The protocol for a European double-blind trial of aspirin and resistant starch in familial adenomatous polyposis: the CAPP study. Concerted Action Polyposis Prevention

Dietary fibre for the prevention of recurrent colorectal adenomas and carcinomas

BACKGROUND

This is an update of the Cochrane review published in 2002.Colorectal cancer (CRC) is a major cause of morbidity and mortality in industrialised countries. Experimental evidence has supported the hypothesis that dietary fibre may protect against the development of CRC, although epidemiologic data have been inconclusive.

OBJECTIVES

To assess the effect of dietary fibre on the recurrence of colorectal adenomatous polyps in people with a known history of adenomatous polyps and on the incidence of CRC compared to placebo. Further, to identify the reported incidence of adverse effects, such as abdominal pain or diarrhoea, that resulted from the fibre intervention.

SEARCH METHODS

We identified randomised controlled trials (RCTs) from Cochrane Colorectal Cancer's Specialised Register, CENTRAL, MEDLINE and Embase (search date, 4 April 2016). We also searched ClinicalTrials.gov and WHO International Trials Registry Platform on October 2016.

SELECTION CRITERIA

We included RCTs or quasi-RCTs. The population were those having a history of adenomatous polyps, but no previous history of CRC, and repeated visualisation of the colon/rectum after at least two-years' follow-up. Dietary fibre was the intervention. The primary outcomes were the number of participants with: 1. at least one adenoma, 2. more than one adenoma, 3. at least one adenoma greater than or equal to 1 cm, or 4. a new diagnosis of CRC. The secondary outcome was the number of adverse events.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data, assessed trial quality and resolved discrepancies by consensus. We used risk ratios (RR) and risk difference (RD) with 95% confidence intervals (CI) to measure the effect. If statistical significance was reached, we reported the number needed to treat for an additional beneficial outcome (NNTB) or harmful outcome (NNTH). We combined the study data using the fixed-effect model if it was clinically, methodologically, and statistically reasonable.

MAIN RESULTS

We included seven studies, of which five studies with 4798 participants provided data for analyses in this review. The mean ages of the participants ranged from 56 to 66 years. All participants had a history of adenomas, which had been removed to achieve a polyp-free colon at baseline. The interventions were wheat bran fibre, ispaghula husk, or a comprehensive dietary intervention with high fibre whole food sources alone or in combination. The comparators were low-fibre (2 to 3 g per day), placebo, or a regular diet. The combined data showed no statistically significant difference between the intervention and control groups for the number of participants with at least one adenoma (5 RCTs, n = 3641, RR 1.04, 95% CI 0.95 to 1.13, low-quality evidence), more than one adenoma (2 RCTs, n = 2542, RR 1.06, 95% CI 0.94 to 1.20, low-quality evidence), or at least one adenoma 1 cm or greater (4 RCTs, n = 3224, RR 0.99, 95% CI 0.82 to 1.20, low-quality evidence) at three to four years. The results on the number of participants diagnosed with colorectal cancer favoured the control group over the dietary fibre group (2 RCTS, n = 2794, RR 2.70, 95% CI 1.07 to 6.85, low-quality evidence). After 8 years of comprehensive dietary intervention, no statistically significant difference was found in the number of participants with at least one recurrent adenoma (1 RCT, n = 1905, RR 0.97, 95% CI 0.78 to 1.20), or with more than one adenoma (1 RCT, n = 1905, RR 0.89, 95% CI 0.64 to 1.24). More participants given ispaghula husk group had at least one recurrent adenoma than the control group (1 RCT, n = 376, RR 1.45, 95% CI 1.01 to 2.08). Other analyses by types of fibre intervention were not statistically significant. The overall dropout rate was over 16% in these trials with no reasons given for these losses. Sensitivity analysis incorporating these missing data shows that none of the results can be considered as robust; when the large numbers of participants lost to follow-up were assumed to have had an event or not, the results changed sufficiently to alter the conclusions that we would draw. Therefore, the reliability of the findings may have been compromised by these missing data (attrition bias) and should be interpreted with caution.

AUTHORS' CONCLUSIONS

There is a lack of evidence from existing RCTs to suggest that increased dietary fibre intake will reduce the recurrence of adenomatous polyps in those with a history of adenomatous polyps within a two to eight year period. However, these results may be unreliable and should be interpreted cautiously, not only because of the high rate of loss to follow-up, but also because adenomatous polyp is a surrogate outcome for the unobserved true endpoint CRC. Longer-term trials with higher dietary fibre levels are needed to enable confident conclusion.

