Epidemiology of sociodemographic characteristics, lifestyle, medical history, and colon cancer: a case-control study among French Canadians in Montreal

Risk factors for early-onset colorectal cancer: systematic review and meta-analysis

Background

The incidence of early-onset colorectal cancer (EOCRC), which means colorectal cancer diagnosed in patients under 50 years, has been increasing around the world. However, the etiology remains unclear. This study aims to identify risk factors for EOCRC.

Methods

This systematic review was conducted in PubMed, Embase, Scopus, and Cochrane Library databases from inception to November 25, 2022. We examined risk factors for EOCRC, including demographic factors, chronic conditions, and lifestyle behaviors or environmental factors. Random-effects/fixed-effects meta-analysis was adopted to combine effect estimates from published data. Study quality was evaluated with the Newcastle-Ottawa Scale (NOS). Statistical analysis was performed Revman5.3. Studies not suitable for the meta-analysis were analyzed by a systematic review.

Results

A total of 36 studies were identified for this review, and 30 studies were included in the meta-analysis. Significant risk factors for EOCRC included male (OR=1.20; 95% CI, 1.08-1.33), Caucasian (OR=1.44; 95% CI, 1.15-1.80), a family history of CRC (OR=5.90; 95% CI, 3.67-9.48), inflammatory bowel disease (OR=4.43; 95% CI, 4.05-4.84), obesity (OR=1.52; 95%CI, 1.20-1.91), overweight (OR=1.18; 95% CI, 1.12-1.25), triglycerides (OR=1.12; 95% CI, 1, 08-1.18), hypertension (OR=1.16; 95% CI, 1.12-1.21), metabolic syndrome (OR=1.29; 95% CI, 1.15-1.45), smoking (OR=1.44; 95% CI, 1.10-1.88), alcohol consumption (OR=1.41; 95% CI, 1.22-1.62), a sedentary lifestyle (OR=1.24; 95% CI, 1.05-1.46), red meat (OR=1.10; 95% CI, 1.04-1.16), processed meat (OR=1.53; 95% CI, 1.13-2.06), Western dietary patterns (OR=1.43; 95% CI, 1.18-1.73) and sugar-sweetened beverages (OR=1.55; 95% CI, 1.23-1.95). However, no statistical differences were found for hyperlipidemia and hyperglycemia. Vitamin D may be a protective factor (OR=0.72; 95% CI, 0.56-0.92). There was considerable heterogeneity among studies (I²>60%).

Conclusions

The study provides an overview of the etiology and risk factors of EOCRC. Current evidence can provide baseline data for risk prediction models specific to EOCRC and risk-tailored screening strategies.

Risk Factors for Early-Onset Colorectal Cancer: A Systematic Review and Meta-analysis

BACKGROUND & AIMS

Despite the widespread increase in the incidence of early-onset colorectal cancer (EoCRC), the reasons for this increase remain unclear. The objective of this study was to determine risk factors for the development of EoCRC.

METHODS

We conducted a systematic literature review and meta-analysis of studies examining non-genetic risk factors for EoCRC, including demographic factors, comorbidities, and lifestyle factors. Random effects meta-analyses were conducted for risk factors that were examined in at least three studies. Heterogeneity was investigated using the Q-test and I² statistic.

RESULTS

From 3304 initial citations, 20 studies were included in this review. Significant risk factors for EoCRC included CRC history in a first-degree relative (RR 4.21, 95% CI 2.61-6.79), hyperlipidemia (RR 1.62, 95% CI 1.22-2.13), obesity (RR 1.54, 95% CI 1.01-2.35), and alcohol consumption (high vs. non-drinkers) (RR 1.71, 95% CI 1.62-1.80). While smoking was suggestive as a risk factor, the association was not statistically significant (RR 1.35, 95% CI 0.81-2.25). With the exception of alcohol consumption, there was considerable heterogeneity among studies (I² > 60%). Other potential risk factors included hypertension, metabolic syndrome, ulcerative colitis, chronic kidney disease, dietary factors, sedentary behaviour, and occupational exposure to organic dusts, but these were only examined in one or two studies.

CONCLUSIONS

The results of this study advance the understanding of the etiology of EoCRC. High-quality studies conducted on generalizable populations and that comprehensively examine risk factors for EoCRC are required to inform primary and secondary prevention strategies.

Adult-Attained Height and Colorectal Cancer Risk: A Cohort Study, Systematic Review, and Meta-Analysis

BACKGROUND

The influence of anthropometric characteristics on colorectal neoplasia biology is unclear. We conducted a systematic review and meta-analysis to determine if adult-attained height is independently associated with the risk of colorectal cancer or adenoma.

