A prospective study of body mass, height, and smoking on the risk of colorectal cancer in women

Association of High Body Mass Index in Early Life With the Development of Colorectal Cancer

SIGNIFICANCE

This study on the relationship between early life high BMI and the development of CRC reveals the role of high BMI during childhood and adolescence in the occurrence and progression of CRC. It suggests the importance of restoring normal weight or reducing weight in individuals with high BMI early in life for the prevention of colorectal cancer.

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.

Affordability and features of home scales for self-weighing

Self-weighing is an evidence-based weight management strategy, which requires patients to have a home scale. For clinicians to effectively counsel patients on self-weighing, they should be aware of the costs and features available in typical home scales. Our objective was to describe the cost and features of the top bathroom scales available online. We performed content analysis of top 100 scales listed on a popular online retailer. Two coders independently extracted price and scale features (i.e., digital connectivity, body mass index [BMI] calculation, maximum weight accommodated). We used t-tests and ANOVA, as appropriate, to examine the relationships between price and features. Among the 97 scales included, mean scale price was $28.99 (SD $21.06; range $7.20-$139.95). Of the advanced features, 20.6% of scales had digital connectivity and 28.9% calculated BMI. Scales with advanced features cost significantly more than scales without (digital connectivity: $49.18 vs. $23.74, P < 0.001; BMI calculation: $42.92 vs. $23.33, P < 0.001). Most scales (76.2%) had a maximum weight of 351-400 lbs, and only 17.5% could accommodate >400 lbs. Price was higher for scales with a higher maximum weight (P = 0.002). No scale with maximum weight > 500 lbs had advanced features. Scales that have digital connectivity for telemedicine or can accommodate higher weights are less commonly available online and their costs may be prohibitive for some patients who need these features. Future research might consider testing whether insurance coverage for scales improves scale access and patient weight management outcomes.

Cigarette smoking, alcohol consumption, and risk of colorectal cancer in South Korea: A case-control study

The current case-control study comprehensively evaluated the status, quantity, and duration of smoking and alcohol drinking for both men and women, considering the subsites of colorectal cancer. A total of 925 colorectal cancer cases and 2775 controls were included in the analysis. Odds ratios (OR) and 95% confidence intervals (CI) were computed by logistic regression models adjusting for potential confounders. In men, the risk of colorectal cancer significantly increased for heavy smokers who smoked ≥40 pack-years (OR 1.74, 95% CI 1.22-2.50), ≥40 years (OR 1.50, 95% CI 1.05-2.16), or ≥40 cigarettes/day (OR 1.92, 95% CI 1.04-3.54). Men showed a significant increase in risk, especially for rectal cancer with an increasing amount or duration of smoking. In women, distal colon cancer risk increased in smokers who smoked ≥20 years (OR 3.21, 95% CI 1.27-8.14) or ≥20 cigarettes/day (OR 4.75, 95% CI 1.09-20.57). Additionally, female smokers who smoked ≥20 cigarettes/day had an increased risk of rectal cancer (OR 6.46, 95% CI 1.64-25.46). Regarding the association of cigarettes smoked per day and the risk of rectal cancer, there was no significant difference between men and women (gender interaction p value = 0.14). Compared with never-drinkers, those who consumed alcohol at ≥40 g/day in men and ≥20 g/day in women had an OR of 2.39 (95% CI 1.68-3.41) and 3.52 (95% CI 1.56-7.96), respectively. The effect of daily alcohol consumption (g of ethanol/day) on cancer risk was not significantly different among subsites. Association of alcohol consumption quantity (g of ethanol/day) and the risk of proximal and distal colon cancer were stronger in women than in men (gender interaction p value < 0.01). There was no significant interaction in the multiplicative level when alcohol consumption and cigarette smoking were combined. The duration and amount of smoking as well as the amount of alcohol consumption were associated with an elevated risk of colorectal cancer in both men and women.

