Relationship between APC genotype, polyp distribution, and oral sulindac treatment in the colon and rectum of patients with familial adenomatous polyposis

Nonsteroidal Anti-inflammatory Drugs for Chemoprevention in Patients With Familial Adenomatous Polyposis: A Systematic Review and Meta-Analysis

Background and Aims

Published literature shows mixed reports of the benefits of nonsteroidal anti-inflammatory drugs (NSAIDs) on reducing colorectal polyps in patients with familial adenomatous polyposis (FAP). We conducted a systematic review and performed a meta-analysis to assess the impact of NSAIDs on colorectal polyp burden in patients with FAP.

Methods

We searched PubMed, EMBASE, and Cochrane for randomized controlled trials (RCTs) comparing the effect of NSAIDs vs placebo on the percent change in polyp number and polyp size in patients with FAP. Mean differences between the 2 study arms were pooled using RevMan. The risk of bias (RoB) was assessed using the Cochrane Risk of Bias tool for RCTs, and certainty in the evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation methodology.

Results

The search strategy identified 1021 studies, out of which we included 8 RCTs with a total of 279 patients. Treatment for 6.4 ± 2.2 months with NSAIDs reduced polyp numbers by -17.4% (95% confidence interval -26.41%, -8.29%) (low certainty [I2 89%] due to imprecision and issues with RoB) and polyp size by -15.9% (95% confidence interval -24.98%, -6.73%) (very low certainty (I2 84%) due to imprecision, inconsistency, and issues with RoB). The most common gastrointestinal adverse events reported were stomatitis, diarrhea, and abdominal pain. Side effects leading to drug discontinuation were gastroenteritis and drug allergy.

Conclusion

Short-term use of NSAIDs reduced polyp number and polyp size but with low to very low certainty of evidence. Further large multicenter studies are needed to further explore NSAIDs as a chemopreventive measure in patients with FAP.

Long-term chemoprevention in patients with adenomatous polyposis coli: an observational study

Prospective short-term studies on effectiveness of non-steroidal anti-inflammatory drugs (NSAIDs) point towards a decrease in the number and size of polyps. Effectiveness and safety in the prevention of progression in familial polyposis with NSAIDs in long-term use, which is the prerequisite for therapeutic evaluation in prospective studies, is unknown. The total absolute observation period of 54 patients under sulindac was 399 patient years with a mean of 7.4 (2-19) years per patient. 36 patients (66.7%) showed a fast decrease of polyp burden, 8 (14.8%) were slow responders, and 9 (16.7%) had stable disease; one patient had a slow progression. Upper gastrointestinal (GI) polyp burden remained stable in 47% patients, increased in 31%, and improved in 22%. Advanced adenomas were found in 8 patients only within the first 5 years of chemoprevention, no patient developed desmoid disease, anamnestically evaluated on every follow-up. There were no life-threatening side-effects. Dosage and delivery pattern were essential for effectiveness. This study provides evidence that chemoprevention with sulindac is effective and safe and can, either alone or in combination with other drugs, become a long-term management option in cases of adenomatous polyposis. These results justify further long-term prospective chemoprevention studies to elaborate treatment protocols and guidelines.

Targeting of oncogenic signaling pathways by berberine for treatment of colorectal cancer

Studies indicate that inhibiting a single signaling pathway or one single product of a gene is insufficient for the prevention and treatment of cancer. This is due to the fact that dysregulation must occur in more than 500 genes in order to produce a cancerous phenotype. Despite this evidence, available drugs used for cancer treatment focus on a single target. Meanwhile, berberine as a nutraceutical is capable of targeting various processes involved in tumor development including proliferation, invasion, angiogenesis, and metastasis. In comparison with synthetic agents, berberine is cheaper, safer, and more available. Berberine has shown anti-inflammatory properties which make it an ideal option in order to prevent inflammation-associated cancers. Colorectal cancer is one of the most common cancers all over the world and its incidence is increasing each day. Therefore, further investigations about berberine could be helpful in the discovery of novel agents for preventing and/or treating colorectal cancer. This review emphasizes the studies investigating the roles of berberine in colorectal cancer such as controlling cell signaling pathways, inducing apoptosis, regulating microRNAs, attenuating oxidative stress, and affecting inflammation.

