The adenoma-carcinoma sequence and prospects for the prevention of colorectal neoplasia

Association of the triglyceride-glucose index with the occurrence and recurrence of colorectal adenomas: a retrospective study from China

BACKGROUND

Resection of colorectal adenoma (CRA) prevents colorectal cancer; however, recurrence is common. We aimed to assess the association of the triglyceride-glucose (TyG) index with CRA occurrence and recurrence.

METHODS

Data from 3392 participants at a hospital in China from 2020 to 2022 were analyzed. Logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). A restricted cubic spline was used to fit TyG index dose‒response curves to recurrent adenomas. The discriminatory power of TyG index for predicting later recurrence was assessed with the area under the receiver operating characteristic (ROC) curve in 170 patients with a TyG index at initial adenoma diagnosis.

RESULTS

One thousand five hundred ninety-six adenoma and 1465 normal participants were included in the occurrence analysis, and 179 recurrent and 152 nonrecurrent participants were included in the recurrence analysis. The TyG mutation was an independent risk factor for CRA occurrence and recurrence. After adjusting for confounders, the risk of adenoma in the participants in Q2, Q3, and Q4 groups of TyG was 1.324 (95% CI 1.020-1.718), 1.349 (95% CI 1.030-1.765), and 1.445 (95% CI 1.055-1.980) times higher than that of the Q1, respectively, and the risk of recurrence in the Q3 and Q4 groups was 2.267 (95% CI 1.096-4.691) and 2.824 (95% CI 1.199-6.648) times in Q1 group. Multiple logistic regression showed that the highest quartile of the TyG index was associated with a greater risk of advanced adenoma recurrence (OR 4.456, 95% CI 1.157-17.164), two or more adenomas (OR 5.079, 95% CI 1.136-22.714 [after removal of TyG index extreme values]), and proximal colon or both adenomas (OR 3.043, 95% CI 1.186-7.810). Subgroup analysis revealed that the association was found to be present only in participants of all age groups who were either male or without obesity, hyperglycemia, hypertension, or dyslipidemia (p < 0.05). ROC curves illustrated that the TyG index had good predictive efficacy for identifying recurrence, especially for patients with two or more adenomas (AUC 0.777, 95% CI 0.648-0.907).

CONCLUSIONS

An increase in the TyG index is associated with an increased risk of adenoma occurrence and recurrence, with a stronger association with the latter.

A comprehensive systematic review of colorectal cancer screening clinical practices guidelines and consensus statements

High-quality clinical practice guidelines (CPGs) and consensus statements (CSs) are essential for evidence-based medicine. The purpose of this systematic review was to appraise the quality and reporting of colorectal cancer (CRC) screening CPGs and CSs. After prospective registration (Prospero no: CRD42021286156), a systematic review searched CRC guidances in duplicate without language restrictions in ten databases, 20 society websites, and grey literature from 2018 to 2021. We appraised quality with AGREE II (% of maximum score) and reporting with RIGHT (% of total 35 items) tools. Twenty-four CPGs and 5 CSs were analysed. The median overall quality and reporting were 54.0% (IQR 45.7-75.0) and 42.0% (IQR 31.4-68.6). The applicability had low quality (AGREE II score <50%) in 83% of guidances (24/29). Recommendations and conflict of interest were low-reported (RIGHT score <50%) in 62% guidances (18/29) and 69% (20/29). CPGs that deployed systematic reviews had better quality and reporting than CSs (AGREE: 68.5% vs. 35.5%; p = 0.001; RIGHT: 74.6% vs. 41.4%; p  =  0.001). In summary, CRC screening CPGs and CSs achieved low quality and reporting. It is necessary a revision and an improvement of the current guidances. Their development should apply a robust methodology using proper guideline development tools to obtain high-quality evidence-based documents.

Systematic review of shared decision-making in guidelines about colorectal cancer screening

INTRODUCTION

We aimed to systematically evaluate quality of shared decision-making (SDM) in colorectal cancer (CRC) screening clinical practice guidelines (CPGs) and consensus statements (CSs).

METHODS

Search for CRC screening guidances was from 2010 to November 2021 in EMBASE, Web of Science, MEDLINE, Scopus and CDSR, and the World Wide Web. Three independent reviewers and an arbitrator rated the quality of each guidance using a SDM quality assessment tool (maximum score: 31). Reviewer agreement was 0.88.

RESULTS

SDM appeared in 41/83 (49.4%) CPGs and 9/19 (47.4%) CSs. None met all the quality criteria, and 51.0% (52/102) failed to meet any quality items. Overall compliance was low (mean 1.63, IQR 0-2). Quality was better in guidances published after 2015 (mean 1, IQR 0-3 vs. mean 0.5, IQR 0-1.5; p = 0.048) and when the term SDM was specifically reported (mean 4.5, IQR 2.5-4.5 vs. mean 0.5, IQR 0-1.5; p < 0.001). CPGs underpinned by systematic reviews showed better SDM quality than consensus (mean 1, IQR 0-3 vs. mean 0, IQR 0-2, p = 0.040).

CONCLUSION

SDM quality was suboptimal and mentioned in less than half of the guidances, and recommendations were scarce. Guideline developers should incorporate evidence-based SDM recommendations in guidances to underpin the translation of evidence into practice.

Risk of adenoma recurrence after polypectomy in patients younger than 50 years vs. 50 years old and over with diminutive or small adenomas

Background and aims

Current studies have shown that polyp recurrence occurs after colonic adenomas polypectomy (AP), but the difference in recurrence risk between patients in patients older than 50 years and younger than 50 years has not been clearly studied.

Methods

490 patients after AP were enrolled in the study. The patients were classified according to age (&lt;50 years old or ≥50 years old), and then further categorized according to the baseline adenoma characteristics: Group 1: 1–2 non-advanced adenomas (NAAs) 1–5 mm in size; Group 2: ≥3 NAAs, 1–5 mm; Group 3: 1–2 NAAs, 6–9 mm; Group 4: ≥3 NAAs, 6–9 mm; and Group 5: advanced adenomas.