Height and risk of colorectal cancer: a meta-analysis

Several epidemiological studies have investigated the relationship between height and risk of colorectal cancer (CRC), but the results were inconsistent. Thus, a meta-analysis of observational studies was carried out to clarify this association. A literature search was performed in PubMed and Web of Science databases for all relevant studies up to 25 May 2016. The random-effects model was used to calculate the pooled relative risks (RRs) and restricted cubic spline model was adopted for the dose-response analysis. A total of 31 studies involving 13 077 848 participants with 93 818 cases were included. The pooled RR (95% confidence interval) of CRC for the highest versus the lowest category of height was 1.25 (1.18-1.32); the pooled RR was 1.32 (1.22-1.43) for colon cancer and 1.12 (1.05-1.19) for rectal cancer for the highest versus the lowest category of height. A nonlinear relationship was found between height and the risk of CRC in the dose-response analysis (Pnonlinearity=0.0024). This meta-analysis indicates that height is associated with an increased risk of CRC.

Controversy on the correlation of red and processed meat consumption with colorectal cancer risk: an Asian perspective

This study aimed to investigate the relationship between meat intake and colorectal cancer risk from an Asian, particularly Korean, perspective. A report by the International Agency for Research on Cancer (IARC) published in 2015 concluded that intake of processed and red meat increases the risk of developing colorectal cancer. We conducted an in-depth analysis of prospective, retrospective, case-control and cohort studies, systematic review articles, and IARC monograph reports, which revealed that the IARC/WHO report weighted the results of studies based in Western countries more and that the correlation between intake of processed meat products and colorectal cancer incidence in Asians is not clearly supported. Among 73 epidemiological studies, approximately 76% were conducted in Western countries, whereas only 15% of studies were conducted in Asia. Furthermore, most studies conducted in Asia showed that processed meat consumption is not related to the onset of cancer. Moreover, there have been no reports showing significant correlation between various factors that directly or indirectly affect colorectal cancer incidence, including processed meat products types, raw meat types, or cooking methods. Further epidemiological studies taking each country's food culture into consideration are required to reliably elucidate the effects of processed meat product intake, especially on cancer incidence.

Childhood body mass index and height in relation to site-specific risks of colorectal cancers in adult life

As colorectal cancers have a long latency period, their origins may lie early in life. Therefore childhood body mass index (BMI; kg/m²) and height may be associated with adult colorectal cancer. Using a cohort design, 257,623 children from The Copenhagen School Health Records Register born from 1930 to 1972 with measured heights and weights at ages 7 to 13 years were followed for adult colon and rectal adenocarcinomas by linkage to the Danish Cancer Registry. Hazard ratios (HRs) with 95% confidence intervals (CI) were estimated by Cox proportional hazard regressions. During follow-up, 2676 colon and 1681 rectal adenocarcinomas were diagnosed. No sex differences were observed in the associations between child BMI or height and adult colon or rectal cancers. Childhood BMI and height were positively associated with colon cancer; at age 13 years the HRs were 1.09 (95% CI 1.04-1.14) and 1.14 (95% CI 1.09-1.19) per z-score, respectively. Children who were persistently taller or heavier than average, had increased risk of colon cancer. Similarly, growing taller or gaining more weight than average was positively associated with colon cancer. No associations were observed between BMI or height and rectal cancer. Childhood BMI and height, along with above average change during childhood are significantly and positively associated with adult colon cancers, but not with rectal cancer, suggesting different etiologies.

High body mass index is associated with impaired cognitive control

The prevalence of weight problems is increasing worldwide. There is growing evidence that high body mass index (BMI) is associated with frontal lobe dysfunction and cognitive deficits concerning mental flexibility and inhibitory control efficiency. The present study aims at replicating and extending these observations. We compared cognitive control performance of normal weight (BMI < 25) and overweight (BMI ≥ 25) university students on a task tapping either inhibitory control (Experiment 1) or interference control (Experiment 2). Experiment 1 replicated previous findings that found less efficient inhibitory control in overweight individuals. Experiment 2 complemented these findings by showing that cognitive control impairments associated with high BMI also extend to the ability to resolve stimulus-induced response conflict and to engage in conflict-driven control adaptation. The present results are consistent with and extend previous literature showing that high BMI in young, otherwise healthy individuals is associated with less efficient cognitive control functioning.