METHODS

We searched MEDLINE, EMBASE, the Cochrane Library, and Web of Science from inception to August 2020 for studies on the association between adult-attained height and colorectal cancer or adenoma. The original data from the Johns Hopkins (Baltimore, MD) Colon Biofilm study was also included. The overall HR/OR of colorectal cancer/adenoma with increased height was estimated using random-effects meta-analysis.

RESULTS

We included 47 observational studies involving 280,644 colorectal cancer and 14,139 colorectal adenoma cases. Thirty-three studies reported data for colorectal cancer incidence per 10-cm increase in height; 19 yielded an HR of 1.14 [95% confidence interval (CI), 1.11-1.17; P < 0.001), and 14 engendered an OR of 1.09 (95% CI, 1.05-1.13; P < 0.001). Twenty-six studies compared colorectal cancer incidence between individuals within the highest versus the lowest height percentile; 19 indicated an HR of 1.24 (95% CI, 1.19-1.30; P < 0.001), and seven resulting in an OR of 1.07 (95% CI, 0.92-1.25; P = 0.39). Four studies reported data for assessing colorectal adenoma incidence per 10-cm increase in height, showing an overall OR of 1.06 (95% CI, 1.00-1.12; P = 0.03).

CONCLUSIONS

Greater adult attained height is associated with an increased risk of colorectal cancer and adenoma.

IMPACT

Height should be considered as a risk factor for colorectal cancer screening.

Melanosis coli: A factor not associated with histological progression of colorectal polyps

OBJECTIVE

In this study we aimed to investigate the association of melanosis coli (MC) and the colorectal polyp detection rate (PDR).

METHODS

In all, 1104 MC patients and 62 181 non-MC participants were enrolled. And 2208 controls were matched by participants' age and gender, and quality of bowel preparation using the propensity score matching (PSM) method. Additionally, 490 polyps in MC and 980 in controls matched by age and gender, and size and location of polyps were analyzed. The association of PDR and pathological features of polyps with MC were also analyzed.

RESULTS

MC patients showed a higher PDR (44.3% vs 39.3%, P = 0.006) and detection rate of low-grade adenoma (45.4% vs 36.7%, P = 0.002) but fewer large polyps (≥10 mm) (18.8% vs 26.9%, P = 0.001), fewer polyps in the left colon (33.5% vs 40.0%, P = 0.018), and a lower detection rate of advanced adenoma/adenocarcinoma (17.4% vs 24.3%, P = 0.003) than the matched controls. On multivariate logistic regression analysis, MC was independently associated with an increased PDR (odds ratio 1.184, 95% confidence interval 1.045-1.343, P = 0.008). Analysis targeting polyps showed that there were significant differences in age, gender, location, and pathology (P < 0.001) between polyps with and without MC. However, after adjusting for participants' age and gender, size and location of polyps, there was no difference between the two groups in pathology (P = 0.635).

CONCLUSION

MC is independently associated with increased colorectal PDR, but not with histological progression of polyps.

Impact of Diarrhea after Drinking on Colorectal Tumor Risk: A Case Control Study

Background:

Recently, the number of colorectal cancer (CRC) cases in Japan has been increasing, and is strongly influenced by alcohol consumption. On the other hand, there are several reports suggesting a relationship between bowel movement (constipation and diarrhea) and CRC development. Moreover, it is generally known that diarrhea may occur after drinking. However, the mechanism by which drinking alcohol increases CRC is not fully clarified yet. We hypothesized that diarrhea after drinking may play an important role in colorectal carcinogenesis.

Methods:

We examined the presence of diarrhea after drinking and further evaluated the correlation of diarrhea after drinking with the incidence of colorectal tumors. To obtain the status of the feces, a self-recorded questionnaire survey was administered using the dietary-recording method. Blood samples were obtained to analyze the ALDH2 Glu504Lys and ADH1B His48Arg polymorphisms.

Results:

The participants were 417 patients who had undergone a total colonoscopy. The control was selected from 186 patients who underwent a medical checkup at the same hospital during the same time period. The odds ratio for all subjects was 2.1 (95% CI: 1.18 - 3.80), and that for heavy drinkers was 4.2 (1.48 - 11. 90).

Conclusions:

The results demonstrated that those who have diarrhea after drinking possess a high risk of developing colon tumors.

The Mexican consensus on chronic constipation

INTRODUCTION

Significant advances have been made in the knowledge and understanding of the epidemiology, pathophysiology, diagnosis, and treatment of chronic constipation, since the publication of the 2011 guidelines on chronic constipation diagnosis and treatment in Mexico from the Asociación Mexicana de Gastroenterología.

AIMS

To present a consensus review of the current state of knowledge about chronic constipation, providing updated information and integrating the new scientific evidence.

METHODS

Three general coordinators reviewed the literature published within the time frame of January 2011 and January 2017. From that information, 62 initial statements were formulated and then sent to 12 national experts for their revision. The statements were voted upon, using the Delphi system in 3 voting rounds (2 electronic and one face-to-face). The statements were classified through the GRADE system and those that reached agreement >75% were included in the consensus.

