Colorectal adenomas and energy intake, body size and physical activity: a case-control study of subjects participating in the Nottingham faecal occult blood screening programme

The impact of body weight on dysplasia of colonic adenomas: a case-control study

OBJECTIVE

Colorectal cancer (CRC) is common across countries in males and females. Most cases originate from adenomas harboring high grade dysplasia. Among risk factors, weight excess has been suggested to positively influence dysplasia progression. In this study, the relationship between dysplasia grade of adenomas and body mass index (BMI) categories was analyzed.

METHODS

This was a retrospective case-control study. A total of 4745 charts (59.8% females) from patients undergoing colonoscopy were collected. Data regarding age, sex, smoking habits, occupation, residence, personal history of CRC, personal history of polyps and BMI were retrieved. Adenomas with high-grade dysplasia were labeled as advanced.

RESULTS

They were 970 (20.4%) subjects with adenomas (cases: mean age 64.67 ± 11.35 years) and 3775 without (controls: mean age 56.43 ± 16.56 years). As expected, adenomas were significantly associated with overweight or obesity. After adjusting for all covariates the presence of advanced adenoma was significantly associated with age, male sex, smoking habits, personal history of CRC, overweight (OR = 1.298, IC 95% 1.092-1.697) and obesity (OR = 1.780, IC 95% 1.260-2.515).

CONCLUSIONS

Our findings support the protective effect a normal weight against advanced adenomas. Reduction of BMI value should be pursued in healthy programs.

Physically active individuals have a 23% lower risk of any colorectal neoplasia and a 27% lower risk of advanced colorectal neoplasia than their non-active counterparts: systematic review and meta-analysis of observational studies

BACKGROUND

Few studies have examined the associations between physical activity (PA), sedentary behaviour (SB) and risk of colorectal neoplasia (CN).

METHODS

We systematically searched Medline, Embase, PsyInfo, Cochrane and other sources from their inception to 30 September 2018 for cohort, case-control and cross-sectional studies that evaluated these associations in asymptomatic, average-risk subjects. Random-effect models were used to estimate relative risks (RRs) of any-type CN, advanced CN, and non-advanced CN, respectively, in individuals with the highest versus the lowest level of PA and SB. Dose-response analyses and subgroup analyses were conducted. The I² statistic was used to examine heterogeneity among studies.

RESULTS

We identified 32 observational studies, including 17 cross-sectional studies, 10 case-control studies and five longitudinal studies. PA (highest vs lowest) was inversely associated with risk for any-type CN (n=23 studies) and advanced CN (n=15 studies), with a RR of 0.77 (95% CI=0.71 to 0.83, I²=57.5%) and 0.73 (95% CI=0.63 to 0.82, I²=45.5%), respectively. There was no association between PA and non-advanced CN (n=5 studies). There was an as association between PA and any-type CN in both sexes, and also for the distal colon. We found no dose-response relationship between PA and any-type or advanced CN. Based on three studies identified, SB time (longest vs shortest) was associated with an increased risk of advanced CN (RR=1.24, 95% CI 1.04 to 1.49, I²=14.4%). No publication bias was detected by Begg's test.

CONCLUSION

We report a 23% lower relative risk of any type of CN and a 27% lower risk of advanced CN in people with the highest level of PA compared with those in the lowest.

A Multicenter Study of Colorectal Adenomas Rationale, Objectives, Methods and Characteristics of the Study Cohort

Background and Aims

The Multicenter Study of Colorectal Adenomas (SMAC) is a retrospective-prospective cohort study involving four Gastrointestinal Endoscopy Units in Italy. The main aim of the study is to evaluate the relationship between clinical and pathologic information at index colonoscopy and subsequent incidence of adenoma and colorectal carcinoma. We report the rationale, objectives and methods of the study, including patient characteristics at initial presentation.

Methods

All patients were consecutively identified from the endoscopy registries of the four Centres from January 1, 1985 to December 31, 1992. Inclusion criteria were: age 18-69 years, endoscopy performed with adequate toilette at least up to the rectosigmoid junction, and removal of all detectable polyps. Exclusion criteria were: familial adenomatous polyposis, inflammatory bowel diseases, adenocarcinoma in adenoma with infiltrated margins, previous invasive cancer at any site, colon resection and geographic inaccessibility.