Pharmacotherapy for inherited colorectal cancer

IMPORTANCE OF THE FIELD

An important recent consideration in the medical management of colorectal cancer risk has been the notion of primary prevention or 'chemoprevention' of adenomas. A number of promising agents, and even combinations of agents, have shown promise in clinical trials. This review is written in the interest of capturing the current state of chemoprevention in familial adenomatous polyposis (FAP). This will take a decidedly clinical perspective.

AREAS COVERED IN THIS REVIEW

This review addresses mainly randomized clinical chemoprevention trials. A search using PubMed from 1980 to present was conducted.

WHAT THE READER WILL GAIN

The reader should gain an appreciation of the role that chemoprevention clinical trials in FAP has had in establishing a basis for clinically oriented use of selected drugs, mainly sulindac and celecoxib, as adjuncts to surgical and endoscopic treatment. In addition, the reader will see how FAP trials can provide a foundation for similar trials in nonfamilial adenomas.

TAKE-HOME MESSAGE

As a proving ground for new, potential chemopreventive agents, trials in FAP involved short-term (3- to 12-month) administration of drug. Endpoints generally involved measures of adenoma regression in the rectal segment retained post-colectomy.

Advances in dietary fibre characterisation. 2. Consumption, chemistry, physiology and measurement of resistant starch; implications for health and food labelling

Resistant starch (RS) is defined as ‘the sum of starch and products of starch degradation not absorbed in the small intestine of healthy individuals’. This basic definition includes different types of starches that (1) are physically inaccessible, usually due to an encapsulation in intact cell walls, or (2) are naturally highly resistant to mammalian α-amylase, or (3) have been modified by hydrothermic treatments then retrograded. Interest in RS has increased significantly during the last two decades, mostly due to its capacity to produce a large amount of butyrate all along the colon. Butyrate has been observed to have a range of effects on cell metabolism, differentiation and cell growth as well as inhibition of a variety of factors that underlie the initiation, progression and growth of colon tumours. The physiological definition of RS, which seems to be nearly consensual, raises a difficulty in proper analytical quantification of RS. A number of methods have, however, been proposed and provide similar values for the RS content in most of the starch types and starchy foods. It seems, however, that some starches, proven to be partly resistant according toin vivoinvestigations on ileostomy subjects, could not be quantified by most of these methods. This may be due to a widespread use of glucoamylase during the first steps of these methods. Accordingly, there is an international debate on health aspects of RS and on how to quantify the RS content of food products. The present review describes aspects of classification of RS, past and current consumption, physiological effects and analytical aspects, and concludes with impacts on food and product labelling.

Non steroidal anti-inflammatory drugs (NSAID) and Aspirin for preventing colorectal adenomas and carcinomas

EDITORIAL NOTE

This review was split in 2012 and the review question was to be addressed according to three new protocols: (See: http://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD010267.pub2; http://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD010291.pub2; http://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD010325.pub2). These titles were withdrawn at the protocol stage in 2020 as the authors did not make any progress on the reviews. This original review will no longer be updated and may be superseded by new titles hosted by Cochrane Gut in the future.

BACKGROUND

There is evidence from experimental animals studies, prospective and retrospective observational studies that nonsteroidal anti-inflammatory drugs (NSAIDS) may reduce the development of sporadic colorectal adenomas (CRAs) and cancer (CRC) and may induce the regression of adenomas in familial adenomatous polyposis (FAP).

OBJECTIVES

To conduct a systematic review to determine the effect of NSAIDS for the prevention or regression of CRAs and CRC.

SEARCH STRATEGY

Randomized controlled trials (RCTs) up to September 2003 were identified.

SELECTION CRITERIA

NSAIDS and aspirin (ASA) were the interventions. The primary outcomes were the number of subjects with at least one CRA, the change in polyp burden, and CRC. The secondary outcome was adverse events.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data and assessed trial quality. Dichotomous outcomes were reported as relative risks (RR) with 95% confidence intervals (CI). The data were combined with the random effects model if clinically and statistically reasonable.

MAIN RESULTS

Nine trials with 150 familial adenomatous polyposis (FAP) and 24,143 population subjects met the inclusion criteria. The interventions included sulindac, celecoxib, or aspirin (ASA). From the combined results of three trials, significantly fewer subjects in the low dose ASA group developed recurrent sporadic CRAs [RR 0.77 (95% CI 0.61, 0.96), (NNT 12.5 (95% CI 7.7, 25)] after one to three years. In another three trials, phenotypic FAP subjects that received sulindac or celecoxib had a greater proportional reduction (range: 11.9% to 44%) in the number of CRAs compared to those in the control group (range: 4.5% to 10%). There was no significant difference for the outcomes of CRC or adverse events in any of the trials.