Metabolic predispositions and increased risk of colorectal adenocarcinoma by anatomical location: a large population-based cohort study in Norway

Whether different definitions of metabolic syndrome (MetS) are differently associated with colorectal adenocarcinoma (CA) by anatomical location is unclear. A population-based cohort study, the Cohort of Norway (CONOR) Study, was conducted in Norway from 1995 to 2010. Anthropometric measurements, blood samples, and lifestyle data were collected at recruitment. CAs were identified through linkage to the Norwegian Cancer Register. A composite index of MetS as defined by the International Diabetes Federation (IDF) or/and the National Cholesterol Education Program's Adult Treatment Panel III (ATP III) and single components of MetS, including anthropometric factors, blood pressure, lipids, triglycerides, and glucose, were analyzed. Cox proportional hazards regression was performed to estimate hazard ratios and 95% confidence intervals. Significant associations between single MetS components and CA, except for reduced high-density lipoprotein cholesterol and nonfasting glucose levels, were observed. MetS defined by 2 criteria separately showed a similar association with CA in general, and MetS defined by both the IDF and ATP III showed consistent results. Stronger associations were observed in the proximal colon among men (IDF: hazard ratio (HR) = 1.51, 95% confidence interval (CI): 1.24, 1.84; ATP III: HR = 1.40, 95% CI: 1.15, 1.70) and in the rectum among women (IDF: HR = 1.42, 95% CI: 1.07, 1.89; ATP III: HR = 1.43, 95% CI: 1.08, 1.90).

Elevated body mass index and maintenance of cognitive function in late life: exploring underlying neural mechanisms

BACKGROUND

Obesity is associated with vascular risk factors that in turn, may increase dementia risk. However, higher body mass index (BMI) in late life may be neuroprotective. The possible neural mechanisms underlying the benefit of higher BMI on cognition in older adults are largely unknown. Thus, we used functional connectivity magnetic resonance imaging (fcMRI) to examine: (1) the relationship between BMI and functional brain connectivity; and (2) the mediating role of functional brain connectivity in the association between baseline BMI and change in cognitive function over a 12-month period.

METHODS

We conducted a 12-month, prospective study among 66 community-dwelling older adults, aged 70 to 80 years, who were categorized as: normal weight (BMI from 18.50 to 24.99); overweight (BMI from 25.00 to 29.99); and obese (BMI ≥ 30.00). At baseline, participants performed a finger-tapping task during fMRI scanning. Relevant neural networks were initially identified through independent component analysis (ICA) and subsequently examined through seed-based functional connectivity analysis. At baseline and 12-months, we measured three executive cognitive processes: (1) response inhibition; (2) set shifting; and (3) working memory.

RESULTS

Obese individuals showed lower task-related functional connectivity during finger tapping in the default mode network (DMN) compared with their healthy weight counterparts (p < 0.01). Lower task-related functional connectivity in the DMN at baseline was independently associated with better working memory performance at 12-months (p = 0.02). Finally, DMN functional connectivity during finger tapping significantly mediated the relationship between baseline BMI and working memory at 12-months (indirect effect: -0.155, 95% confidence interval [-0.313, -0.053]).

CONCLUSIONS

These findings suggest that functional connectivity of the DMN may be an underlying mechanism by which higher BMI confers protective effects to cognition in late life.

Mendelian randomization study of height and risk of colorectal cancer

BACKGROUND

For men and women, taller height is associated with increased risk of all cancers combined. For colorectal cancer (CRC), it is unclear whether the differential association of height by sex is real or is due to confounding or bias inherent in observational studies. We performed a Mendelian randomization study to examine the association between height and CRC risk.

METHODS

To minimize confounding and bias, we derived a weighted genetic risk score predicting height (using 696 genetic variants associated with height) in 10,226 CRC cases and 10,286 controls. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (95% CI) for associations between height, genetically predicted height and CRC.

RESULTS

Using conventional methods, increased height (per 10-cm increment) was associated with increased CRC risk (OR = 1.08, 95% CI = 1.02-1.15). In sex-specific analyses, height was associated with CRC risk for women (OR = 1.15, 95% CI = 1.05-1.26), but not men (OR = 0.98, 95% CI = 0.92-1.05). Consistent with these results, carrying greater numbers of (weighted) height-increasing alleles (per 1-unit increase) was associated with higher CRC risk for women and men combined (OR = 1.07, 95% CI = 1.01-1.14) and for women (OR = 1.09, 95% CI =  .01-1.19). There was weaker evidence of an association for men (OR = 1.05, 95% CI = 0.96-1.15).