Results

Out of 20,071 patients who underwent endoscopy at the four Centres, 11,959 fulfilled the eligibility criteria (5,892 males and 6,067 females, mean age = 51.1 ± 11.6 years). The main reasons for exclusion were age (n = 4,020) and previous or present colorectal cancer (n = 2,389). Symptoms were the most common reason for referral (72.3%), while post-polypectomy follow-up and positive fecal occult blood accounted for most of the remaining cases. A pancolonoscopy was performed in 3,088 patients (25.8%), while a left-sided endoscopy was performed in 7,887 (66%). A total number of 4,810 polyps were removed from 2,699 patients (2,994 adenomas, 1,580 hyperplastic polyps and 236 polyps lost after resection). A significant association (p < 0.001) between age and the endoscopic findings was observed. The subjects without polyps (n = 9,198) had the lowest age (mean = 49.9; 95%CL = 49.6 - 50.1) followed by the patients with hyperplastic polyps (n = 661; mean age = 52.3; 95%CL = 51.5-53.1), and the patients with adenomas (n = 1,732; mean age = 56.2; 95%CL = 55.8 - 56.6), and the patients with hyperplastic polyps and adenomas (n = 306; mean age = 57.2; 95%CL = 56.3 - 58.2). Polyps were diagnosed more frequently in males than in females (28.6% versus 17.0%; p < 0.0001).

Conclusion

This study provides some insights in the natural history of colorectal cancer and stresses the need to develop adequate strategies in the follow-up of subjects after either positive or negative colonoscopy.

Sedentary behavior is associated with colorectal adenoma recurrence in men

PURPOSE

The association between physical activity and colorectal adenoma is equivocal. This study was designed to assess the relationship between physical activity and colorectal adenoma recurrence.

METHODS

Pooled analyses from two randomized, controlled trials included 1,730 participants who completed the Arizona Activity Frequency Questionnaire at baseline, had a colorectal adenoma removed within 6 months of study registration, and had a follow-up colonoscopy during the trial. Logistic regression modeling was employed to estimate the effect of sedentary behavior, light-intensity physical activity, and moderate-vigorous physical activity on colorectal adenoma recurrence.

RESULTS

No statistically significant trends were found for any activity type and odds of colorectal adenoma recurrence in the pooled population. However, males with the highest levels of sedentary time experienced 47% higher odds of adenoma recurrence. Compared to the lowest quartile of sedentary time, the ORs (95% CIs) for the second, third, and fourth quartiles among men were 1.23 (0.88, 1.74), 1.41 (0.99, 2.01), and 1.47 (1.03, 2.11), respectively (p(trend) = 0.03). No similar association was observed for women.

CONCLUSIONS

This study suggests that sedentary behavior is associated with a higher risk of colorectal adenoma recurrence among men, providing evidence of detrimental effects of a sedentary lifestyle early in the carcinogenesis pathway.

Physical activity and risk of colon adenoma: a meta-analysis

BACKGROUND

Little evidence is available on the relation of physical activity with colon adenomas, a colon cancer precursor.

METHODS

We conducted a systematic literature review and meta-analysis of published studies (in English) through April 2010, examining physical activity or exercise and risk or prevalence of colon adenoma or polyp. Random effects models were used to estimate relative risks (RRs) and corresponding confidence intervals (CIs). A total of 20 studies were identified that examined the association and provided RRs and corresponding 95% CIs.

RESULTS

A significant inverse association between physical activity and colon adenomas was found with an overall RR of 0.84 (CI: 0.77-0.92). The association was similar in men (RR=0.81, CI: 0.67-0.98) and women (RR=0.87, CI: 0.74-1.02). The association appeared slightly stronger in large/advanced polyps (RR=0.70, CI: 0.56-0.88).

CONCLUSION

This study confirms previous reports of a significant inverse association of physical activity and colon adenoma, and suggests that physical activity can have an important role in colon cancer prevention.

Physical activity and gastrointestinal cancer prevention

Colorectal cancer is the third most common cancer globally and is a leading cause of cancer death. Gastric cancer contributes significantly to the global cancer burden, particularly in low- and middle-income countries. We reviewed the literature for studies on physical activity or exercise and colon, rectal, and gastric cancers as well as colonic adenomatous polyps. We identified 52 studies of colon cancer, 31 studies of rectal cancer, 23 studies of colon polyps, and 16 studies of gastric cancer. Of the 52 studies of physical activity and colon cancer, 37 found a statistically significant association between increased levels of physical activity and decreased colon cancer risk in at least one comparison. Accumulated evidence suggests that physical activity is associated with a 25% reduction in colon cancer risk. In line with previous reports, we found no indication that the association was more pronounced for occupational versus recreational physical activity, with both resulting in a risk reduction of about 22%. Evidence for other domains of physical activity (i.e., transportation or household physical activity) is limited. Evidence is emerging that individuals who are consistently active across the lifetime may obtain greater risk reductions than those who are only active in recent years. Despite consistent associations with colon cancer, evidence is more limited though suggestive that physical activity reduces risk of colon adenomas or adenoma recurrence. There is clear evidence that physical activity is not associated with rectal or gastric cancers.

Adiposity in relation to colorectal adenomas and hyperplastic polyps in women

OBJECTIVE

To examine whether BMI is independently related to colorectal adenomas and hyperplastic polyps.

METHODS

We conducted a cross-sectional study among 1,420 asymptomatic women aged 40-79 years who had undergone complete colonoscopy. Logistic regression was used to estimate the odds ratios (OR) and the corresponding 95% confidence intervals (CI) of adenomas and hyperplastic polyps.

