at age 65) or the combination of annual fecal occult blood testing with sigmoidoscopy every 5 years are viable alternatives. Additional economic analyses have examined the use of aspirin chemoprophylaxis to prevent colorectal cancer either alone or as an adjunct to screening strategies. These studies reaffirm the cost-effectiveness of colorectal cancer screening, but illustrate that aspirin chemoprophylaxis is unlikely to be associated with gains for which society would be willing to pay. At present, the decision to choose one colorectal screening strategy over another is based on availability of screening modalities, patient and provider preferences, and associated adherence to screening recommendations. Assessment of preference and development of interventions to increase adherence to screening should be a focus of research in the future.