RESULTS AND CONCLUSIONS

The present consensus is made up of 42 final statements that provide updated knowledge, supplementing the information that had not been included in the previous guidelines. The strength of recommendation and quality (level) of evidence were established for each statement. The current definitions of chronic constipation, functional constipation, and opioid-induced constipation are given, and diagnostic strategies based on the available diagnostic methods are described. The consensus treatment recommendations were established from evidence on the roles of diet and exercise, fiber, laxatives, new drugs (such as prucalopride, lubiprostone, linaclotide, plecanatide), biofeedback therapy, and surgery.

A prospective study of the effect of bowel movement frequency, constipation, and laxative use on colorectal cancer risk

OBJECTIVES

Constipation and laxative use have been hypothesized to increase colorectal cancer (CRC) risk, but existing epidemiologic studies have been inconclusive. To address this issue, the authors prospectively examined the association between CRC incidence and constipation, non-fiber laxative use, and fiber laxative use among 75,214 participants of the VITamins And Lifestyle study.

METHODS

Information on bowel movement frequency as well as average 10-year non-fiber laxative use, fiber laxative use, and constipation was ascertained by means of a questionnaire. Patients were followed from the time of receipt of the baseline questionnaire (2000-2002) until 2008 for CRC incidence, over which time 558 incident CRC cases occurred. Cox proportional hazard models were used to estimate the multivariate-adjusted hazard ratios (HRs) and 95% confidence intervals (95% CI).

RESULTS

Compared with individuals who used non-fiber laxatives less than once per year, the HRs associated with low (1-4 times per year) and high (≥5 times per year) use were 1.49 (95% CI: 1.04-2.14) and 1.43 (95% CI: 0.82-2.28), respectively (Ptrend=0.05). HRs for CRC were statistically significantly decreased and lowest in individuals who reported using fiber laxatives often (4+ days per week for 4+ years) vs. those who reported no use (HR=0.44; 95% CI: 0.21-0.95), although the trend was not significant (Ptrend=0.19). No statistically significant associations between bowel movement frequency or constipation and CRC risk were observed.

CONCLUSIONS

Findings from this study suggest that risk for CRC increases with non-fiber laxative use and decreases with fiber laxative use. However, further observational and experimental studies are needed to clarify these relationships before drawing conclusions about the preferred treatment of constipation.

Risk of developing colorectal cancer and benign colorectal neoplasm in patients with chronic constipation

BACKGROUND

Chronic constipation (CC) is a highly prevalent health problem, potentially associated with increased risk of colorectal cancer (CRCancer).

AIM

To investigate the association between CC, its severity, and CRCancer by estimating the relative risk of developing CRCancer and benign colorectal neoplasm (BCN) among severity-stratified patients with and without CC.

METHODS

Chronic constipation patients from a large retrospective US claims database were matched 1:3 with CC-free controls by demographic characteristics. CRCancer and BCN prevalence were measured over 1 year. In pre-index CRCancer- and BCN-free patients, incidence rate ratios (IRRs) of new CRCancer and BCN were calculated. Multivariate regression models adjusted for comorbidities and family history. CC patients' disease severity was rated based on CC-related resource use. IRRs for new CRCancer and BCN were estimated for CC severity groups and controls.

RESULTS

Chronic constipation (N = 28,854) and CC-free (N = 86,562) patients had mean age 61.9 years; 66.7% were female. One-year CRCancer prevalence was 2.7% and 1.7%, and BCN prevalence was 24.8% and 11.9% for CC and CC-free patients, respectively. Adjusted IRRs between CC and CC-free patients were 1.59 [95% confidence interval (CI): 1.43-1.78] and 2.60 [95% CI: 1.51-2.70] for CRCancer and BCN, respectively. Patients with severe and very severe CC had significantly greater incidence of CRCancer and BCN. At ≥ 2 and ≥ 5 years of observation, CRCancer and BCN incidence remained consistently and significantly higher for CC patients.

CONCLUSIONS

Patients with chronic constipation are associated with significantly higher prevalence and incidence of colorectal cancer and benign colorectal neoplasm than matched chronic constipation-free patients. These risks increase with the severity of chronic constipation.

Diagnostic yield of colonoscopy for constipation as the sole indication

AIM

There is controversy over whether constipation as the only symptom should be an indication for routine diagnostic colonoscopy. The study was carried out to assess the prevalence of abnormal pathology on colonoscopy and to assess the risk factors for colonic neoplasia in patients with constipation but without 'high risk symptoms'.

METHOD

A cross-sectional, single-centre study was conducted on individuals who underwent colonoscopy for constipation as the sole indication between 2005 and 2008. Standardized endoscopic and pathology reports were reviewed. Univariable and multivariable analyses were performed.