RESULTS

We identified 953 women (67.1%) with no polyps, 292 (20.6%) with adenomas, and 175 (12.3%) with hyperplastic polyps. Among those with polyps, 75 women (5.3% of total women) were classified as having both adenomas and hyperplastic polyps. After adjusting for potential risk factors for colorectal cancer, BMI was related to increased risk of adenomas (OR comparing obese to normal weight women = 1.57; 95% CI = 1.07-2.29). Further, BMI was associated with enhanced risk of hyperplastic polyps (OR = 3.76; 95% CI = 2.35-6.01) and the combination of adenomas and hyperplastic polyps (OR = 2.84; 95% CI = 1.41-5.72).

CONCLUSIONS

Excess body mass is positively related to colorectal adenomas and hyperplastic polyps, particularly when both kinds of polyps are present in combination. Future studies should continue to delineate the possible differences in potential risk factors between colorectal adenomas and hyperplastic polyps. Such work should help further elucidate the possible causes of colorectal cancer.

Adiposity in relation to colorectal adenomas and hyperplastic polyps in women

OBJECTIVE

To examine whether BMI is independently related to colorectal adenomas and hyperplastic polyps.

METHODS

We conducted a cross-sectional study among 1,420 asymptomatic women aged 40-79 years who had undergone complete colonoscopy. Logistic regression was used to estimate the odds ratios (OR) and the corresponding 95% confidence intervals (CI) of adenomas and hyperplastic polyps.

RESULTS

We identified 953 women (67.1%) with no polyps, 292 (20.6%) with adenomas, and 175 (12.3%) with hyperplastic polyps. Among those with polyps, 75 women (5.3% of total women) were classified as having both adenomas and hyperplastic polyps. After adjusting for potential risk factors for colorectal cancer, BMI was related to increased risk of adenomas (OR comparing obese to normal weight women = 1.57; 95% CI = 1.07-2.29). Further, BMI was associated with enhanced risk of hyperplastic polyps (OR = 3.76; 95% CI = 2.35-6.01) and the combination of adenomas and hyperplastic polyps (OR = 2.84; 95% CI = 1.41-5.72).

CONCLUSIONS

Excess body mass is positively related to colorectal adenomas and hyperplastic polyps, particularly when both kinds of polyps are present in combination. Future studies should continue to delineate the possible differences in potential risk factors between colorectal adenomas and hyperplastic polyps. Such work should help further elucidate the possible causes of colorectal cancer.

Anthropometric risk factors for colorectal polyps in African-American women

OBJECTIVE

Colorectal adenomas are thought to be precursor lesions to colorectal cancer, a leading cause of cancer incidence and mortality in African-American women. Studies suggest that obesity is associated with risk of adenomas in white women, but little is known about the relation in African-American women. We prospectively examined the association between selected anthropometric factors and colorectal polyps in African-American women.

METHODS AND PROCEDURES

Data were obtained from the Black Women's Health Study (BWHS), a prospective cohort study of African-American women. From 1997 to 2003, we followed 33,403 women aged > or =30 years with no prior diagnosis of cancer or polyps. Cox regression was used to estimate incidence rate ratios (IRRs) and 95% confidence intervals (CIs) for risk of polyps, with adjustment for potential confounders.

RESULTS

After 211,797 person-years of follow-up, 1,189 cases of colorectal polyps were reported. The IRR comparing women with a current BMI > or =35 to <25 kg/m(2) was 1.35 (95% CI = 1.12-1.62), after adjustment for covariates including waist-to-hip ratio (WHR). Women who gained > or =30 kg since age 18 were 1.76 times as likely as those who gained <5 kg to report polyps (95% CI = 1.33-2.33). The IRR comparing the highest (>or =0.87) to lowest (<0.71) quintiles of WHR was 1.26 (95% CI = 1.04-1.54), after adjustment for covariates including BMI. BMI at age 18, adult height, and waist circumference (BMI-adjusted) were not materially associated with risk. Results were similar among women with a recent endoscopy.

DISCUSSION

Weight gain and obesity in adulthood may increase the risk of colorectal polyps in African-American women.

Physical activity before and after diagnosis of colorectal cancer: disease risk, clinical outcomes, response pathways and biomarkers

Physical inactivity may be responsible for 13-14% of colon cancer, an attributable risk greater than family history. Epidemiological evidence shows an association between occupational and recreational physical activity and colon cancer, but has not established whether physical activity is protective against low-risk or more advanced adenomas. The evidence is inconclusive as to whether physical activity protects against rectal cancer and is conflicting with respect to whether physical activity has equal effects on male and female risk of colorectal cancer. The effect of exercise 'interventions' on the risk of colorectal cancer is currently not known. Also, although inferences can be made from epidemiological studies, no optimal exercise regimen can be confidently prescribed for protection against colorectal cancer. There is little available evidence for the benefits of physical activity before diagnosis of colorectal cancer for disease-specific survival and prognosis, and the clinical effects of an exercise intervention after diagnosis have not been investigated. There is some evidence that improvements in cardiorespiratory fitness reduce adverse effects from cancer treatment when physical activity is undertaken following diagnosis of colorectal cancer. Markers/mechanisms by which physical activity may protect against colorectal cancer and/or improve disease prognosis include gastrointestinal transit-time, chronic inflammation, immune function, insulin levels, insulin-like growth factors, genetics and obesity. Research evidence is, however, limited as to whether these markers are beneficially affected by physical activity, either before or after diagnosis of colorectal cancer.