Berberine binds RXRα to suppress β-catenin signaling in colon cancer cells

Berberine, an isoquinoline alkaloid, is a traditional oriental medicine used to treat diarrhea and gastroenteritis. Recently, we reported that it could inhibit the growth of intestinal polyp in animals and in patients with the familial adenomatous polyposis by downregulating β-catenin signaling. However, the intracellular target mediating the effects of berberine remains elusive. Here, we provide evidence that berberine inhibits β-catenin function via directly binding to a unique region comprising residues Gln275, Arg316 and Arg371 in nuclear receptor retinoid X receptor alpha (RXRα), where berberine concomitantly binding to and synergistically activating RXRα with 9-cis-retinoic acid (9-cis-RA), a natural ligand binding to the classical ligand-binding pocket of RXRα. Berberine binding promotes RXRα interaction with nuclear β-catenin, leading to c-Cbl mediated degradation of β-catenin, and consequently inhibits the proliferation of colon cancer cells. Furthermore, berberine suppresses the growth of human colon carcinoma xenograft in nude mice in an RXRα-dependent manner. Together, our study not only identifies RXRα as a direct protein target for berberine but also dissects their binding mode and validates that berberine indeed suppresses β-catenin signaling and cell growth in colon cancer via binding RXRα, which provide new strategies for the design of new RXRα-based antitumor agents and drug combinations.

Chemoprevention of colorectal cancer

Colorectal cancer has become one of the most prevalent malignant diseases for both men and women. Patients with inflammatory bowel diseases or certain inherited cancer syndromes are at high risk of developing colorectal cancer and have naturally the highest need for cancer prevention. In familial adenomatous polyposis (FAP) and Lynch syndrome, most of the underlying germline mutations can be detected by DNA sequencing, and medical counselling of affected individuals involves both surveillance tests and chemopreventive measures. However, as the mechanisms leading to colorectal cancer differ in these high-risk groups, the molecular action of chemopreventive drugs needs to be adjusted to the certain pathway of carcinogenesis. In the last decades, a number of drugs have been tested, including sulindac, aspirin, celecoxib, and mesalazine, but some of them are still controversially discussed. This review summarizes the advances and current standards of colorectal cancer prevention in patients with inflammatory bowel disease, FAP and Lynch syndrome.

A phase Ib study of the effects of black raspberries on rectal polyps in patients with familial adenomatous polyposis

Familial adenomatous polyposis (FAP) is characterized by the early onset of colonic polyposis and a high risk for colorectal cancer. FAP is treated by colectomy followed by lifelong removal of rectal polyps. This study determined whether black raspberries (BRBs) might regress rectal polyps in patients with FAP. Fourteen patients with FAP were treated with BRBs daily for 9 months. Seven patients received BRB powder orally plus two BRB suppositories inserted into the rectum at bedtime. The other 7 received an oral placebo plus the suppositories. Rectal polyp counts and polyp sizes were obtained at time zero and after 9 months of BRB treatment. Polyps and adjacent normal tissue were collected at both time points. The burden (P = 0.036) but not number (P = 0.069) of rectal polyps was significantly decreased. No benefit was noted with the addition of oral BRBs. Three patients were nonresponders. BRBs significantly decreased cellular proliferation, DNA methylation methyl transferase 1 protein expression, and p16 promoter methylation, but not promoter methylation of the Wnt pathway antagonists, SFRP2 and WIF1, in rectal polyps (adenomas) from responders but not from nonresponders. The MBD-seq assay revealed more demethylated transcription start sites (TSS), including those for miRNAs, in BRB-treated adenomas from the responders. In conclusion, BRB suppositories seem sufficient for regressing rectal polyps in patients with FAP.