REVIEWERS' CONCLUSIONS

There was evidence from three pooled RCTs that ASA significantly reduces the recurrence of sporadic adenomatous polyps after one to three years. There is evidence from short-term studies to support regression, but not elimination or prevention of CRAs in FAP.

Changing concepts of dietary fiber: implications for carcinogenesis

The dietary fiber (DF) hypothesis suggested that DF, as plant cell walls, protected against colorectal cancer. The implicit assumption in much historic literature was that the readily analyzed and quantified nonstarch polysaccharide (NSP) component was critical in cancer protection. However, the presence of polymeric phenolic components such as lignin or suberin has profound effects on the physicochemical properties of the cell walls and largely determines their physiological properties in humans. In certain groups of food plants, degradation of cell walls that contain neither lignin nor suberin releases ferulic acid and other hydroxycinnamic acids. These acids have antioxidant, antimutagenic, and other anticancer effects, including modulation of gene expression and immune response. Reexamination of literature on cancer protection suggests that plant cell walls containing significant amounts of phenolic components may be the most likely to protect against cancer. In the last 30 years, the definition of DF has been incrementally expanded to incorporate NSP extracted from plant cell walls and from sources other than plant cell walls, then resistant starch, and most recently nondigestible oligosaccharides. On the early definitions, increased consumption of DF could only be achieved by increasing the intake of whole grains, brans, or other food plant material that would increase the intake of plant cell walls containing significant amounts of phenolic components. However, the new definitions make it possible to increase "dietary fiber" without consuming any such materials. We suggest that this could have negative connotations for cancer risk in human populations.

The role of eicosanoids, cyclooxygenases, and nonsteroidal anti-inflammatory drugs in colorectal tumorigenesis and chemoprevention

There is mounting evidence from studies on experimental cancer in rodents, interventional studies in patients with familial adenomatous polyposis, and some, but not all, epidemiologic investigations, that suggests a chemopreventive effect of aspirin and nonaspirin nonsteroidal anti-inflammatory drugs (NSAIDs) against colorectal cancer. In addition, the mechanisms by which these agents modulate tumorigenesis are being elucidated in laboratory experiments. Currently available NSAIDs are unlikely to have an acceptable benefit-to-risk ratio for long-term use in an asymptomatic population. Once the discrete chemopreventive mechanisms are established and the genetic background and risk factor profile of individuals who will benefit from chemoprevention are clarified, a low-dose combination of NSAIDs with different targets may optimize efficacy and minimize toxicity. At present, however, colectomy is still the treatment of choice for patients with familial adenomatous polyposis, and early screening and regular surveillance colonoscopies are the choices for those at risk for hereditary nonpolyposis colorectal cancer. In the average-risk individual, endoscopic screening and surveillance will remain the core of efforts to prevent sporadic colorectal cancer.

Dietary fibre for the prevention of colorectal adenomas and carcinomas

BACKGROUND

Colorectal cancer (CRC) is a major cause of morbidity and mortality in industrialized countries. Experimental evidence has supported the hypothesis that dietary fibre may be protective for the development of CRC, although epidemiologic data have been inconclusive.

OBJECTIVES

We have conducted a systematic review and meta-analysis to assess the effect of dietary fibre on the incidence or recurrence of colorectal adenomas, the incidence of CRC, and the development of adverse events.

SEARCH STRATEGY

We identified randomized controlled trials from Medline, Embase, and the Cochrane Controlled Trials Register up to Oct 2001

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials were assessed. The population included all subjects that had adenomatous polyps but no previous history of colorectal cancer (CRC), a documented "clean colon" at baseline and repeated visualization of the colon/rectum after at least two years of follow-up. Dietary fibre was the intervention. The primary outcomes were the number of subjects with: a) at least one adenoma, b) more than one adenoma, c) at least one adenoma greater than or equal to 1 cm or d) a new diagnosis of CRC. The secondary outcome was the number of adverse events.

DATA COLLECTION AND ANALYSIS

Two reviewers independently extracted data, assessed trial quality and resolved discrepancies by consensus. The outcomes were reported as relative risks (RR) and risk difference (RD) with 95% confidence intervals (CI). If statistical significance was reached, the number need to treat (NNTT) or harm (NNTH) was reported. The study data were combined with the fixed effects model if it was clinically, methodologically, and statistically reasonable.