Results

During a mean follow-up interval of 2.52 years (2.51 years for ≥50 years old and 2.55 years for patients &lt;50 years old), NAA recurrence was detected in 147 patients (30.0%). Overall, the hazard ratio (HR) for NAA recurrence after AP was higher in patients ≥50 years old than that in patients &lt;50 years old (HR, 1.774, P = 0.003). For patients &lt;50 years old, HRs (Group 2-5 vs. G1, respectively) for NAA recurrence were 0.744 (P = 0.773), 3.885 (P = 0.007), 5.337 (P = 0.003), and 3.334 (P = 0.015). For patients ≥50 years old, HRs (Group 2-5 vs. G1, respectively) for NAA recurrence were 1.033 (P = 0.965), 1.250 (P = 0.405), 2.252 (P = 0.015), and 1.887 (P = 0.009). For G1, the risk of NAA recurrence was significantly higher in patients ≥50 years old (HR, 2.932, P = 0.011) than that in patients &lt;50 years old; for G2–G5, the risk was similar in the two age groups (P &gt; 0.05).

Conclusions

For patients &lt;50 years old with less than 3 NAAs that are 1–5 mm in size, the recurrence rate of NAA is less than that of patients ≥50 years old with the same index colonoscopy findings. When the adenomas are ≥5 mm, or their number exceeds 3, they have similar recurrence risk as that for patients ≥50 years old.

A prospective cohort study of the relationship between the withdrawal time and the detection rate of colorectal adenoma

BACKGROUND AND AIMS

The effect of colonoscopy withdrawal time (WT) beyond 6 min on colorectal adenoma detection rate (ADR) is unclear. We focused on the relationship between WT and ADR.

MATERIALS AND METHODS

This study was a prospective observational study involving 437 patients who underwent colonoscopy at Tongren Hospital in Shanghai from 1 July 2020 to 31 August 2020. Patients were divided into two groups according to whether the WT was >6 min. Age, sex, body mass index (BMI), defoaming rate score, Boston bowel preparation scale (BBPS), primary colonoscopy, hypertension, diabetes mellitus, dietary preparation 1 day before the examination, and abdominal surgery history factors were analysed by univariate and multivariable logistic regression to explore the odds ratios (ORs) of ADR in two WT groups. Restricted cubic spline regression was used to further analyze the relationship between WT and the ORs of adenoma detection.

RESULTS

The ADR among 437 patients was 17.16% (75/437). Multivariable regression analysis showed that in the group with WT >6 min, patients aged ≥50 years old and male could have an increased risk of adenoma detection (OR 5.80, 95% CI 2.32-14.47; p < .001; OR 2.30, 95% CI 1.19-4.43; p = .013). The cubic spline curve showed that the ADR increased with time for WT of 6-8 min, and the highest ADR was achieved when the WT was controlled at 8 min (WT = 5.997, OR = 0.997; WT = 8.240 min, OR = 3.092).

CONCLUSION

The highest ADR was achieved when the WT of colonoscopy was controlled at 8 min.

Fecal Enterotoxigenic Bacteroides fragilis-Peptostreptococcus stomatis-Parvimonas micra Biomarker for Noninvasive Diagnosis and Prognosis of Colorectal Laterally Spreading Tumor

Objective

Up to now, non-invasive diagnosis of laterally spreading tumor (LST) and prediction of adenoma recurrence after endoscopic resection of LSTs is inevitable. This study aimed to identify a microbial signature with clinical significance of diagnosing LSTs and predicting adenoma recurrence after LSTs colectomy.

Methods

We performed 16S rRNA sequencing in 24 mucosal samples, including 5 healthy controls (HC), 8 colorectal adenoma (CRA) patients, and 11 LST patients. The differentiating microbiota in fecal samples was quantified by qPCR in 475 cases with 113 HC, 208 CRA patients, 109 LST patients, and 45 colorectal cancer (CRC) patients. We identified differentially abundant taxa among cases and controls using linear discriminant analysis effect size analysis. ROC curve was used to evaluate diagnostic values of the bacterial candidates. Pairwise comparison of AUCs was performed by using the Delong's test. The Mantel-Haenszel hazard models were performed to determine the effects of microbial compositions on recurrence free survival.

Results

The microbial dysbiosis of LST was characterized by relative high abundance of the genus Lactobacillus-Streptococcus and the species enterotoxigenic Bacteroides fragilis (ETBF)-Peptostreptococcus stomatis (P. stomatis)-Parvimonas micra (P. micra). The abundance of ETBF, P. stomatis, and P. micra were steadily increasing in LST and CRC groups. P. stomatis behaved stronger value on diagnosing LST than the other two bacteria (AUC 0.887, 95% CI 0.842-0.931). The combination of P. stomatis, P. micra, and ETBF (AUC 0.922, 95% CI 0.887-0.958) revealed strongest diagnostic power with 88.7% sensitivity and 81.4% specificity. ETBF, P. stomatis, and P. micra were associated with malignant LST (P_P.stomatis = 0.0015, P_P.micra = 0.0255, P_ETBF = 0.0169) and the abundance of IL-6. The high abundance of P. stomatis was related to the adenoma recurrence after LST resection (HR = 3.88, P = 0.008).

Conclusions

Fecal microbiome signature (ETBF-P. stomatis-P. micra) can diagnose LSTs with high accuracy. ETBF, P. stomatis, and P. micra were related to malignant LST and P. stomatis exhibited high predictive value on the adenoma recurrence after resection of LSTs. The fecal microbiome signature of LST may provide a noninvasive alternative to early detect LST and predict the adenoma recurrence risk after resections of LSTs.

ACG Clinical Guidelines: Colorectal Cancer Screening 2021

Colorectal cancer (CRC) is the third most common cancer in men and women in the United States. CRC screening efforts are directed toward removal of adenomas and sessile serrated lesions and detection of early-stage CRC. The purpose of this article is to update the 2009 American College of Gastroenterology CRC screening guidelines. The guideline is framed around several key questions. We conducted a comprehensive literature search to include studies through October 2020. The inclusion criteria were studies of any design with men and women age 40 years and older. Detailed recommendations for CRC screening in average-risk individuals and those with a family history of CRC are discussed. We also provide recommendations on the role of aspirin for chemoprevention, quality indicators for colonoscopy, approaches to organized CRC screening and improving adherence to CRC screening. CRC screening must be optimized to allow effective and sustained reduction of CRC incidence and mortality. This can be accomplished by achieving high rates of adherence, quality monitoring and improvement, following evidence-based guidelines, and removing barriers through the spectrum of care from noninvasive screening tests to screening and diagnostic colonoscopy. The development of cost-effective, highly accurate, noninvasive modalities associated with improved overall adherence to the screening process is also a desirable goal.

Berberine versus placebo for the prevention of recurrence of colorectal adenoma: a multicentre, double-blinded, randomised controlled study

BACKGROUND

Chemoprevention of colorectal adenoma and colorectal cancer remains an important public health goal. The present study aimed to investigate the clinical potential and safety of berberine for prevention of colorectal adenoma recurrence.