Nonsteroidal anti-inflammatory drug-induced hepatoxicity

Nonsteroidal anti-inflammatory drugs are among the most prescribed medications worldwide. After antibiotics and anticonvulsants they are considered the most common medications associated with drug-induced liver injury mainly through an idiosyncratic form of hepatotoxicity. In rare cases severe hepatotoxicity has been described with significant morbidity and mortality. Genetic risk factors have been reported with diclofenac and lumiracoxib. Postmarketing surveillance and monitoring is crucial to identify severe cases of hepatotoxicity.

Utilizing endoscopic technology to reveal real-time proteomic alterations in response to chemoprevention

Cancer chemoprevention approaches use either pharmacological or dietary agents to impede, arrest or reverse the carcinogenic process. Although several agents have shown effectiveness against colon cancer, present intervention strategies provide only partial reduction. In this study, we utilized high-resolution endoscopy to obtain colon tumor biopsy specimens from Apc mutant mice before and after 2-wk sulindac intervention. To acquire information beyond genomics, proteome analysis using the ProteomeLab PF2D platform was implemented to generate 2-D protein expression maps from biopsies. Chromatograms produced common signature profiles between sulindac and nonsulindac treated samples, and contrasting profiles termed "fingerprints". We selected a double peak that appeared in tumor biopsies from sulindac-treated mice. Further analyses using MS sequencing identified this protein as histone H2B. The location of H2B in the 1(st) dimension strongly suggested PTM, consistent with identification of two oxidized methionines. While further studies on sulindac proteomic fingerprints are underway, this study demonstrates the feasibility and advantages of "real-time" proteomic analysis for obtaining information on biomarker discovery and drug activity that would not be revealed by a genetic assay. This approach should be broadly applicable for assessing lesion responsiveness in a wide range of translational and human clinical studies.

Chemoprevention in familial adenomatous polyposis

Familial adenomatous polyposis (FAP) predictably leads to adenomas and eventual adenocarcinomas in the lower gastrointestinal tract and less frequently, the upper gastrointestinal tract. Chemopreventive strategies have been studied in FAP patients to delay the development of adenomas in the upper and lower gastrointestinal tract, as well as to prevent recurrence of adenomas in the retained rectum of patients after prophylactic surgery with colectomy and ileorectal anastamosis (IRA). The nonsteroidal anti-inflammatory drug (NSAID) sulindac and selective cyclooxygenase-2 (COX-2) inhibitor celecoxib reduce polyposis of the retained rectum after colectomy with IRA. Reports of cardiovascular risks of some NSAIDs and selective COX-2 inhibitors have led to promising studies of lower doses in combination with ursodeoxycholic acid, statin, and difluoromethylornithine. Curcumin and eicosapentaenoic acid show efficacy in small clinical trials of FAP chemoprevention. This article will review the concept of chemoprevention and the current clinical literature in FAP chemoprevention.

Non-steroidal anti-inflammatory drugs: What is the actual risk of liver damage?

Non-steroidal anti-inflammatory drugs (NSAIDs) constitute a family of drugs, which taken as a group, represents one of the most frequently prescribed around the world. Thus, not surprisingly NSAIDs, along with anti-infectious agents, list on the top for causes of Drug-Induced Liver Injury (DILI). The incidence of liver disease induced by NSAIDs reported in clinical studies is fairly uniform ranging from 0.29/100 000 [95% confidence interval (CI): 0.17-051] to 9/100 000 (95% CI: 6-15). However, compared with these results, a higher risk of liver-related hospitalizations was reported (3-23 per 100 000 patients). NSAIDs exhibit a broad spectrum of liver damage ranging from asymptomatic, transient, hyper-transaminasemia to fulminant hepatic failure. However, under-reporting of asymptomatic, mild cases, as well as of those with transient liver-tests alteration, in conjunction with reports non-compliant with pharmacovigilance criteria to ascertain DILI and flawed epidemiological studies, jeopardize the chance to ascertain the actual risk of NSAIDs hepatotoxicity. Several NSAIDs, namely bromfenac, ibufenac and benoxaprofen, have been withdrawn from the market due to hepatotoxicity; others like nimesulide were never marketed in some countries and withdrawn in others. Indeed, the controversy concerning the actual risk of severe liver disease persists within NSAIDs research. The present work intends (1) to provide a critical analysis of the dissimilar results currently available in the literature concerning the epidemiology of NSAIDS hepatotoxicity; and (2) to review the risk of hepatotoxicity for each one of the most commonly employed compounds of the NSAIDs family, based on past and recently published data.