RESULTS

A total of 786 patients (595 women, 75.7%; mean age, 57.4±13.5 years) underwent diagnostic colonoscopy for constipation. Forty-three (5.5%) had polyps, of whom 19 (2.4%) had hyperplastic polyps and 19 (2.4%) adenomas. No cancers were found. In patients with adenoma, the detection rate was 2.9% for patients below age 40 years and 1.7% for patients below age 50 years. Older age was associated with a polyp in both univariate and multivariate analysis. Gender, ethnicity and smoking were not associated with polyp or adenoma.

CONCLUSION

Colonoscopy for patients with constipation as the sole indication had a lower yield of neoplastic lesions than that for patients undergoing routine screening colonoscopy. Colonoscopy in constipation may only be warranted in patients who are over 50 years of age.

Bowel movement and constipation frequencies and the risk of colorectal cancer among men in the Netherlands Cohort Study on Diet and Cancer

The authors investigated the associations between bowel movement and constipation frequencies and colorectal cancer (CRC) endpoints among men in the Netherlands Cohort Study on Diet and Cancer (n = 58,279) and explored whether dietary fiber intake may modify associations. After 13.3 years (1986-1999), 1,207 CRC cases and 1,753 subcohort members were available for case-cohort analyses. Multivariate analyses showed a significantly increased hazard ratio for CRC overall and rectal cancer in men who reported having a bowel movement 1-2 times per day (second-highest category) as compared with once a day (CRC: hazard ratio (HR) = 1.29, 95% confidence interval (CI): 1.09, 1.53 (P(trend) < 0.001); rectal cancer: HR = 1.50, 95% CI: 1.15, 1.95 (P(trend) = 0.001)). Hazard ratios for CRC overall and rectal cancer were significantly decreased and lowest in men who reported suffering from constipation sometimes or more often versus never (CRC: HR = 0.76, 95% CI: 0.58, 0.98 (P(trend) = 0.02); rectal cancer: HR = 0.57, 95% CI: 0.35, 0.90 (P(trend) = 0.01)). No trends in the associations with proximal or distal colon cancer risk were observed. Interactions with dietary fiber intake were not significant. In this study, frequent bowel movements were associated with an increased risk of rectal cancer in men, and constipation was associated with a decreased risk.

History of asthma or eczema and cancer risk among men: a population-based case-control study in Montreal, Quebec, Canada

BACKGROUND

Epidemiologic evidence regarding the association between a history of allergic diseases and different cancer types has been inconsistent.

OBJECTIVE

To examine whether a history of asthma or eczema is associated with various cancers among Canadian men in a population based case-control study conducted in the 1980s.

METHODS

Questionnaire-based interviews were performed by a team of trained interviewers from August 1979 to March 1986. Information collected included self-reported history of a prior medical diagnosis of asthma and of eczema, medication use, and several covariates among 3,300 cancer cases and 512 population controls. Logistic regression models were used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the association between asthma or eczema and more than 20 cancer types combined, as well as for each of the 8 most common cancer types (stomach, colon, rectum, lung, prostate, bladder, skin, and lymph nodes).

RESULTS

Considering study participants who reported a prior medical diagnosis of the disease and medication use, a history of asthma was negatively associated with all cancer types combined (OR, 0.72; 95% CI, 0.5-1.1) and similarly for a history of eczema (OR, 0.66; 95% CI, 0.4-1.1). Although ORs between asthma and eczema and most individual types were below 1.0, only 2 ORs were significantly below 1.0: that between asthma and stomach cancer (OR, 0.27; 95% CI, 0.1-0.9) and that between eczema and lung cancer (OR, 0.34; 95% CI, 0.2-0.7).

CONCLUSION

Allergic conditions that result from a hyperreactive immune system might lead to a more efficient elimination of abnormal cells, thus lowering cancer risks.

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.

Association between cigarette smoking and colorectal cancer in the Women's Health Initiative

The evidence linking cigarette smoking to the risk of colorectal cancer is inconsistent. We investigated the associations between active and passive smoking and colorectal cancer among 146,877 Women's Health Initiative participants. Women reported detailed smoking histories at enrollment. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated for the association between smoking and overall and site-specific risk of colorectal cancer. Invasive colorectal cancer was diagnosed in 1242 women over an average of 7.8 years (range = 0.003-11.2 years) of follow-up. In adjusted analyses, statistically significant positive associations were observed between most measures of cigarette smoking and risk of invasive colorectal cancer. Site-specific analyses indicated that current smokers had a statistically significantly increased risk of rectal cancer (HR = 1.95, 95% CI = 1.10 to 3.47) but not colon cancer (HR = 1.03, 95% CI = 0.77 to 1.38), compared with never smokers. Passive smoke exposure was not associated with colorectal cancer in adjusted analyses. Thus, active exposure to cigarette smoking appears to be a risk factor for rectal cancer.