METHODS

This double-blind, randomised, placebo-controlled trial was done in seven hospital centres across six provinces in China. Individuals aged 18-75 years who had at least one but no more than six histologically confirmed colorectal adenomas that had undergone complete polypectomy within the 6 months before recruitment were recruited and randomly assigned (1:1) to receive berberine (0·3 g twice daily) or placebo tablets via block randomisation (block size of six). Participants were to undergo a first follow-up colonoscopy 1 year after enrolment, and if no colorectal adenomas were detected, a second follow-up colonoscopy at 2 years was planned. The study continued until the last enrolled participant reached the 2-year follow-up point. All participants, investigators, endoscopists, and pathologists were blinded to treatment assignment. The primary efficacy endpoint was the recurrence of adenomas at any follow-up colonoscopy. Analysis was based on modified intention-to-treat, with the full analysis set including all randomised participants who received at least one dose of study medication and who had available efficacy data. The study is registered with ClinicalTrials.gov, number NCT02226185; the trial has ended and this report represents the final analysis.

FINDINGS

Between Nov 14, 2014, and Dec 30, 2016, 553 participants were randomly assigned to the berberine group and 555 to the placebo group. The full analysis set consisted of 429 participants in the berberine group and 462 in the placebo group. 155 (36%) participants in the berberine group and 216 (47%) in the placebo group were found to have recurrent adenoma during follow-up (unadjusted relative risk ratio for recurrence 0·77, 95% CI 0·66-0·91; p=0·001). No colorectal cancers were detected during follow-up. The most common adverse event was constipation (six [1%] of 446 patients in the berberine group vs one [<0·5%] of 478 in the placebo group). No serious adverse events were reported.

INTERPRETATION

Berberine 0·3 g twice daily was safe and effective in reducing the risk of recurrence of colorectal adenoma and could be an option for chemoprevention after polypectomy.

FUNDING

National Natural Science Foundation of China.

Dietary n-3/long-chain n-3 polyunsaturated fatty acids for prevention of sporadic colorectal tumors: a randomized controlled trial in polypectomized participants

To address preventive effects of n-3 PUFAs/LC n-3 PUFAs on CRTs, a randomized controlled trial was conducted. One-hundred four experimental group participants were advised to increase intake of n-3 PUFAs, including fish/shell fish, fish oil supplements and perilla oils, and to decrease consumption of n-6 PUFAs and fats/oils as a whole for 24 months. One-hundred one control group participants were only cautioned to reduce consumption of fats/oils as a whole. Random allocation was satisfactorily attained, and participants sufficiently complied with our regimen. Intakes, plasma concentrations, and compositions of the RBC and sigmoid colon membranes of n-3 PUFAs, LC n-3 PUFAs, EPA and DHA increased, and the ratios of n-6 PUFAs/n-3 PUFAs and AA/LC n-3 PUFAs decreased without any adverse response. Twenty-four months after the intervention, the multivariate-adjusted hazard ratio (95% confidence intervals) was estimated to be 0.805 (0.536-1.209) with a signal towards the reduced CRT incidence.

Consensus on the Prevention, Screening, Early Diagnosis and Treatment of Colorectal Tumors in China: Chinese Society of Gastroenterology, October 14-15, 2011, Shanghai, China

BACKGROUND

Colorectal cancer (CRC) is steadily increasing in China. Colorectal adenoma (CRA) is the most important precancerous disease of CRC. Screening for colorectal tumors can aid early diagnosis. Advances in endoscopic mucosal resection and endoscopic submucosal dissection can aid the early treatment of colorectal tumors. Furthermore, because of high risk of recurrence after removal of adenomas under endoscopy, factors contributing to recurrence, the follow-up mode and the interval established, and the feasibility of application and the time of various chemical preventions should be concerned. However, a relevant consensus on the screening, early diagnosis and treatment, and prevention of colorectal tumors in China is lacking.

SUMMARY

The consensus recommendations include epidemiology, pathology, screening, early diagnosis, endoscopic treatment, monitoring and follow-up, and chemoprevention of colorectal tumors in China.

KEY MESSAGE

This is the first consensus on the prevention, screening, early diagnosis and treatment of CRA and CRC in China based on evidence in the literature and on local data.

PRACTICAL IMPLICATIONS

Through reviewing the literature, regional data and passing the consensus by an anonymous vote, gastroenterology experts from all over China launch the consensus recommendations in Shanghai. The incidence and mortality of CRC in China has increased, and the incidence or detection rate of CRA has increased rapidly. Screening for colorectal tumors should be performed at age 50-74 years. Preliminary screening should be undertaken to find persons at high risk, followed by colonoscopy. A screening cycle of 3 years is recommended for persistent interventions. Opportunistic screening is a mode suitable for the current healthcare system and national situation. Colonoscopy combined with pathological examination is the standard method for the diagnosis of colorectal tumors. CRA removal under endoscopy can prevent CRC to some extent, but CRA has an obvious recurrence trend. The follow-up interval after the removal or surgery of colorectal tumors should be different with lesions. Primary prevention of CRA includes improved diet with more fiber, supplements containing calcium and vitamin D, supplements containing folic acid for those with low hemoglobin levels, and cessation of tobacco smoking. Non-steroidal anti-inflammatory drugs and selective cyclooxygenase-2 inhibitors have been recognized to prevent recurrence after adenoma removal.

Methionine synthase A2756G polymorphism and risk of colorectal adenoma and cancer: evidence based on 27 studies

Methionine synthase (MTR), which plays a central role in maintaining adequate intracellular folate, methionine and normal homocysteine concentrations, was thought to be involved in the development of colorectal cancer (CRC) and colorectal adenoma (CRA) by affecting DNA methylation. However, studies on the association between MTR A2756G polymorphism and CRC/CRA remain conflicting. We conducted a meta-analysis of 27 studies, including 13465 cases and 20430 controls for CRC, and 4844 cases and 11743 controls for CRA. Potential sources of heterogeneity and publication bias were also systematically explored. Overall, the summary odds ratio of G variant for CRC was 1.03 (95% CI: 0.96-1.09) and 1.05 (95% CI: 0.99-1.12) for CRA. No significant results were observed in heterozygous and homozygous when compared with wild genotype for these polymorphisms. In the stratified analyses according to ethnicity, source of controls, sample size, sex, and tumor site, no evidence of any gene-disease association was obtained. Results from the meta-analysis of four studies on MTR stratified according to smoking and alcohol drinking status showed an increased CRC risk in heavy smokers (OR = 2.06, 95% CI: 1.32-3.20) and heavy drinkers (OR = 2.00, 95% CI: 1.28-3.09) for G allele carriers. This meta-analysis suggests that the MTR A2756G polymorphism is not associated with CRC/CRA susceptibility and that gene-environment interaction may exist.