An association between obesity and the prevalence of colonic adenoma according to age and gender

BACKGROUND

Epidemiologic data on obesity as a risk factor for colonic adenoma with respect to gender have not yet been confirmed. Here, we aimed to compare the prevalence of colonic adenoma and of advanced polyps in age-stratified men and women at baseline, to examine the role of body mass index (BMI) on colonic adenoma risk according to age and gender, and to examine the influence of menopausal status.

METHODS

A total of 1744 asymptomatic patients (946 men, 798 women) who underwent colonoscopy for cancer screening at Ewha Mokdong Hospital, Seoul, Korea, between February and June 2005, were eligible. BMI was assessed, and histology, size, and location of the adenoma were examined for each patient. Women were interviewed for menopausal status and a history of hormone replacement therapy.

RESULTS

A significant increase in the prevalence of colonic adenoma and of advanced polyps was found to occur with age (P for trend < 0.01). The prevalences of adenoma and advanced polyps were higher in men in most age groups (P < 0.01), but no significant difference in prevalences was observed between genderes in patients 70 years of age or older. Moreover, a positive association between BMI and the prevalence of colonic adenoma and advanced polyps was shown in relatively young individuals of both gender (men in their thirties, P < 0.05; women in their forties, P < 0.05), and premenopausal women according to hormonal status (P = 0.01).

CONCLUSIONS

Our data suggest that obesity increases the risk of colonic adenoma in relatively young people and in premenopausal women subject to estrogen effects.

A Follow-up Study of Physical Activity and Incidence of Colorectal Polyps in African-American Women

BACKGROUND

Physical activity is associated with a reduced risk of colon cancer, but the effect of activity on colorectal adenomas, which are precursors to colon cancer, is uncertain. The influence of physical activity on colorectal adenomas among African-American women is of particular interest because African-American women have an increased risk of colon cancer relative to other U.S. women.

METHODS

We prospectively assessed the relation of physical activity to the incidence of colorectal polyps among African-American women. We followed 45,400 women in the Black Women's Health Study from 1997 to 2003. Data were obtained by biennial mailed questionnaires. During 287,029 person-years of follow-up, 1,390 women reported having been diagnosed with colorectal polyps. A review of medical records of 58 women who reported colorectal polyps indicated that 59% had adenomas and 41% had hyperplastic polyps. We converted hours per week of vigorous exercise and hours per week of walking to metabolic equivalent (MET)-hours. We estimated incidence rate ratios with Cox proportional hazard models, controlling for age, body mass index, smoking, family history of colorectal cancer, and education.

RESULTS

For total MET-hours/wk spent in walking and vigorous exercise, the incidence rate ratio decreased from 0.94 for <5 MET-hours/wk to 0.72 for >or=40 MET-hours/wk (P(trend) = 0.01). The inverse association was apparent among most subgroups examined, including women who may be at higher risk of colorectal adenomas because of being obese.

CONCLUSIONS

Increased physical activity is associated with a reduced incidence of colorectal polyps among African-American women.

Does physical activity modify the association between body mass index and colorectal adenomas?

Although both physical inactivity and obesity have been associated with an increased risk of colorectal adenomas, it is unclear whether physical activity modifies the relationship between obesity and colorectal adenomas or through what mechanism this might occur. The aim of this study is to evaluate whether physical activity modifies the relationship between body mass index (BMI) and colorectal adenomas and whether apoptosis is a plausible mechanism responsible for this effect modification. Study subjects were part of a large, cross-sectional study, the Diet and Health Study III. Consecutive patients underwent colonoscopy between August 1998 and March 2000. Apoptosis was measured by morphological evaluation of hematoxylin and eosin-stained sections obtained from rectal pinch biopsy samples. There were 226 patients with adenomas and 494 adenoma-free controls. When comparing overweight subjects with the referent group (high physical activity/normal BMI), the relative odds of having an adenoma decreased as physical activity increased: low (odds ratio, OR=1.6; 95% confidence interval, CI=0.7-3.4); moderate (OR=1.1; 95% CI=0.6-2.0); and high (OR=0.8; 95% CI=0.4-1.6). When comparing obese subjects with the referent group, relative odds of having an adenoma were increased regardless of physical activity level. Apoptosis was not associated with obesity or physical activity. Our results suggest that physical activity may modify the association between obesity and colorectal adenoma until a high level of obesity is achieved. Apoptosis does not appear to be associated with obesity or physical activity.