Mechanisms of intestinal inflammation and development of associated cancers: lessons learned from mouse models

Chronic inflammation is strongly associated with approximately 1/5th of all human cancers. Arising from combinations of factors such as environmental exposures, diet, inherited gene polymorphisms, infections, or from dysfunctions of the immune response, chronic inflammation begins as an attempt of the body to remove injurious stimuli; however, over time, this results in continuous tissue destruction and promotion and maintenance of carcinogenesis. Here we focus on intestinal inflammation and its associated cancers, a group of diseases on the rise and affecting millions of people worldwide. Intestinal inflammation can be widely grouped into inflammatory bowel diseases (ulcerative colitis and Crohn's disease) and celiac disease. Long-standing intestinal inflammation is associated with colorectal cancer and small-bowel adenocarcinoma, as well as extraintestinal manifestations, including lymphomas and autoimmune diseases. This article highlights potential mechanisms of pathogenesis in inflammatory bowel diseases and celiac disease, as well as those involved in the progression to associated cancers, most of which have been identified from studies utilizing mouse models of intestinal inflammation. Mouse models of intestinal inflammation can be widely grouped into chemically induced models; genetic models, which make up the bulk of the studied models; adoptive transfer models; and spontaneous models. Studies in these models have lead to the understanding that persistent antigen exposure in the intestinal lumen, in combination with loss of epithelial barrier function, and dysfunction and dysregulation of the innate and adaptive immune responses lead to chronic intestinal inflammation. Transcriptional changes in this environment leading to cell survival, hyperplasia, promotion of angiogenesis, persistent DNA damage, or insufficient repair of DNA damage due to an excess of proinflammatory mediators are then thought to lead to sustained malignant transformation. With regards to extraintestinal manifestations such as lymphoma, however, more suitable models are required to further investigate the complex and heterogeneous mechanisms that may be at play.

Sulindac confers high level ischemic protection to the heart through late preconditioning mechanisms

We have recently shown that sulindac, an anti-inflammatory drug, enhances the killing of cancer cells, but not normal cells, under conditions of oxidative stress, by mechanisms unrelated to its cyclooxygenase (COX) inhibition. To further study the protective effect of sulindac on cells exposed to oxidative stress, we have investigated the effect of sulindac on rat cardiac myocytes subjected to hypoxia/reoxygenation, as well as in a Langendorff model of myocardial ischemia. Low levels of sulindac could protect cardiac myocytes against cell death due to hypoxia/reoxygenation. In the Langendorff model sulindac provided significant protection against cell death, when the drug was fed to the animals before the removal of the heart for the Langendorff procedure. The results indicate that the primary protective effect of sulindac in these experiments does not involve its role as a COX inhibitor. Numerous signaling pathways have been implicated in myocardial protective mechanisms, many of which involve fluctuations in reactive oxygen species (ROS) levels. The results suggest that low levels of sulindac can induce a preconditioning response, triggered by ROS, to protect cardiac tissues against oxidative damage. Blocking of preconditioning pathways by administration of the PKC blocker chelerythrine abrogated the ischemic protection afforded by sulindac. Secondly, after feeding of sulindac, two end-effectors of preconditioning, inducible nitric oxide synthase and heat shock protein 27, were found to be markedly induced in the heart, dependent on PKC. These results suggest that sulindac may have therapeutic potential as a preconditioning agent.

Sulindac enhances the killing of cancer cells exposed to oxidative stress

Background

Sulindac is an FDA-approved non-steroidal anti-inflammatory drug (NSAID) that affects prostaglandin production by inhibiting cyclooxygenases (COX) 1 and 2. Sulindac has also been of interest for more than decade as a chemopreventive for adenomatous colorectal polyps and colon cancer.