MAIN RESULTS

Five studies with 4349 subjects met the inclusion criteria. The interventions were wheat bran fibre, ispaghula husk, or a comprehensive dietary intervention with high fibre whole food sources alone or in combination. When the data were combined there was no difference between the intervention and control groups for the number of subjects with at least one adenoma [RR 1.04 (95% CI 0.95,1.13); RD 0.01 (95% CI 0.02,0.04)]. As well, the combined results for the number of subjects with more than one adenoma [RR 1.02 (95% CI 0.89,1.17), RD 0.00 (-0.02,0.03)] or at least one adenoma 1 cm or greater [RR 0.94 (95% CI 0.77,1.15), RD -0.01 (-0.02,0.01)] were not statistically significant. Other primary and secondary outcomes and subanalyses by type of fibre intervention were not statistically or clinically significant.

REVIEWER'S CONCLUSIONS

There is currently no evidence from RCTs to suggest that increased dietary fibre intake will reduce the incidence or recurrence of adenomatous polyps within a two to four year period.

Cancer genetics in oncology practice

Cancer is a genetic disease caused by the progressive accumulation of mutations in critical genes that control cell growth and differentiation. Completion of the Human Genome Project promises to revolutionize the practice of Medicine, especially Oncology care. The tremendous gains in the knowledge of the structure and function of human genes will surely impact the diagnosis, prognosis and treatment of cancer. Moreover, it will lead to more effective cancer control through the use of genetics to quantify individual cancer risks. This article reviews the current status of genetic testing and counseling for cancer risk assessment and will suggest a framework for integrating such counseling into oncology practice.

Comparative effects of three resistant starch preparations on transit time and short-chain fatty acid production in rats

A high-fiber diet may protect against colon cancer because of the butyrate generated in the colon by bacterial fermentation of nonstarch polysaccharides. Butryrate can reverse neoplastic changes, at least in vitro, and resistant starch (RS) represents a source of butyrate in vivo. We examined the effects of replacing normal maize starch in the diet of rats with three preparations of RS on the amounts of starch, butyrate, and other short-chain fatty acids in the cecum. We examined the effects on fecal bulking and transit time, which have been suggested to protect against colon cancer. The RS preparations that we tested were potato starch, high-amylose maize starch, and an alpha-amylase-treated high-amylose maize starch. All had major effects on fecal weight and on the weight of the cecum but only slightly shortened transit times. All increased the amount of starch reaching the cecum and increased short-chain fatty acid production in the cecum; potato starch had the greatest effect and high-amylose maize starch the least. Potato starch, unlike high-amylose maize starch, enhanced the proportion of butyrate. Thus there were marked differences among sources of RS, even though these were all classified as RS2. The significance for colon cancer is discussed.

[Aspirin against cancer]

PURPOSE

That aspirin as an anti-aggregative and anti-inflammatory compound might prevent tumor spread is an old concept that is still not of clinical relevance. To date, aspirin has been shown in several epidemiologic studies to be linked with a reduction of colorectal cancer incidence, as well as the incidence of lung and breast cancer. In this issue, we have summarized the mechanisms that support this hypothesis, and we have analysed the main clinical studies.

RESULTS

Only case-control studies and most of the prospective cohort studies showed a reduction of colorectal cancer incidence in regular aspirin users. Nevertheless, the minimum effective doses of aspirin and the duration of therapy remain unclear. To date, only one prospective randomized trial has evaluated the influence of aspirin in the prevention of colorectal cancer. Despite the inclusion of 22,000 subjects and a five-year follow-up, aspirin failed to show any protection. The mechanism of the potential role of aspirin in preventing cancer, primarily supposed to rely on the antiprostaglandin effect, is now under debate. Few studies have evaluated the prevention of other cancers, such as breast or lung cancers, by aspirin. Data remain too sparse to allow any conclusion.

CONCLUSION

The role of aspirin in the prevention of colorectal cancer still needs further studies, such as a prospective randomized study, which should be conducted in a high-risk population.

Upper gastrointestinal disease in patients with familial adenomatous polyposis

BACKGROUND

Upper gastrointestinal disease has become an important aspect in the management of patients with familial adenomatous polyposis (FAP).

METHODS

A review of the literature was carried out using Medline. Epidemiology, pathology and treatment options are considered.

RESULTS AND CONCLUSION

Despite the fact that over 90 per cent of patients with FAP develop duodenal adenomas, only 5 per cent go on to develop cancer. In the absence of methods to detect who is at risk of cancer, all patients undergo regular endoscopic surveillance at present. Chemoprevention in the form of drug therapy may be the answer to controlling the disease.