Whole blood viscosity issues VI: Association with blood salicylate level and gastrointestinal bleeding

Background:

This series on whole blood viscosity issues has been trying to elucidate the sensitivity, specificity and usefulness of the laboratory parameter in clinical practice. The postulation has been that since antiplatelet is used in the management of stasis, of which blood viscosity is an index, the latter would be useful laboratory indication and/or contraindication.

Aim:

The aim of this study was to observe whether blood level of acetylsalicylic acid differs with the level of whole blood viscosity.

Patients and Methods:

Out of the ten years database, 538 cases that were concomitantly tested for haematocrit, total proteins and blood level of salicylate were selected for this study. A separate nine cases of positive faecal occult blood tests were audited for blood viscosity and reviewed.

Results:

A statistically significant difference is observed with lower blood viscosity being associated with higher salicylate level in comparison of the former between the highest vs. lowest quartiles (p < 0.002). This observation demonstrates the effect of aspirin in lowering blood stasis. Reviewing the positive faecal occult blood cases indicate that gastrointestinal bleeding is characterized by relative hypoviscosity and that hyperviscosity is not present during bleeding complications.

Conclusion:

The findings affirm that whole blood viscosity is a valid clinical laboratory parameter for evidence-based contraindication, indication and monitoring of antiplatelet medication. It calls for better appreciation and clinical utility of whole blood viscosity, which (in the absence of viscometer) can now be extrapolated from haematocrit and total proteins.

Clinical significance of serum levels of IGF-1 and IGFBP-3 in patients with colorectal adenoma

AIM: To investigate the clinical significance of serum levels of IGF-1 and IGFBP-3 in patients with colorectal adenoma.

METHODS: Blood samples collected from 120 patients with colorectal adenoma (CRA), 48 patients with colorectal cancer (CRC) and 34 healthy controls were used to determine serum levels of IGF-l and IGFBP-3 by radioimmunoassay (RIA) and immunoradiometric assay (IRMA), respectively.

RESULTS: Serum levels of IGF-1 and IGF-1/IGFBP-3 ratio in the CRC group (247.35 ± 60.77; 0.063 ± 0.010) and CRA group (224.75 ± 69.45; 0.055 ± 0.010) were significantly higher than those in the healthy control group (195.39 ± 63.37; 0.047 ± 0.013) (both P < 0.05). Serum IGF-1, IGFBP-3, and IGF-1/IGFBP-3 ratio in CRA showed no significant association with gender, age, history of smoking and drinking, family history of cancer, and the size, number, site or histological classification of polyps. Serum levels of IGF-1 and IGF-1/IGFBP-3 ratio in the CRC group (247.35 ± 60.77; 0.063 ± 0.010) and high-risk CRA group (235.81 ± 73.72; 0.056 ± 0.011) were significantly higher than those in the advanced CRA group (208.15 ± 59.44; 0.052 ± 0.008) (all P < 0.05). There was a positive correlation between serum levels of IGF-1 and IGFBP-3 in CRA (r = 0.796, P < 0.001).

CONCLUSION: High serum levels of IGF-1 and IGF-1/ IGFBP-3 may play a role in the malignant transformation of colorectal adenoma, and detection of them can be used to screen precancerous lesions.

Reappraisal of the options for colorectal cancer screening in England

AIM

The aim was to use newly available data to estimate the cost effectiveness and endoscopy requirements of screening options for colorectal cancer (CRC) to inform screening policy in England.

METHODS

A state transition model simulated the life experience of a cohort of individuals in the general population of England with normal colon/rectal epithelium through to the development of adenomas and CRC and subsequent death. CRC natural history model parameters and screening test characteristics were estimated simultaneously by a process of model calibration. This process was fitted to observed data on CRC incidence in the absence of screening, data from existing screening programmes, and data from the UK flexible sigmoidoscopy (FS) screening trial. The costs, effects and resource impact were evaluated for a range of screening options involving the guaiac or immunochemical faecal occult blood test (gFOBT/iFOBT) and FS.

RESULTS

The model suggests that screening strategies involving FS or iFOBT may produce additional benefits compared with the current policy of biennial gFOBT for 60-74-year-olds. The age at which a single FS screen results in the greatest quality-adjusted life year gain was 55, with similar gains for ages between 52 and 58. Strategies which combined FS and iFOBT showed further benefits and improved economic outcomes.

CONCLUSIONS

Strategies which combine different screening modalities may provide greater clinical and economic benefits. The collection of comprehensive screening data using a uniform format will enable comparative analysis across screening programmes in different countries, will improve our understanding of the disease and will allow identification of optimal screening modalities.

Is ulcerative colitis associated with survival among older persons with colorectal cancer in the US? A population-based case-control study

BACKGROUND

While ulcerative colitis (UC) is a risk factor for colorectal cancer, the association of UC with survival after colorectal cancer has not been studied in an older population.

AIMS

The objective of our study was to compare the survival of colorectal cancer between persons with and without UC.

METHODS

All cases of colorectal cancer (CRC) in persons 67 and older residing in a SEER catchment area and enrolled in the Medicare between 1993 and 1999 were assessed. We identified diagnosis of UC using ICD-9 codes on Medicare outpatient, office, and inpatient claims in the 2 years prior to the date of diagnosis. We used Cox proportional hazards model and Kaplan-Meier curves to compare survival between individuals with UC and CRC (UC-CRC) and sporadic CRC RESULTS: We identified 47,543 cases of colorectal cancer. Cases with UC-CRC tend to be diagnosed at earlier stages compared to sporadic CRC (42 vs. 37% local (TNM stage 1 and 2) and 11 vs. 17% distant spread (TNM stage 4), respectively; P value = 0.04). Controlling for age, gender, race and stage, diagnosis of UC did not affect the 3-year survival for CRC.

CONCLUSIONS

Colorectal cancers tend to be diagnosed at earlier stages among persons with UC, but there is no difference in 3-year survival rates for colorectal cancer among individuals with and without UC.