Principal Findings

Pretreatment of human colon and lung cancer cells with sulindac enhances killing by an oxidizing agent such as tert-butyl hydroperoxide (TBHP) or hydrogen peroxide. This effect does not involve cyclooxygenase (COX) inhibition. However, under the conditions used, there is a significant increase in reactive oxygen species (ROS) within the cancer cells and a loss of mitochondrial membrane potential, suggesting that cell death is due to apoptosis, which was confirmed by Tunel assay. In contrast, this enhanced killing was not observed with normal lung or colon cells.

Significance

These results indicate that normal and cancer cells handle oxidative stress in different ways and sulindac can enhance this difference. The combination of sulindac and an oxidizing agent could have therapeutic value.

Chemoprevention with special reference to inherited colorectal cancer

Familial Adenomatous Polyposis (FAP) is a model for the adenoma-carcinoma sequence in several respects. One important area in which FAP serves as a model is chemoprevention. Early prevention trials mainly utilized micronutrients and were largely unsuccessful in preventing or causing regression of adenomas. A new era was ushered in by the recognition that antiarthritic doses of a nonsteroidal anti-inflammatory agent (NSAID), sulindac, could actually induce regression of colorectal adenomas in patients with FAP. Follow-up studies showed positive but variable long-term efficacy for colorectal adenomas, but sulindac appears to lack significant benefit in regressing duodenal adenomas or preventing initial occurrence of adenomas in APC mutation carriers. Due to the well-known side effects of traditional NSAIDs, selective COX-2 inhibitors have been studied rather extensively. Celecoxib has shown benefit in regressing colorectal adenomas and appears to have some duodenal activity as well. Rofecoxib, in smaller trials, showed efficacy as well. However, the entire field of NSAID research in chemoprevention is undergoing reexamination in light of recent demonstration of cardiovascular toxicity in nonfamilial or sporadic adenoma prevention trials. Whether NSAIDs will have a significant future in FAP chemoprevention will depend on a sober assessment of risks and benefits. These same issues will likely foster a more intensive search for new agents. FAP will undoubtedly continue to have a lead role in the testing of new agents, both in the interest of FAP management as such, and in anticipation of trials in nonfamilial adenomas, a problem with even greater societal impact. The historical development of chemoprevention in FAP will be presented, with an emphasis on issues of trial design.

Effect of the non-steroidal anti-inflammatory drug sulindac on colorectal adenomas of uncolectomized familial adenomatous polyposis

BACKGROUND

The aim of the present study was to elucidate the effect of sulindac on uncolectomized familial adenomatous polyposis (FAP).

METHODS

Seven FAP patients (SU group) without proctocolectomy were given sulindac 300 mg/day orally for 12 months. Six FAP patients without sulindac (non-SU group) served as controls. Colorectal lesions were assessed by protrusion index (no. radiolucent areas/cm(2); PI) under barium enema examination and non-polypoid lesion were assessed under chromoscopy prior to and at the end of the observation period. In the SU group, germline adenomatous polyposis coli (APC) mutation was determined by protein truncation test.

RESULTS

In the SU group, PI decreased significantly in the distal colon (from 3.0 +/- 1.1 to 1.1 +/- 0.8/cm(2), P < 0.02) and in the proximal colon (from 3.4 +/- 2.4 to 0.9 +/- 1.3/cm(2), P < 0.02). The PI in the non-SU group slightly but significantly increased in the distal colon (from 1.0 +/- 0.8 to 1.2 +/- 0.9/cm(2); P < 0.05) and it remained unchanged in the proximal colon (from 0.6 +/- 0.3 to 0.7 +/- 0.3/cm(2); P > 0.05). Chromoscopy at the end of observation identified non-polypoid lesions in five patients in the SU group, whereas such lesions were not found in the non-SU group (71% vs 0%, P = 0.016). Decrease in PI was not different among distal APC mutation (exons 1-9), proximal APC mutation (exons 10-15) and negative mutation.

CONCLUSION

Sulindac reduces colorectal adenomas of protruding type in uncolectomized FAP. The effect of sulindac may be unrelated to genotype of FAP.