Diet and vitamin or mineral supplementation and risk of colon cancer by subsite in Canada

The study assesses the association of diet and vitamin or mineral supplementation with risk of proximal or distal colon cancer. Mailed questionnaires were completed by 1723 newly diagnosed, histologically confirmed colon cancer cases and 3097 population controls between 1994 and 1997 in seven Canadian provinces. Measurement included information on socio-economic status, physical activity, smoking habits, alcohol use, diet and vitamin or mineral supplementation. Odds ratios and 95% confidence intervals were derived through unconditional logistic regression. Linear regression was used to examine that dietary factors affect body mass index. The strongest positive associations between colon cancer risk and increasing total fat intake were observed for proximal colon cancer in men and for distal colon cancer in both men and women. Increased consumption of vegetables, fruit and whole-grain products did not reduce the risk of colon cancer. A modest reduction in distal colon cancer risk was noted in women who consumed yellow-orange vegetables. Significant positive associations were observed between proximal colon cancer risk in men and consumption of red meat and dairy products, and between distal colon cancer risk in women and total intake of meat and processed meat. We also saw strong associations between bacon intake and both subsites of colon cancer in women. When men were compared with women directly by subsite however, the results did not show a corresponding association. A significantly reduced risk of distal colon cancer was noted in women only with increasing intake of dairy products and of milk. Among men and women taking vitamin and mineral supplements for more than 5 years, significant inverse associations with colon cancer were most pronounced among women with distal colon cancer. These findings suggest that dietary risk factors for proximal colon cancer may differ from those for distal colon cancer.

Physical activity and colorectal cancer: the Fukuoka Colorectal Cancer Study

The number of cases of colorectal cancer in Japan has increased over the past few decades, and incidence rates are now among the highest in the world. The present investigation within the Fukuoka Colorectal Cancer Study, including 778 cases and 767 controls aged 20-74 years, examined the association between physical activity and colorectal cancer risk by subsite. Employment-associated and leisure time physical activity was assessed by a questionnaire and interview. Division of sites into the proximal and distal colon, as well as the rectum, revealed clear site-dependent protective effects, with adjustment for smoking, alcohol consumption, BMI and age. In males, greater job-related physical activity was associated with significant reduction of risk in the distal colon and rectum (P = 0.047 and 0.02, respectively), whereas total and moderate or hard non-job physical activity exerted effects limited to the rectum (P = 0.01 and 0.004, respectively). In females, job-related physical activity and moderate or hard non-job physical activity was also protective, but only in the distal colon. Separate assessment of the influence of BMI 10 years previous to the study showed increase in risk with obesity in males but not in females, limited to distal colon and rectum. The results of the present study indicate that physical activity associated with work and leisure-time exerts beneficial effects in Japanese, but not on the proximal colon.

An overview of the association between allergy and cancer

Numerous epidemiological studies have evaluated some aspect of the association between a history of allergy and cancer occurrence. In this article, an overview of the epidemiological evidence is presented with a discussion of a number of methodological issues important in this area of study. Literature searches were conducted using the MEDLINE database from 1966 through to August 2005 to identify articles that explored a personal history of allergic disorders as a risk factor for cancer. Although it is difficult to draw conclusions between allergy and cancer at many sites because of insufficient evidence or a lack of consistency both within and among studies completed to date, strong inverse associations have been reported for pancreatic cancer and glioma, whereas lung cancer was positively associated with asthma. Additional studies are needed to confirm these finding and to address the limitations of previous studies, including the validity and reliability of exposure measures and control for confounding. Further, large prospective studies using cancer incidence would be particularly useful, including studies using biological markers of allergic status to reduce potential misclassification and to confirm the results of previous studies based on self-report. There is also a need for further basic research to clarify a potential mechanism, should an association exist.

Measures of familial aggregation depend on definition of family history: meta-analysis for colorectal cancer

OBJECTIVE

Familial aggregation, a primary theme in genetic epidemiology, can be estimated from family studies based on an index person. The excess risk due to the presence of affected family members can be classified according to whether disease in the relatives is considered a risk factor for the index person (type I relative risk) or whether the disease status of the index person is considered a risk factor for the relatives (type II relative risk).

STUDY DESIGN AND SETTING

A meta-analysis of published colorectal cancer studies reporting a measure of familial association was performed and application of multilevel linear regression to model age-specific relative risks presented.

RESULTS

The pooled type I relative risk of colorectal cancer given any affected first-degree relative (based on 20 studies) was 2.26 (95% confidence interval CI = 1.86, 2.73) and decreased with the age of the consultand. The pooled type II estimate (based on seven studies) was 2.81 (95% CI = 2.05, 3.85).