Dietary patterns and the risk of colorectal adenoma recurrence in a European intervention trial

The relations between individual foods and nutrients to colorectal tumours are conflicting. Few studies have taken into account the interdependence between individual components of diet and their possible interactions. The aim of the study was to examine the associations between dietary patterns and the risk of colorectal adenoma recurrence in the European fibre-calcium intervention trial. Among the 640 patients with confirmed adenomas at the index colonoscopy, 592 had an initial dietary assessment using a diet history questionnaire. The present analysis was restricted to 277 men and 165 women without history of adenoma prior to the index colonoscopy and who completed the study. The main end point was the 3-year recurrence of adenomas. Principal component analysis was used to identify dietary patterns from 50 food groups. Ninety-two patients presented new colorectal adenomas at the 3-year colonoscopy (65 men and 27 women). In men, three meaningful dietary patterns emerged from analysis, explaining 21.3% of variability. They were called 'Mediterranean', 'Sweets and snacks' and 'High fat and proteins' patterns. None of them were significantly related to the overall recurrence of colorectal adenomas either in univariate or multivariate analyses. Among women, the 'Mediterranean', the 'Western' and the 'Snacks' patterns explained 21.9% of variability. The 'Mediterranean' pattern characterized by a high consumption of olive oil, vegetables, fruit, fish and lean meat significantly reduced adenoma recurrence [second tertile: adjusted odds ratio (OR)=0.50, 95% confidence interval (CI)=0.18-1.42; third tertile: adjusted OR=0.30, 95% CI=0.09-0.98; P for linear trend=0.04]. The 'Western' and 'Snacks' patterns were not associated with recurrence among women. In conclusion, this study suggests that the Mediterranean dietary pattern may reduce the recurrence of colorectal adenomas, at least in women. These exploratory results need to be confirmed by larger studies.

Amount, Type, and Timing of Recreational Physical Activity in Relation to Colon and Rectal Cancer in Older Adults: the Cancer Prevention Study II Nutrition Cohort

Physical activity has consistently been associated with lower risk of colon cancer, but information is limited on the amount, type, and timing of activities. The relationship between physical activity and rectal cancer is unclear. We examined characteristics of recreational physical activity in relation to colon and rectal cancer in the Cancer Prevention Study II Nutrition Cohort of 70,403 men and 80,771 women (median age, 63 years); 940 colon and 390 rectal cancers were identified from enrollment in 1992 to 1993 through August 1999. The multivariate-adjusted rate ratios (95% confidence intervals) associated with any recreational physical activity compared with none were 0.87 (0.71-1.06) for colon cancer and 0.70 (0.53-0.93) for rectal cancer. Colon cancer risk decreased significantly with increasing total hours (P for trend without reference group = 0.007) and metabolic equivalent hours (P for trend = 0.006) per week of activities. No clear decrease in rectal cancer risk was seen with increasing hours per week of physical activity. Rate ratios (95% confidence intervals) were 0.72 (0.52-0.98) for &lt;2 hours, 0.68 (0.47-0.97) for 2 to 3 hours, 0.59 (0.41-0.83) for 4 to 6 hours, and 0.83 (0.59-1.16) for ≥7 hours per week of physical activity compared with none. Past exercise, as reported in 1982, was not associated with risk of either colon or rectal cancer. We conclude that increasing amounts of time spent at recreational physical activity are associated with substantially lower risk of colon cancer and that recreational physical activity is associated with lower risk of rectal cancer in older men and women.

Physical activity and colorectal cancer

Physical activity has been shown to reduce risk of colon cancer. Some studies have shown site-specific associations while others have not. The inverse association between physical activity and colon cancer is consistent although only 7 of 13 studies that have collected both colon and rectal cancer data in the same manner report reduced risk for rectal cancer; four of these studies detected statistically significant inverse associations. The frequency, duration and intensity of activity are important components of a public health message to reduce risk of colon cancer through performance of physical activity. However, difficulties in estimating the exact amount of activity needed and frequency and intensity of activity result in only crude estimates of dose needed for a protective effect. Much of the literature suggest that more intense activity is needed to reduce colon cancer risk and that somewhere between 3.5 and 4 hours of vigorous activity per week may be needed to optimise protection. Several biological mechanisms have been proposed to explain the association between physical activity and colon cancer; many of these mechanisms also support the observation that intense activities are most protective. Biological mechanisms include: physical activity increasing gut motility; enhancing the immune system; decreasing insulin and insulin-like growth factor levels; decreasing obesity; enhancing free radical scavenger systems; and influencing prostaglandin levels. The evidence taken together provides strong support for lack of physical activity being causally related to colon cancer. It has been estimated that 12-14% of colon cancer could be attributed to lack of frequent involvement in vigorous physical activity.