Colonic surgery in patients with juvenile polyposis syndrome: a case series

PURPOSE

Juvenile polyposis syndrome is characterized by multiple hamartomatous polyps in the large intestine. When indicated, the surgical choices in symptomatic juvenile polyposis syndrome patients are colectomy with ileorectal anastomosis or proctocolectomy with pouch. The aim of this study was to evaluate the long-term outcomes of the surgical options in juvenile polyposis syndrome patients who present with symptomatic colonic polyps.

METHODS

The charts of all juvenile polyposis syndrome patients who had had at least one colonic operation since 1953 in our institution were reviewed. The following data were abstracted: demographics, the number and site of the polyps, symptoms, the intervals and types of the colonic operation, follow-up, and the patients' current status.

RESULTS

There were 13 patients (6 males) with a median age of 10 years (range, 1-50 years) at the time of diagnosis. Patients had colonic (n = 13), rectal (n = 12), and gastric (n = 6) polyps. Rectal bleeding (n = 11) was the most common presenting symptom. Three patients underwent proctectomy as the initial operation. Although a rectum-preserving operation was initially performed in ten patients, a subsequent proctectomy was required in five of them within a median of 9 years (range, 6-34 years). Therefore, eight patients had their rectum removed during the study period; five had an ileal pouch-anal anastomosis, one had a Koch pouch as a restorative surgery, and two had an end ileostomy. No relation was observed between the number of colonic and rectal polyps and the type of surgery or the need for proctectomy. Patients were followed up a median of 3 years (range, 2-24 years) after their ultimate operations. During this period, one patient (20 percent) who underwent restorative proctectomy and 4 patients (80 percent) whose rectums were preserved required multiple endoscopic polypectomies for recurrent polyps in the pouch (first patient) or their rectums (the other four patients). The patient who underwent the Koch procedure required surgery for recurrent polyps in her pouch.

CONCLUSIONS

One-half of the patients who initially underwent rectal preservation required subsequent proctectomy. The number of colonic or rectal polyps does not influence the choice of the surgical procedure. Both restorative proctocolectomy and subtotal colectomy with ileorectal anastomosis need endoscopic follow-up because of the high recurrence rates of juvenile polyps in the remnant rectum or pouch.

[Extracolonic manifestations of familial adenomatous polyposis: incidence and impact on the disease outcome]

BACKGROUND

Familial adenomatous polyposis is a hereditary disease with autossomic and dominant features, frequently associated to many extracolonic manifestations.

AIM

To report extracolonic manifestations incidence and to analyze its impact on the disease's outcome.

PATIENTS AND METHODS

Revision of patient charts treated from 1977 to 2001, relating associated extracolonic manifestations and its complications.

RESULTS

Among 59 familial adenomatous polyposis patients, 23 (38,9%) presented some extracolonic manifestations at diagnosis or during follow-up. There were registered 37 different extracolonic manifestations (1.6 per patient). The most common manifestations were osteomas and congenital hypertrophy of the retinal pigment epithelium, diagnosed in 25% and 20% of the investigated patients, respectively. Other extracolonic manifestations were represented by upper digestive adenomas, epidermoid cysts, desmoid tumor (seven each), gastric cancer (three) and tireoid cancer (two). Desmoid-associated complications were reported in six patients, being intestinal obstruction in four and hidronephrosis in two; two deaths (28,5%) were registered.

CONCLUSIONS

Extracolonic manifestations incidence is high (40%) and may affect disease's outcome and patient's quality of life. For these reasons, the research, prevention and adequate treatment of extracolonic manifestations turn into vital importance in familial adenomatous polyposis patients.