CONCLUSION

Type I relative risks are useful in clinical counseling settings when a consultand wants to know his/her disease risk given his or her family history. Type II relative risks can be used to quantify the risk of disease to relatives of an affected individual and then identify subjects eligible for screening.

Relative and absolute risk of colorectal cancer for individuals with a family history: A meta-analysis

Accurate risk estimates for individuals with a family history of colorectal cancer are important for surveillance strategies. We systematically reviewed the literature on familial risks of colorectal cancer to determine relative risk estimates for categories of family history and translated these relative risk estimates into absolute risk estimates. A random-effects meta-analysis pooled the effect estimates from individual studies and actuarial life-table methods converted relative into absolute risks. Fifty-nine studies were identified including 47 that estimated the relative risk of developing colorectal cancer given at least one affected first-degree relative. The pooled risk estimate was 2.24 (95% CI 2.06 to 2.43) which rose to 3.97 (95% CI 2.60 to 6.06) with at least two affected relatives. A population lifetime risk of 1.8% for a 50-year old increased to 3.4% (95% CI 2.8 to 4.0) with at least one affected relative or 6.9% (95% CI 4.5 to 10.4) with two or more. Accurate absolute risk estimates show how cancer risks vary over time, particularly by pattern of family history and age of individual at-risk.

Low dose docosahexaenoic acid protects normal colonic epithelial cells from araC toxicity

Background

The nucleoside analogue arabinosylcytosine (araC) has been used for many years in the treatment of acute leukemia. Evidence in the literature suggests that araC may inhibit the growth of human colon carcinoma cell lines as well. Because araC action interferes with normal nucleoside metabolism, it is highly toxic to a number of normal cell types including bone marrow and intestinal mucosa cells. Here we investigate whether the omega-3 fatty acid docosahexaenoic acid (DHA) could selectively target araC toxicity toward colonic tumor cells while protecting the normal cells in vitro.

Results

Cultures of normal rat colonic epithelial cells (4D/WT) and those transformed by v-src (D/v-src) were supplemented with graded concentrations of DHA or arachidonic acid (AA) alone or in combination with araC. AraC was only 1.6 fold more toxic to D/v-src than 4D/WT in cultures without added fatty acids. Supplementing with as little as 3 μM of either AA or DHA increased araC toxicity by more than 30-fold in the tumorigenic cells. The toxic effect of araC on the normal cells was also increased by the fatty acid supplementation. IC₅₀ values were decreased 1.7 fold by DHA in the 4D/WT cells but a more than 7-fold decrease was observed during AA supplementation. As a result, the therapeutic index of araC (IC₅₀ normal/IC₅₀ tumor) was more than 3-fold higher in the DHA than the AA supplemented cells. The expression of protein kinase C isoform epsilon was decreased in AA alone supplemented D/v-src cultures but in combination with araC decreased only in DHA supplemented 4D/WT cells.

Conclusion

Low dose DHA supplementation may enhance araC chemotherapy in colon cancer while protecting normal tissues, possibly through control of PKC signalling pathways.

Bowel movement frequency and risk of colorectal cancer in a large cohort study of Japanese men and women

The relationship between bowel movement (BM) frequency and the risk of colorectal cancer was examined in a large cohort of 25 731 men and 37 198 women living in 24 communities in Japan. At enrolment, each participant completed a self-administrated questionnaire on BM frequency and laxative use. Incidence rate ratios (IRR) with 95% confidence intervals (CI) were estimated using Cox's proportional-hazard model. During the follow-up period (average length 7.6 years), 649 cases of colorectal cancer, including 429 cases of colon cancer, were identified. Among women, subjects who reported a BM every 2–3 days had the lowest risk of developing colorectal (IRR=0.71, 95% CI=0.52–0.97) and colon cancer (IRR=0.70, 95% CI=0.49–1.00), whereas those reporting a BM every 6 days or less had an increased risk of developing colorectal (IRR=2.47, 95% CI=1.01–6.01) and colon cancer (IRR=2.52, 95% CI=0.93–6.82) compared with those reporting ⩾1 BM per day. A similar, but nonsignificant, association between the frequency of BM and cancer risk was observed in men. There was no association between colorectal or colon cancer risk and laxative use. Regulating BM frequency might therefore have a role in the prevention of colorectal cancer.