Reversion-inducing cysteine-rich protein with Kazal motif (RECK) expression: an independent prognostic marker of survival in colorectal cancer

Patient prognosis in colorectal cancer is determined as in most solid cancers by the extent of local invasion and the presence of lymph node and distant metastases. The invasive potential of a tumor depends on the ability to degrade extracellular matrix proteins, for example, by matrix metalloproteinases. An important inhibitor of matrix metalloproteinases is reversion-inducing cysteine-rich protein with Kazal motifs (RECK), a membrane-anchored glycoprotein. This study investigated the prognostic relevance of RECK expression in colorectal cancer in a cohort of 283 patients. Analysis of immunohistochemical tissue microarray data showed that RECK protein levels did not seem to correlate with clinicopathologic parameters (Spearman rank correlation coefficients between -0.14 and -0.18) and that decreased RECK expression was an independent prognostic factor of poor survival, with a mean survival of 70 months in RECK-negative (146 cases) versus 97 months in RECK-positive patients (137 cases) (log-rank test, P = .002).

Interactions between plasma levels of 25-hydroxyvitamin D, insulin-like growth factor (IGF)-1 and C-peptide with risk of colorectal cancer

Background

Vitamin D status and levels of insulin-like growth factor (IGF)-1 and C-peptide have been implicated in colorectal carcinogenesis. However, in contrast to vitamin D IGF-1 is not an easily modifiable risk factor.

Methods

Combining data from the Health Professionals Follow up Study (HPFS) and the Nurses' Health Study cohort (NHS) additive and multiplicative interactions were examined between plasma 25-hydroxyvitamin D (25(OH)D) and IGF-1, IGFBP-3 as well as C-peptide levels in 499 cases and 992 matched controls. For the various analytes, being high or low was based on being either above (or equal) or below the medians, respectively.

Results

Compared to participants with high 25(OH)D and low IGF-1/IGFBP-3 ratio (reference group), participants with a high IGF-1/IGFBP-3 ratio were at elevated risk of colorectal cancer when 25(OH)D was low (odds ratio (OR): 2.05 (95% CI: 1.43 to 2.92), but not when 25(OH)D was high (OR:1.20 (95% CI: 0.84 to 1.71, p(interaction): additive  = 0.06, multiplicative  = 0.25). Similarly, compared to participants with high 25(OH)D and low molar IGF-1/IGFBP-3 ratio and low C-peptide levels (reference group), participants with a combination of either high IGF-1/IGFBP-3 ratio or high C-peptide were at elevated risk for colorectal cancer when 25(OH)D was low (OR = 1.90, 95% CI: 1.22 to 2.94) but not when 25(OH)D was high (OR = 1.15, 95% CI: 0.74 to 1.77, p(interaction): additive = 0.004; multiplicative  = 0.04).

Conclusion

The results from this study suggest that improving vitamin D status may help lower risk of colorectal cancer associated with higher IGF-1/IGFBP-3 ratio or C-peptide levels.

Is inflammatory bowel disease an important risk factor among older persons with colorectal cancer in the United States? A population-based case-control study

BACKGROUND

While ulcerative colitis (UC) and Crohn's disease (CD) are thought to predispose to colorectal cancer (CRC), the association has not been well studied in an older population.

AIMS

The objective of our study was to evaluate the association of ulcerative colitis and Crohn's disease and colorectal cancer in a population-based, case-control study. We also wished to estimate the incidence rates of colorectal cancer among older individuals with UC/CD.

METHODS

All cases of colorectal cancer in persons 67 and older in the SEER catchment area and in the Medicare claims database were compared with cancer-free controls residing in the same geographic area. We used multivariable logistic regression models adjusted for demographic and other factors.

RESULTS

We identified 47,543 cases of CRC and 142,273 controls. We found a modest association between UC and CRC (OR 1.93; 95% CI 1.54-2.49; P-value<0.001) and a significant, albeit modest, association between CD and CRC (OR 1.45; 95% CI 1.08-1.91; P-value 0.01). We found the incidence of CRC to be 8.2 per 10,000 person-years (95% CI 6.5-10.1/10,000 person-years) among those with UC/CD, and 6.1 per 10,000 person-years (95% CI 4.6-7.8/10,000 person-years) among those without UC/CD, resulting in an incidence rate ratio of 1.34.

CONCLUSIONS

Among older persons ulcerative colitis and Crohn's disease are modest risk factors for CRC, and the incidence rate ratio for CRC is modest, suggesting that risk of CRC in patients with IBD may be lower than previously thought.

Meta-analysis: Serum vitamin D and colorectal adenoma risk

OBJECTIVE

To perform a systematic review and meta-analysis of human studies on the association between serum 25 hydroxyvitamin D (25(OH)D) and incident, sporadic colorectal adenoma (CRA) and CRA recurrence.

METHODS

Relevant studies among humans were identified by systematically searching Ovid Medline, EMBASE, and ISI Web of Knowledge databases and by cross-referencing. Due to the heterogeneity across studies in categorizing serum vitamin D levels, all results were recalculated for an increase of serum 25(OH)D by 20 ng/ml. Summary odds ratios (ORs) were calculated using meta-analysis methods.

RESULTS

Overall, 10 original studies were included. Specific results for incident CRA according to serum 25(OH)D were reported in 8 studies, and for CRA recurrence in 2 studies, respectively. In meta-analyses, summary ORs (95% confidence intervals) regarding incident and recurrent CRA, and both outcomes combined were 0.82 (0.69-0.97), 0.87 (0.56-1.35), and 0.84 (0.72-0.97), respectively, for an increase of 25(OH)D by 20 ng/ml. No publication bias was found.

CONCLUSION

Our results support suggestions that serum 25(OH)D levels are inversely associated with CRA risk.

Dietary patterns and the risk of colorectal adenomas: the Black Women's Health Study

BACKGROUND

Colorectal adenomas are benign lesions that may be precursors to colorectal cancer. No studies of African American women have investigated dietary patterns and the risk of developing colorectal adenomas. We examined data from the Black Women's Health Study to determine whether dietary patterns are associated with the risk of developing colorectal adenomas.

METHODS

This is a prospective cohort study of 59,000 participants followed biennially since 1995. During 155,414 person-years of follow-up from 1997 to 2007 among women who had had at least one screening colonoscopy, 620 incident cases of colorectal adenomas were identified. By using Cox regression models, we obtained incidence rate ratios (IRR) for colorectal adenoma in relation to quintiles of each of two dietary patterns, adjusting for other colorectal adenoma risk factors.

RESULTS

Two dietary patterns, Western and prudent, were utilized to assess the association between dietary intake and adenoma risk. The highest quintile of prudent diet, relative to the lowest quintile, was significantly associated with 34% lower colorectal adenoma risk overall (IRR = 0.66; 95% CI, 0.50-0.88; P(trend) < 0.01). Higher scores on the Western pattern were associated with a higher risk of developing colorectal adenoma (IRR = 1.42; 95% CI, 1.09-1.85 for the highest quintile relative to the lowest; P(trend) = 0.01).