Use of colonoscopy as a primary screening test for colorectal cancer in average risk people

OBJECTIVE

The use of colonoscopy as a primary screening test for colorectal cancer (CRC) in average risk adults is a subject of controversy. Our primary objective was to build a predictive model based on a few simple variables that could be used as a guide for identifying average risk adults more suitable for examination with colonoscopy as a primary screening test.

METHODS

The prevalence of advanced adenomas was assessed by primary screening colonoscopy in 2210 consecutive adults at least 40 yr old, without known risk factors for CRC. Age, gender, and clinical and biochemical data were compared among people without adenomas, those with non-advanced adenomas, and those with any advanced neoplasm. A combined score to assess the risk of advanced adenomas was built with the variables selected by multiple logistic regression analysis.

RESULTS

Neoplastic lesions were found in 617 subjects (27.9%), including 259 with at least one neoplasm that was 10 mm or larger, villous, or with moderate-to-severe dysplasia, and 11 with invasive cancers. Advanced lesions were more frequent among men, older people, and those with a higher body mass index (BMI). These three variables were independent predictors of advanced adenomas in multivariate analysis. A score combining age, sex, and BMI was developed as a guide for identifying individuals more suitable for screening colonoscopy.

CONCLUSIONS

Age, gender, and BMI can be used to build a simple score to select those average risk adults who might be candidates for primary screening colonoscopy.

Exercise and gastrointestinal function and disease: an evidence-based review of risks and benefits

BACKGROUND & AIMS

Exercise is beneficial to health because it reduces the risk of cardiovascular and endocrine diseases, improves bone and muscle conditioning, and lessens anxiety and depression. However, the impact of exercise on the gastrointestinal system has been conflicting. This systematic literature review evaluates the effect of the different modes and intensity levels of exercise on gastrointestinal function and disease using an evidence-based approach. Although more applicable to trained athletes and individuals who are highly active and, as such, at risk to experience the side-effects of exercise, an effort was made to state the level or degree of exercise or the lack of such evidence.

RESULTS

Light and moderate exercise is well tolerated and can benefit patients with inflammatory bowel disease and liver disease. Physical activity can also improve gastric emptying and lower the relative risk of colon cancer in most populations. Severe, exhaustive exercise, however, inhibits gastric emptying, interferes with gastrointestinal absorption, and causes many gastrointestinal symptoms, most notably gastrointestinal bleeding.

CONCLUSIONS

This knowledge will enable physicians to prescribe physical exercise in health and disease and to better manage patients with exercise-related gastrointestinal disorders. Our understanding of exercise and its gastrointestinal manifestations as well as risks and benefits warrants further investigation.

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.

Obesity, weight gain and risk of colon adenomas in Japanese men

Obesity has been related to increased risk of colon cancer or adenomas, but the epidemiologic findings are not entirely consistent. We examined the relation of not only body mass index (BMI) but also waist-to-hip ratio (WHR) and weight gain to colon adenoma risk in men who received a preretirement health examination at the Japan Self Defense Forces (SDF) Fukuoka and Kumamoto Hospitals during the period from 1995 to 1996. In the series of 803 men at age 47-55 years, 189 cases of colon adenomas and 226 controls with normal total colonoscopy were identified. Weight at 10 years before was ascertained by referring to the recorded data. After allowance for hospital, rank in the SDF, smoking and alcohol use, weight gain over the past 10 years was significantly associated with increased risk of colon adenomas (odds ratio for > or = 6 kg versus < or =-2 kg = 2.2; 95% confidence interval 1.0-4.8). High BMI and high WHR were each associated with increased risk, but only WHR was related to the risk independently of weight gain. In particular, weight gain accompanied with a high WHR was associated with a significant increase in the risk. Men with high physical activity tended to have lower risk. Associations with obesity-related variables and physical activity were not materially differential as regards the location and size of adenoma. The findings indicate that weight gain in middle age leading to abdominal obesity increases the risk of colon adenomas, and consequently of colon cancer.

Energy balance and cancers

Energy balance results from the exact equilibrium between caloric intake and caloric expenditure. A caloric intake larger than caloric expenditure results in overweight, even obesity, but other determinants, like hormonal dysfunction and/or genetic traits may play a part in obesity syndrome. Obesity, and even overweight, have been recognized as risk factors for the development of cancers. Human epidemiological studies, which have tended to establish the nature of the relationship between energy balance and cancer, are summarized first, with the influence of the various factors which act both on obesity and on cancer risk. Among these factors are the macronutrients responsible for the caloric intake, and some lifestyle factors (physical activity, drinking habits and tobacco use). Second, the animal studies help to distinguish between different relevant factors, and to understand some of the underlying mechanisms. However, the insulin-resistance syndrome, which appears to underlie the relationship between obesity and hormone-dependent cancers, and possibly colon cancer, is only relevant to human physiology because hormonal alterations are part of it. Prevention of hyperinsulinemia, insulin resistance and the accompanying visceral obesity appears to be a major public health task for the prevention of cancers.