Dietary carotenoids and risk of colon cancer: case-control study

Some epidemiological studies suggest that consumption of fruits and vegetables with a high carotenoid content may protect against colon cancer (CC). The evidence, however, is not completely consistent. Given the inconsistencies in findings in previous studies and continued interest in identifying modifiable risk factors for CC, a case-control study of French-Canadian in Montreal, Canada, was undertaken to examine the possible association between dietary carotenoids and CC risk and to investigate whether this association varies in relation to lifestyle factors such as smoking or diet, and particularly the high consumption of long-chain polyunsaturated fatty acids (LCPUFA). A total of 402 colorectal cases (200 males and 202 females) and 688 population-based controls matched for age, gender and place of residence were interviewed. Dietary intake was assessed through a validated food frequency questionnaire that collected information on over 200 food items and recipes. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated in unconditional logistic regression models. After adjustment for important variables such as total energy intake, no association was found between dietary intake of carotenoids and CC risk. For women with high intakes of LCPUFA, an inverse association was found between lutein + zeaxanthin and CC risk. ORs were 0.41; 95%CI (0.19-0.91), p=0.03 for eicosapentaenoic acid, and OR=0.36, 95%CI (0.19-0.78), p=0.01 for docosahexaenoic acid, when the upper quartiles of intake were compared to the lower. Among never-smokers, a significantly reduced risk of CC was associated with intake of beta-carotene [OR=0.44, 95%CI (0.21-0.92) and p=0.02], whereas an inverse association was found between lycopene intake and CC risk [OR=0.63, 95%CI (0.40-0.98) and p=0.05] among smokers. The results of our study suggest that a diet rich in both lutein + zeaxanthin and LCPUFAs may help prevent CC in French-Canadian females.

Population-based estimates of the prevalence of family history of cancer among women

OBJECTIVE

Family history of cancer is recognized as one of the most important risk factors in predicting personal cancer risk. Nevertheless, there are few published population-based estimates of family history prevalence by age categories.

METHODS

We used responses of female controls (n = 4,754) from the population-based Cancer and Steroid Hormone study (1980-1982) to estimate the frequency of family history of various cancers among female relatives. We determined the age- and race-specific prevalence of family history of breast, ovarian, endometrial, and other cancers in first-degree female relatives of women aged 20-54 years. To evaluate changes in reporting family history over time, we also analyzed responses of control women (n = 1,544) from the Women's Interview Study on Health (WISH) (1990-1992) to estimate the prevalence of family history of breast cancer.

RESULTS

The prevalence of a first-degree family history of breast, ovarian, endometrial, and cervical cancers was 6.4% (95% CI 5.7-7.1%), 1.1% (0.8-1.4%), 3.5% (3.0-4.0%), and 2.1% (1.7-2.5%), respectively. Among first-degree female relatives, the prevalence of family history of colon, lung, and thyroid cancers was 2.4% (2.1-2.9%), 1.5% (1.2-1.8%), and 0.5% (0.3-0.7%), respectively. The prevalence of family history of breast and colon cancers increased significantly with respondent's age. Similar results for family history of breast cancer were obtained from an analysis of responses from the WISH.

CONCLUSIONS

In addition to providing a point of reference for research and health policy, these results may be of interest to providers who care for female patients because of the usefulness of information about family history of cancer for assessing lifetime risk of cancer.

Height of young men

We analysed the height of young men in Belgium, using 613 257 records of medical examinations made prior to their conscription into the army (about 68% of the male population concerned). All analyses showed very significant associations. Height differed according to the region (-1.24cm in Wallonia, French-speaking and poorer) compared to Flanders (Dutch-speaking and richer), when "age-class" and year are taken into account. The smallest men lived in Hainaut (a deprived area), the tallest ones in Walloon Brabant (wealthy green suburbs of the capital). Height increased across time (+1.11cm, 1978-1990) and with "age-class" (+2.66cm, 18-26years), controlling for other factors. The increase in Brussels stops in 1983, probably due to other socio-demographic evolutions.

Constipation, laxative use, and colon cancer in a North Carolina population

OBJECTIVE

The aim of this study was to determine whether bowel movement frequency and laxative use and type were associated with risk of colon cancer in white and black men and women.

METHODS

We conducted a population-based, case-control study with equal representation by blacks. Eligible subjects between ages 40 and 80 yr residing in urban and rural communities in North Carolina were asked about bowel habits and laxatives during face-to-face interviews. There were 643 cases (349 white, 294 black) and 1048 controls (611 white, 437 black).

RESULTS

Constipation, defined as fewer than three reported bowel movements per wk, was associated with a greater than two-fold risk of colon cancer (OR 2.36; 95% CI = 1.41-3.93) adjusted for age, race, sex, and relevant confounders. The association was greater for women (OR 2.69; 95% CI = 1.46-4.94) than for men (OR 1.73; 95% CI = 0.61-4.88) and stronger in blacks than whites. Black women had the highest risk (OR 3.42; 95% CI = 1.60-7.34), which remained significant (OR 3.21; 95% CI = 1.46-7.04) even after excluding subjects with late stage (distant) disease. The OR for constipation was slightly higher for distal than for proximal colon cancers. There was no association with laxative use (OR 0.88; 95% CI = 0.69-1.11). Fiber commercial laxatives appeared to exert a protective effect in a small subgroup.

CONCLUSIONS

This study provides support for a positive association between constipation and increased risk for colon cancer. Women, especially black women with constipation, seem to be at the highest risk.