CONCLUSION

Our findings suggest that African American women may be able to reduce their risk of developing colorectal adenomas by following a prudent dietary pattern and avoiding a more Western pattern.

IMPACT

A dietary modification could have a strong impact in colorectal adenoma prevention in African American women.

The first year follow-up after colorectal adenoma polypectomy is important: a multiple-center study in symptomatic hospital-based individuals in China

The recurrence of colorectal adenoma (CRA) is high. Although there are guidelines for colonoscopy surveillance after polypectomy in other countries, little is known about its recurrence rate and recurrence peak, especially in China. The aim of the present research is to investigate how long after polypectomy follow-up should take and to analyze risk factors of recurrence. 1208 patients who received polypectomies from five clinical research centers in four regions of China (Shanghai, Guangzhou, Nanjing and Beijing) were included. They were divided into 4 groups: group A (follow-up ≤ 1 year after polypectomy), group B (follow-up 2-3 years after polypectomy), group C (follow-up 4-5 years after polypectomy), and group D (follow-up > 5 years after polypectomy). The sex, age, adenoma location, size, number, and pathological characteristics were compared. On the whole, the recurrence rate was 59.46% in group A, 61.09% in group B, 78.07% in group C, and 87.12% in group D, which indicated an increased tendency with a prolonged follow-up duration. There was a significant difference between group A and C or D, and between group B and C or D (P<0.01), but there was no statistical difference between group A and B. Additionally, the recurrent patients in the first year had a recurrence rate of 97.33% in the first three years (59.46/61.09), which means that the peak of recurrence was almost entirely concentrated in the first year. The recurrence rate was higher in males and the elder. The risk factors included multiple numbers, villous feature, high-grade dysplasia of medium or smaller size and location in the distal colon. In conclusion, the peak of recurrence was almost totally concentrated in the first year; meanwhile, the first year follow-up is of critical importance in China. It may not be necessary to do the follow-up examination during the second and third years, but after three years, another colonoscopy should be undertaken.

The first year follow-up after colorectal adenoma polypectomy is important: a multiple-center study in symptomatic hospital-based individuals in China

The recurrence of colorectal adenoma (CRA) is high. Although there are guidelines for colonoscopy surveillance after polypectomy in other countries, little is known about its recurrence rate and recurrence peak, especially in China. The aim of the present research is to investigate how long after polypectomy follow-up should take and to analyze risk factors of recurrence. 1208 patients who received polypectomies from five clinical research centers in four regions of China (Shanghai, Guangzhou, Nanjing and Beijing) were included. They were divided into 4 groups: group A (follow-up ≤ 1 year after polypectomy), group B (follow-up 2-3 years after polypectomy), group C (follow-up 4-5 years after polypectomy), and group D (follow-up > 5 years after polypectomy). The sex, age, adenoma location, size, number, and pathological characteristics were compared. On the whole, the recurrence rate was 59.46% in group A, 61.09% in group B, 78.07% in group C, and 87.12% in group D, which indicated an increased tendency with a prolonged follow-up duration. There was a significant difference between group A and C or D, and between group B and C or D (P<0.01), but there was no statistical difference between group A and B. Additionally, the recurrent patients in the first year had a recurrence rate of 97.33% in the first three years (59.46/61.09), which means that the peak of recurrence was almost entirely concentrated in the first year. The recurrence rate was higher in males and the elder. The risk factors included multiple numbers, villous feature, high-grade dysplasia of medium or smaller size and location in the distal colon. In conclusion, the peak of recurrence was almost totally concentrated in the first year; meanwhile, the first year follow-up is of critical importance in China. It may not be necessary to do the follow-up examination during the second and third years, but after three years, another colonoscopy should be undertaken.

Bayesian calibration of a natural history model with application to a population model for colorectal cancer

BACKGROUND

Cancer natural history models are essential when evaluating screening/preventative interventions or changes to diagnostic pathways. Natural history models commonly use a state transition structure, but it is often not possible to observe the state transition probabilities required for parameterization.

AIM

. The work aimed to accurately represent the uncertainty in the parameters of a state transition model for the natural history of colorectal cancer by embedding the problem in the framework of Bayesian inference.

METHODS

The Metropolis-Hastings algorithm was used to estimate natural history parameters and screening test characteristics by generating multiple sets of parameters from the posterior distribution, which is the probability distribution that is compatible with the observed data. Observed data included colorectal cancer incidence categorized by age and stage, autopsy data on polyp prevalence, and cancer and polyp detection rates from the first round of screening with the fecal occult blood test in England. The approach was implemented using Visual Basic.

RESULTS

The results were subsequently examined for convergence using the package CODA in R 2.8.0. Outputs from fitting were samples from the joint posterior distribution of the natural history parameters given the epidemiological data. The parameter sets obtained are shown to have a good fit to all the observed data sets. These parameter sets are used when running probabilistic sensitivity analysis.

CONCLUSION

The advantages of this strategy are that it draws efficiently from a high-dimensional correlated parameter space. The algorithm is simple to code and runs overnight on a standard desktop PC. Using this method, the parameter sets are drawn according to their posterior probability given calibration data, and thus they correctly summarize the residual uncertainty in the parameter space.

Vascular endothelial growth factor 1498C/T, 936C/T polymorphisms associated with increased risk of colorectal adenoma: a Chinese case-control study

Single nucleotide polymorphisms in vascular endothelial growth factor gene VEGF, 1498C/T and 936 C/T are associated with colorectal cancer. We sought to determine whether such genetic variability in VEGF contributes to susceptibility of colorectal adenoma (CRA), a presumably precancerous state of colorectal cancer. In this research, two aforementioned polymorphisms were investigated for CRA susceptibility in a Chinese case-control study. The epidemiological risk factors were collected through questionnaire. The plasma VEGF levels were measured via enzyme-linked immunosorbent assay (ELISA). The Taqman-Probe assay was used to determine genotypes in 224 CRA patients and 200 CRA-free controls. The clinicopathological data of each sample were collected for further correlation analysis. According to data analysis males, cigarette smokers, patients who carry metabolic syndrome or familial antecedent of adenomas were significantly associated with CRA risk. Plasma VEGF levels of CRA patients were higher than those of controls (P = 0.003). This difference is independent of genotypes. The carriers with 936CT and CT+TT had higher risk of CRA in comparison with controls (CT vs. CC, OR 2.00, 95% CI 1.23-3.25, P = 0.006; CT+TT vs. CC, OR 2.04, 95% CI 1.28-3.26, P = 0.003). 936-T allele was associated with increased risk of CRA (OR 1.91, 95% CI 1.25-2.91, P = 0.003). Both CRA and control show no difference in the genotype of 1498C/T and the allele frequency of C-/T-. CRA patients with haplotype 1498T+936T presented significantly higher risk than those with wild-type 1498T+936C. Moreover, patients carrying 936CT+TT and 936-T allele demonstrated a tendency for villous adenoma. CRA patients have elevated plasma VEGF levels. The VEGF 936C/T polymorphism and 1498T+936T haplotype were found to be associated with increased CRA susceptibility.