A sigmoidoscopy-based case-control study of polyps: macronutrients, fiber and meat consumption

We conducted a large, sigmoidoscopy-based case-control study to examine the relation of intake of macronutrients, meat, and fiber to occurrence of adenomas of the large bowel. Cases were subjects diagnosed for the first time with one or more histologically confirmed adenomas. Controls had no polyps of any type at sigmoidoscopy, had no history of polyps, and were individually matched to cases by gender, age, date of sigmoidoscopy, and Kaiser Center. The response rate was 84% for cases and 82% for controls. Complete dietary data for 488 matched pairs were available. All odds ratios are from matched analyses adjusted for energy. We observed positive associations with risk of adenomas for calories, animal fat, saturated fat, red meat, and the ratio of red meat to poultry and fish. Protective effects were observed for vegetable protein, carbohydrates, and dietary fiber. The fiber effects diminished after adjusting for fruits and vegetables. Results after mutually adjusting for the effects of saturated fat, fiber and the ratio of red meat to chicken and fish suggest that each of these variables has an effect on risk of adenomas that is independent of the other 2 exposures.

Recent and past physical activity and prevalence of colorectal adenomas

Epidemiological evidence has generally supported a protective association of physical activity with large-bowel adenomas, but whether the protective effects are restricted to recent or past activity is uncertain. We determined whether recent and past recreational or total daily activity was associated with prevalence of colorectal adenomas among male and female members of a prepaid health plan in Los Angeles who underwent sigmoidoscopy (n = 488 matched pairs). Participants, aged 50-74 years, completed a 126-item semiquantitative food frequency questionnaire and were also interviewed regarding non-dietary risk factors in 1991-93. In the univariate analysis, all measures of recent recreational physical activity were associated with reduced prevalence of polyps. After adjustment for body mass index, smoking status, daily servings of fruit and vegetables, use of non-steroidal anti-inflammatory agents and intakes of calories, saturated fat and alcohol, the associations were weakened. For subjects engaging in high-intensity activities compared with subjects not engaging in vigorous activities, the multivariate odds ratio (OR) for recent recreational activity was 0.7 [95% confidence interval (CI) 0.4-1.1, trend P = 0.08]. Past recreational activity and past or recent total daily activity were not associated with prevalence of adenomas. These results support a modest association of recent recreational physical activity with prevalence of colorectal adenomas.

Leisure and occupational physical activity and risk of colorectal adenomatous polyps

Multiple studies have shown a protective effect for physical activity on the incidence of colorectal cancer, but few have addressed its association with incident adenomas and none have investigated its association with metachronous adenomas. We interviewed 2,001 patients undergoing colonoscopy in 3 New York City practices between 1986-1988. Of these, 298 had a first diagnosis of adenomas, 506 had normal colonoscopies, 197 had metachronous adenomas and 345 had normal colonoscopies with a past history of adenomas. Subjects were queried regarding use of moderate amounts of recreational exercise (swimming, jogging, biking, racket sports and other sports) on a regular basis, and were also asked to estimate their level of physical activity. Occupational physical activity was assessed through a blinded coding of occupational titles. After adjusting for age, years of education, body mass index, total caloric intake, dietary fiber intake, dietary fat intake and years of cigarette smoking, protective effects of borderline significance were observed among males for leisure physical activity for metachronous and incident cases. Occupational physical activity was found to be significantly protective in male incident cases. Men with increased levels of either occupational or leisure activity showed a reduction for incident and metachronous cases. No effects were observed for females. Thus, in this study, both leisure and occupational physical activity were associated with a reduced risk of incident and metachronous adenomas among men but not women.

Socioeconomic circumstances and the risk of bowel cancer in Northern Ireland

OBJECTIVE

To describe the variation in the incidence of colorectal cancer across Northern Ireland and relate it to factors associated with community deprivation.

DESIGN

This was a cross sectional descriptive study.

SETTING

Incidence data were obtained from a population based register for the period 1990-91. Small areas were characterised by their "affluence", or lack of it, by deriving a Townsend deprivation score for each electoral ward, using information from the 1991 census. PARTICIPANTS, MAIN OUTCOME MEASURES, AND STATISTICAL METHODS: The age standardised incidence was calculated for all colorectal cancer cases diagnosed histologically in 1990-91. Electoral wards were grouped into quintiles of the population after ranking of their Townsend scores and the association with incidence was studied using Poisson regression.

RESULTS

The age standardised colorectal cancer incidence ranged from 22.5 (for quintile 1) to 29.9/100,000 (quintile 5) for men but the trend for women was less regular and rates were 18.4, 23.8, 27.3, 26.5, and 23.9/100,000 for quintiles 1-5 respectively (that is, from the most "affluent" to the most "deprived" fifths of the population). After adjusting for age and sex in Poisson regression, there was a significant association between the total colorectal cancer incidence and levels of community deprivation. The rate ratio for the most deprived quintile of the population (compared with the least) was 1.28 (95% CI 1.06,1.53). The effect was stronger for rectal cancer than for colonic cancer. There was no association between community deprivation and the cancer stage at diagnosis.