Hepatotoxicity associated with non-steroidal anti-inflammatory drugs

NSAIDs are one of most frequently prescribed agents in clinical practice. Whereas hepatotoxicity is a rare complication of most NSAIDs (typically 1 to 10 per 100,000 persons exposed), the high level of usage means that these drugs cause liver disease. Because of their divergent chemical structures, the mechanisms and clinicopathological manifestations of hepatotoxicity vary widely. The reactive metabolite syndrome, in which serious rash, eosinophilia, and other forms of tissue injury are common, may be incited by several NSAIDs, including newer agents. Women, people aged more than 50 years, and for some drugs, the type of arthritis, may be risk factors for drug-induced liver injury. The spectrum of NSAID-drug related hepatotoxicity continues to expand, with reports of interactive toxicity in adults with hepatitis C and recognition of rare cases of liver disease associated with non-selective, selective, and preferential COX-2 inhibitors. Better outcomes require people taking NSAIDs to be aware of possible drug reactions involving the liver, and prescribers should be vigilant for early symptoms of hepatotoxicity so that incriminated agents are discontinued promptly.

Are there two sides to colorectal cancer?

Colorectal carcinomas (CRC) that arise proximal (right) or distal (left) to the splenic flexure exhibit differences in incidence according to geographic region, age and gender. Together with observations that tumours in the hereditary cancer syndromes HNPCC and FAP occur predominantly in the right and left colon, respectively, the existence of 2 categories of CRC based on site of origin in the large bowel was proposed more than a decade ago. Differences between normal right and left colonic segments that could favour progression through different tumourigenic pathways are summarized in this review. Accumulating evidence suggests that the risk of CRC conferred by various environmental and genetic factors is different for proximal and distal tumours. Right- and left-sided tumours also exhibit different sensitivities to fluorouracil-based chemotherapy. Such differences are probably related to the molecular characteristics of the tumours, with the microsatellite instability and CpG island methylator phenotypes being associated with right-sided tumours and chromosomal instability with left-sided tumours. Future molecular-based classification systems for CRC that rely upon distinctive gene expression patterns may allow a clearer discrimination of subgroups than that provided by tumour site alone. Until then however, the existence of 2 broadly different groups of cancer defined by site of origin in the colon should be considered in the design of future epidemiologic studies as well as in the design of new clinical trials aimed at testing novel adjuvant therapies.

Therapeutic utility of aspirin in the ApcMin/+ murine model of colon carcinogenesis

BACKGROUND

In recent years it has become evident that nonsteroidal anti-inflammatory drugs, in particular aspirin represent a potential class of cancer chemotherapeutic agents. Despite the wealth of knowledge gained from epidemiological, clinical and animal studies, the effectiveness of aspirin to treat established gastrointestinal cancer has not been determined. The present study examines the ability of aspirin to treat established polyposis in Min/+ mice.

METHODS

Min/+ mice with established polyposis were treated orally once daily from 12-16 weeks of age with either drug vehicle or aspirin (25 mg/kg). Upon completion of treatment, the number, location and size of intestinal tumours was determined. Additional variables examined were the number of apoptotic cells within tumours and COX activity.

RESULTS

Administration of aspirin for 4 weeks to Min/+ mice produce no effect on tumour number compared to vehicle-treated Min/+ mice (65 +/- 8 vs. 63 +/- 9, respectively). In addition, aspirin had no effect on tumour size or location. However, aspirin treatment produced a greater than 2-fold (p<0.05) increase in the number of apoptotic positive cells within tumours and significantly decreased hepatic PGE2 content.

CONCLUSIONS

Aspirin was found to have no effect on tumour number and size when administered to Min/+ mice with established polyposis. The findings in the present study call in to question the utility of aspirin as a stand-alone treatment for established GI cancer. However, aspirin's ability to significantly promote apoptosis may render it suitable for use in combinatorial chemotherapy.

Hereditary colorectal cancer: keeping it in the family--the bowel cancer story

Up to 20% of colorectal cancers are thought to have a genetic component. Several familial syndromes are known to confer an increased risk for colorectal cancer. Advances in our understanding of these syndromes has improved the care delivered to, and the overall survival of, these patients. Genetic testing has great potential to further improve detection and direct subsequent preventative measures. The diagnosis, management and surveillance issues relating to some of the more commonly encountered syndromes - in particular Familial Adenomatous Polyposis and Hereditary Non-Polyposis Colorectal Cancer - are reviewed.