Variation in detection of adenomas and polyps by colonoscopy and change over time with a performance improvement program

BACKGROUND & AIMS

There has been no prospective, community-based study to track changes in adenoma detection by individual physicians over time and to determine the effectiveness of targeted educational interventions.

METHODS

We prospectively collected information on 47,253 screening colonoscopies in average-risk individuals 50 years and older performed by a community-based practice in the Twin Cities of Minnesota. During a period of 3 years, 5 specific interventions were implemented; each was designed to improve adenoma detection rates. Controlling for patient-related and procedure-related factors, rates of adenoma detection and 3-year trends for individual physicians were plotted, and intraclass correlation coefficients were calculated. Generalized estimating equations were used to identify factors associated with detection of adenomas and polyps.

RESULTS

At least 1 polyp and 1 adenoma were found in 36% and 22% of examinations, respectively. Adenoma detection rates by endoscopists ranged from 10%-39%. There was no significant improvement during the study period despite planned, systematic interventions. Factors associated with adenoma detection included age of the patient (odds ratio [OR], 1.02; 95% confidence interval [CI], 1.02-1.02), male sex (OR, 1.53; 95% CI, 1.34-1.74), and adequate preparation quality (OR, 2.26; 95% CI, 1.64-3.12).

CONCLUSIONS

The detection of adenomas by individual physicians during a 3-year period varied and did not appear to change between individual endoscopists, despite planned, systematic interventions. This indicates that other targeted interventions might be required to improve adenoma detection rates among experienced, community gastroenterologists.

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.

Can calcium chemoprevention of adenoma recurrence substitute or serve as an adjunct for colonoscopic surveillance?

OBJECTIVES

The aim of this study was to examine the potential cost-effectiveness of calcium chemoprevention post-polypectomy as a substitute or adjunct for surveillance.

METHODS

We constructed a Markov model of post-polypectomy adenoma recurrence and colorectal cancer (CRC) development, calibrated to data from prospective chemoprevention trials of fiber, calcium, antioxidants, and aspirin. We modeled four scenarios for 50-year-old patients immediately after polypectomy: (i) natural history with no further intervention; (ii) elemental calcium 1,200 mg/day from age 50-80; (iii) surveillance colonoscopy from age 50-80 every 5 years, or 3 years for large adenoma; (iv) calcium + surveillance. Patients were followed up until age 100 or death.

RESULTS

Calcium was cost-effective compared to natural history ($49,900/life-year gained). However, surveillance was significantly more effective than calcium (18.729 versus 18.654 life-years/patient; 76 percent versus 14 percent reduction in CRC incidence) at an incremental cost of $15,900/life-year gained. Calcium + surveillance yielded a very small benefit (0.0003 incremental life-years/patient) compared with surveillance alone, at a substantial incremental cost of $3,090,000/life-year gained.

CONCLUSION

Post-polypectomy calcium chemoprevention is unlikely to be a reasonable substitute for surveillance. It may be cost-effective in patients unwilling or unable to undergo surveillance.

Meat Mutagens and Risk of Distal Colon Adenoma in a Cohort of U.S. Men

Cooking meats at high temperatures and for long duration produces heterocyclic amines and other mutagens. These meat-derived mutagenic compounds have been hypothesized to increase risk of colorectal neoplasia, but prospective data are unavailable. We examined the association between intakes of the heterocyclic amines 2-amino-3,8-dimethylimidazo[4,5,-f]quinoxaline (MeIQx), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,4,8-trimethylimidazo[4,5,-f]quinoxaline (DiMeIQx), and meat-derived mutagenicity (MDM) and risk of distal colon adenoma using a cooking method questionnaire administered in 1996 in the Health Professionals Follow-up Study cohort. Between 1996 and 2002, 581 distal colon adenoma cases were identified. Higher intake of MDM was marginally associated with increased risk of distal adenoma [fourth versus lowest quintile: odds ratio (OR), 1.39; 95% confidence interval (95% CI), 1.05-1.84; highest versus lowest quintile: OR, 1.29; 95% CI, 0.97-1.72; P(trend) = 0.08]. Adjusting for total red meat or processed meat intake did not explain those associations. Our data also suggested a positive association between higher MeIQx (highest versus lowest quintile: OR, 1.28; 95% CI, 0.95-1.71; P(trend) = 0.22) and risk of adenoma, but this association was attenuated after adjusting for processed meat intake. DiMeIQx and PhIP did not seem to be associated with risk of adenoma. In conclusion, higher consumption of mutagens from meats cooked at higher temperature and longer duration may be associated with higher risk of distal colon adenoma independent of overall meat intake. Because mutagens other than heterocyclic amines also contribute to MDM, our results suggest that mutagens other than heterocyclic amines in cooked meats may also play a role in increasing the risk of distal adenoma.

GSTM1, GSTT1, and GSTP1 polymorphisms and risk of advanced colorectal adenoma

Cigarette smoking is a risk factor for colon adenoma. The glutathione S-transferase enzymes are involved in the detoxification of carcinogenic compounds including those found in tobacco smoke, and thus, may be important modifiers of individual risk of developing this disease. We examined the prevalence of GSTM1 and GSTT1 gene deletions, and two GSTP1 polymorphisms in 772 cases with advanced colorectal adenomas (>1 cm, villous elements or high-grade dysplasia) of the distal colon (descending or sigmoid colon or rectum) and 777 sigmoidoscopy negative controls enrolled in the screening arm of the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial. Epidemiologic data on smoking was collected by self-administered questionnaire and DNA was extracted from whole blood or buffy coat. For GSTM1 and GSTT1, we used a newly developed TaqMan-based assay capable of discriminating heterozygous (+/-) individuals from those with two active alleles (+/+) and homozygous deletions (-/-). For GSTP1, the I105V and the A114V substitutions were identified using end point 5' nuclease assays (TaqMan). Adjusted odds ratios (OR) and 95% confidence intervals (95% CI) were determined using unconditional logistic regression, controlling for age, race, and gender. Advanced adenoma risk was increased in current/former smokers (OR, 1.4; 95% CI, 1.2-1.8). Risks were decreased in subjects with > or =1 inactive GSTM1 alleles (OR, 0.6; 95% CI, 0.4-0.9); and the association was independent of smoking status (P interaction = 0.59). Having > or =1 inactive GSTT1 allele was associated with increased risk among smokers (OR, 1.4; 95% CI, 1.1-1.9; P trend = 0.02) but not among never smokers (OR, 0.9; 95% CI, 0.6-1.3) and a significant interaction between smoking and genotype was observed (P interaction = 0.05). In summary, this is the first study to report associations between colorectal adenomas and GSTM1 wild-type and GSTT1 null allele among smokers. These findings only became apparent using a newly developed assay able to distinguish heterozygous from wild-type individuals. Our data provide evidence that phenotypic differences between these two groups exist.