Induction of transitional cell hyperplasia in the urinary bladder and aberrant crypt foci in the colon of rats treated with individual and a mixture of drinking water disinfection by-products

Cancer of the urinary bladder and colon are significant human health concerns. Epidemiological studies have suggested a correlation between these cancers and the chronic consumption of chlorinated surface water containing disinfection by-products (DBPs). The present study was designed to determine if exposure to DBPs would cause preneoplastic or neoplastic lesions in the urinary bladder and colon of rats, and what effect a mixture of DBPs would have on these lesions. Male and female Eker rats were treated via drinking water with low and high concentrations of potassium bromate, 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), chloroform, or bromodichloromethane individually or in a mixture for 10 months. The urinary bladders and colons were examined for the presence of preneoplastic lesions. Cell proliferation in the urothelium was examined using immunohistochemical staining for bromodeoxyuridine. Aberrant crypt foci (ACF), as well as the number of individual crypts in each ACF, were identified and counted microscopically after staining with 0.2% methylene blue. Colon crypt cell proliferation and mitotic index were determined using immunohistochemical staining for proliferating cell nuclear antigen. Labeling indexes for the urinary bladder and colon were calculated based on the percentage of positively labeled cells. Treatment with the high dose of MX caused transitional epithelial hyperplasia and cell proliferation in the rat urinary bladder, and this effect was diminished in the high dose mixture animals. Treatment with 4 individual DBPs, as well as a mixture of them, caused the development of ACF, the putative preneoplastic lesion of colon cancer.

Insulin, insulin-like growth factors and colon cancer: a review of the evidence

Insulin and insulin-like growth factor (IGF) axes are major determinants of proliferation and apoptosis and thus may influence carcinogenesis. In various animal models, modulation of insulin and IGF-1 levels through various means, including direct infusion, energy excess or restriction, genetically induced obesity, dietary quality including fatty acid and sucrose content, inhibition of normal insulin secretion and pharmacologic inhibition of IGF-1, influences colonic carcinogenesis. Human evidence also associates high levels of insulin and IGF-1 with increased risk of colon cancer. Clinical conditions associated with high levels of insulin (noninsulin-dependent diabetes mellitus and hypertriglyceridemia) and IGF-1 (acromegaly) are related to increased risk of colon cancer, and increased circulating concentrations of insulin and IGF-1 are related to a higher risk of colonic neoplasia. Determinants and markers of hyperinsulinemia (physical inactivity, high body mass index, central adiposity) and high IGF-1 levels (tall stature) are also related to higher risk. Many studies indicate that dietary patterns that stimulate insulin resistance or secretion, including high consumption of sucrose, various sources of starch, a high glycemic index and high saturated fatty acid intake, are associated with a higher risk of colon cancer. Although additional environmental and genetic factors affect colon cancer, the incidence of this malignancy was invariably low before the technological advances that rendered sedentary lifestyles and obesity common, and increased availability of highly processed carbohydrates and saturated fatty acids. Efforts to counter these patterns are likely to have the most potential to reduce colon cancer incidence, as well as cardiovascular disease and diabetes mellitus.

APACC, a French prospective study on aspirin efficacy in reducing colorectal adenoma recurrence: design and baseline findings

Colorectal cancer is the second most frequent cause of death from cancer in western countries. Many lines of evidence suggest that non-steroidal anti-inflammatory drugs (NSAIDs) may offer chemoprevention against colorectal cancer. A multicentre, double-blind, randomized, controlled trial is underway to determine the efficacy of regular aspirin intake (160 or 300 mg/day) in reducing colorectal adenoma recurrence. We now report the baseline characteristics of subjects enrolled into the trial.

RESULTS

A total of 618 polyps were excised from 274 patients at the baseline colonoscopy. Men had on average (+/-SD) 2.5 +/- 1.8 polyps per subject and women had 1.7 +/- 1.2. Ninety-one (33.7%) had three or more adenomas and 183 (67.8%) had more than one adenoma measuring 10 mm or more in diameter. The mean (+/-SD) age of the subjects was 57.7 (+/- 9.4) years. Sixty-seven (24.9%) reported that they had previously had adenoma(s), 95 (35.2%) reported a family history of colorectal cancer and 41 (15.2%) a family history of colorectal adenomas.

PERSPECTIVE

All subjects will undergo a one-year clearance colonoscopy by February 2001. Clinical, molecular biological and dietary data will enable us to investigate other factors influencing the recurrence of adenomas in this group of high-risk subjects.

AGA technical review on constipation. American Gastroenterological Association

This literature review and the recommendations therein were prepared for the American Gastroenterological Association Clinical Practice and Practice Economics Committee. The paper was approved by the Committee on March 4, 2000, and by the AGA Governing Board on May 21, 2000.