CONCLUSIONS

In this population, the colorectal cancer incidence is associated with the level of material deprivation. The disease stages at the time of diagnosis in patients from more deprived areas seem to be comparable with those of patients from affluent areas. As others have shown, associations such as these are not explicable entirely on the basis of the distribution of known risk factors. Further research is needed to determine plausible mechanisms for the association.

Nutrition and colorectal cancer

Epidemiologic evidence on the relation between nutrition and colorectal cancer is reviewed. Colon cancer varies approximately 20-fold internationally. Although there is clear evidence of genetic predisposition to colon cancer, much of this variation appears to be related to differences in dietary habits. At present, the data suggest that vegetables are associated with lower risk, and that fiber alone does not account for this association. Further, meat consumption is associated with increased risk but this, too, is not explained solely by its fat content. Several microconstituents of the diet may be associated with reduced risk--including folate and calcium--but phytochemicals of other sorts may be relevant. Mutagenic compounds, particularly heterocyclic amines, produced when protein is cooked, plausibly explain the meat association. The most consistent inverse association is with physical activity. Alcohol is associated, though inconsistently, with increased risk. Rectal cancer is less well studied but, at present, there are few data to suggest that the dietary risk factors are markedly different. Physical activity does not appear to be associated with a lower risk. Colorectal adenomatous polyps also appear to share the spectrum of risk factors seen with colon cancer, although, for adenomas, tobacco smoking is also a clear and consistent risk factor. There are a variety of links between the dietary epidemiology and physiology of colorectal neoplasia and the relevant pathologic and molecular changes. Other causal connections remain to be explicated.

The relation of smoking, alcohol use and obesity to risk of sigmoid colon and rectal adenomas

We conducted a case-control study, using 429 cases with histologically confirmed sigmoid adenoma, 75 cases with rectal adenoma, and 3101 controls showing normal colonoscopy at least up to 60 cm from the anus. The subjects were male Self-Defense Forces personnel aged 48-56 who received a retirement health examination including a routine sigmoid- or colonoscopy. Lifestyle characteristics were ascertained by a self-administered questionnaire. Smoking in the recent past (< or = 10 years preceding the colonoscopy) and smoking in the remote past (> 10 years before the colonoscopy) were both significantly associated with risk of sigmoid adenoma but not with rectal adenoma as a whole. After reciprocal adjustment for smoking in the two periods, only smoking in the recent past was associated with both sigmoid colon and rectal adenomas. Odds ratios (OR) of sigmoid adenoma (and 95% confidence interval) for the categories of 0, 1-150, 151-250 and > or = 251 cigarette-years were 1.0 (reference), 1.9 (1.3-2.8), 2.1 (1.4-3.0) and 3.0 (1.9-4.7), respectively (P for trend < 0.01), and those for rectal adenoma were 1.0 (reference), 1.2 (0.4 3.2), 3.5 (1.4-8.5) and 2.0 (0.6 6.7), respectively (P for trend = 0.03). Alcohol use was significantly positively associated with sigmoid adenoma, and insignificantly associated with rectal adenoma. Body mass index was significantly positively associated with sigmoid adenoma, especially large ones. No such association was found for rectal adenoma. These findings suggest that smoking, especially in the recent past, and alcohol use are common risk factors for sigmoid colon and rectal adenomas while obesity may be exclusively related to the growth of sigmoid adenoma.

Obesity and cancer risk: a Danish record-linkage study

A cohort of 43,965 obese persons was accrued on the basis of discharge registrations from Danish hospitals, and incidence of cancer in the cohort was compared to that in the Danish population as a whole using indirect standardisation for age and period. Increased incidence was observed for cancer of the uterine corpus independently of age [114 cases, relative risk (RR) = 2.0, confidence interval 1.6-2.4], and for breast cancer in women above the age of 70 (133 cases, RR = 1.2). These findings are consistent with previous studies. In younger women, breast cancer occurred less frequently and ovarian cancer occurred more frequently than expected. Increased incidence was observed for cancers of the oesophagus (26 cases, RR = 1.9) and the liver (58 cases, RR = 1.9), probably reflecting an increased prevalence of excessive alcohol consumption in the cohort. Increased incidence was furthermore observed for cancers of the pancreas (101 cases, RR = 1.7), the prostate (96 cases, RR = 1.3) and the colon (195 cases, RR = 1.2), which may indicate the existence of risk factors which are common to obesity and to these cancers, for example, dietary habits. Kidney cancer was increased in women only. Overall, the incidence of cancer was increased by 16% in the cohort. The results were essentially unchanged by restriction to the subcohort of 8207 persons in whom obesity was the primary discharge diagnosis, and were also similar in the first year of follow-up after hospital discharge. Selection bias is, therefore, not likely to have influenced the results.