Dietary patterns and risk of colon cancer and adenoma in a cohort of men (United States)

BACKGROUND

Examining the effects of dietary patterns on cancer risk may provide insights beyond the assessment of individual foods or nutrients.

DESIGN

In the health professionals follow-up cohort, associations between the 'prudent' and the 'western' dietary pattern and risk of colon cancer and adenomas were examined in 561 colon cancer cases and 1207 distal colon adenoma cases.

RESULTS

Higher prudent pattern scores were only weakly and non-significantly associated with decreased risk of colon cancer or distal colon adenoma (highest versus lowest quintile: colon cancer: multivariate adjusted relative risk (RR) = 0.84 (95% confidence interval (CI) = 0.64-1.10); p(trend) = 0.37; distal adenoma: multivariate odds ratio (OR) = 0.88 (95% CI = 0.73-1.08); p(trend) = 0.12). Our findings suggest a moderately increased risk of colon cancer and distal adenoma with higher western pattern scores (colon cancer: RR = 1.27 (95% CI = 0.96-1.69), p(trend) = 0.05; distal adenoma: OR = 1.28 (95% CI = 1.05-1.56), p(trend) = 0.01). Adding body mass index, which is positively related to western pattern and thus may be considered an intermediate endpoint between western pattern and colon cancer, attenuated associations somewhat but not substantially.

CONCLUSION

Our data do not provide evidence for an appreciable inverse association between higher prudent pattern scores and risk of colon cancer or distal colon adenomas, but do support a moderate positive association between higher western pattern scores and risk of colon cancer or distal colon adenomas.

Role of supplemental calcium in the recurrence of colorectal adenomas: a metaanalysis of randomized controlled trials

BACKGROUND

Colorectal adenomas are neoplastic growths that are important targets for chemoprevention. Dietary calcium is thought to play an important role in chemoprevention. However, the role of calcium supplementation for preventing recurrence of adenomas is controversial. We performed a systematic review and meta-analysis to study the role of calcium supplementation in preventing recurrence of adenomas.

METHODS

We searched electronic bibliographic databases (Cochrane Database of Systematic Reviews, Cochrane Controlled Trials Register, CINAHL, EMBASE, and MEDLINE) and contacted authors to identify potentially eligible studies.

RESULTS

We identified three trials including 1,485 subjects with previously removed adenomas who were randomized to calcium versus placebo supplementation. The study endpoint was recurrence of adenomas at the end of 3-4 yr in 1,279 patients who completed the trials. We found that the recurrence of adenomas was significantly lower in subjects randomized to calcium supplementation (RR: 0.80, CI: 0.68, 0.93; p-value = 0.004).

CONCLUSIONS

This systematic review and meta-analysis suggest that calcium supplementation prevents recurrent colorectal adenomas.

Colon cancer and genetic variation in folate metabolism: the clinical bottom line

So far, evidence for the relation between folate intake and colorectal cancer has been insufficient to lead to specific public health interventions. In principle, data on the relation between genetic variation in folate metabolism and colorectal neoplasia could be used to corroborate the data on the relation between folate intake or status and the disease, strengthening the evidence base for primary prevention. Issues in considering the relation between a health outcome and genetic variation in metabolism of nutrients or other food components include knowledge of gene function, linkage disequilibrium, population stratification, study size and quality, and gene-environment interaction. Overall homozygosity for MTHFR variant genotypes is associated with a reduced risk of colorectal cancer, the opposite of what might have been expected a priori. This has led investigators to place greater emphasis on the functions of folate and methylenetetrahydrofolate reductase in DNA synthesis. Folate and related nutrients may be important after adenoma formation. A challenge for the future is to characterize the effects of multiple genes influencing folate metabolism. Limited data for colorectal cancer suggest that the effect of a low folate diet overrides the effect of genotype, but two studies of adenomas suggested the opposite. Another potential role of information on genetic variation in folate metabolism is in the management of colorectal cancer but most studies have been small, have included selected patient groups, and have made limited adjustment for potentially important factors.

Review article: the prevention of colorectal cancer

Colorectal cancer is a leading cause of cancer mortality in the industrialized world. Survival remains poor because most cases are diagnosed at an advanced stage. It is a preventable disease as colorectal cancers usually develop slowly from an identifiable precursor lesion, the adenoma. The existing strategies for colorectal cancer prevention include dietary prevention, chemoprevention and endoscopic intervention. The exact relationship between diet, particularly fibre, and colorectal cancer remains unclear, with the most recent studies suggesting that dietary fibre may not decrease colorectal cancer risk as previously thought. Non-steroidal anti-inflammatory drugs have been shown to have a protective effect against colorectal cancer, but the adverse effect profile of the non COX-2 selective drugs, particularly the risk of gastrointestinal haemorrhage, precludes their widespread use. There is increasing evidence that colorectal cancer incidence and mortality can be decreased from endoscopic polypectomy and early detection of cancer. Faecal occult blood testing in the general population ('average-risk') has been shown in randomized trials to decrease mortality from colorectal cancer by 15--33%. Long-term results of randomized trials of the effectiveness of flexible sigmoidoscopy and colonoscopy screening in the general population are awaited. Targeting high risk individuals may also be an effective and efficient way to decrease the colorectal cancer burden. As many as 15--30% of colorectal cases may be due to hereditary factors. Individuals with one or two direct relatives affected are at moderate risk for colorectal cancer (empirical lifetime mortality from colorectal cancer approximately 10%) and approximately 2--3% of cases arise in individuals harbouring highly penetrant autosomal dominant mutations, which puts them at high-risk for colorectal cancer. Surveillance colonoscopy is offered to individuals at moderate and high risk for colorectal cancer.