CONCLUSION

We provide evidence for a causal association between height and CRC for women. The CRC-height association for men remains unclear and warrants further investigation in other large studies.

Body mass index at early adulthood, subsequent weight change and cancer incidence and mortality

Obesity later in adulthood is associated with increased risks of many cancers. However, the effect of body fatness in early adulthood, and change in weight from early to later adulthood on cancer risk later in life is less clear. We used data from 13,901 people aged 45-64 in the Atherosclerosis Risk in Communities cohort who at baseline (1987-1989) self-reported their weight at the age of 25 and had weight and height measured. Incident cancers were identified through 2006 and cancer deaths were ascertained through 2009. Multivariable Cox proportional hazard models were used to relate body mass index (BMI) at age 25 and percent weight change from age 25 to baseline to cancer incidence and mortality. After adjusting for weight change from age 25 until baseline, a 5 kg/m(2) increment in BMI at age 25 was associated with a greater risk of incidence of all cancers in women [hazard ratio (95% confidence interval): 1.10 (1.02-1.20)], but not in men. Associations with incident endometrial cancer were strong [1.83 (1.47-2.26)]. After adjusting for BMI at age 25, a 5% increment in weight from age 25 to baseline was associated with a greater risk of incident postmenopausal breast cancer [1.05 (1.02-1.07)] and endometrial cancer [1.09 (1.04-1.14)] in women and incident colorectal cancer [1.05 (1.00-1.10)] in men. Excess weight during young adulthood and weight gain from young to older adulthood may be independently associated with subsequent cancer risk. Excess weight and weight gain in early adulthood should be avoided.

Associations between dietary fiber and colorectal polyp risk differ by polyp type and smoking status

The association of dietary fiber intake with colorectal cancer risk is established. However, the association may differ between cigarette smokers and nonsmokers. We evaluated this hypothesis in a large colonoscopy-based case-control study. Dietary fiber intakes were estimated by self-administered food frequency questionnaire. Unconditional logistic regression analysis was used to estimate ORs and 95% CIs with adjustment for potential confounders. Analysis also was stratified by cigarette smoking and sex. High dietary fiber intake was associated with reduced risk of colorectal polyps (P-trend = 0.003). This association was found to be stronger among cigarette smokers (P-trend = 0.006) than nonsmokers (P-trend = 0.21), although the test for multiplicative interaction was not statistically significant (P = 0.11). This pattern of association was more evident for high-risk adenomatous polyps (ADs), defined as advanced or multiple ADs (P-interaction smoking and dietary fiber intake = 0.09). Among cigarette smokers who smoked ≥23 y, a 38% reduced risk of high-risk ADs was found to be associated with high intake of dietary fiber compared with those in the lowest quartile fiber intake group (P-trend = 0.004). No inverse association with dietary fiber intake was observed for low-risk ADs, defined as single nonadvanced ADs. Cigarette smoking may modify the association of dietary fiber intake with the risk of colorectal polyps, especially high-risk ADs, a well-established precursor of colorectal cancer.

Body mass index and death rate of colorectal cancer among a national cohort of U.S. adults

Substantial evidence suggests that increasing adiposity is associated with an increased death rate of colorectal cancer, but no studies were conducted among national representative populations in the United States. The current study examined the death rate across BMI levels in 7,016 adults who participated in the National Health and Nutrition Examination Survey in 1971-1975. BMI categories were defined as normal (18.5-24.9 kg/m(2)), overweight (25-29.9), and obese (≥30). A total of 519 cancer deaths were identified during a 17-yr follow-up with 118,998 person-years. No significantly increased death rates of total cancers, lung, breast, and prostate cancer were observed among participants with an increased BMI. However, colorectal cancer death rates were 0.39, 0.68, and 0.96/1,000 person-years, respectively, for normal weight, overweight, and obese (P value for log-rank trend test < 0.001), and the corresponding adjusted hazard ratios [95% confidence intervals (CI)] were 1.00 (reference), 1.25 (95% CI = 0.72-2.19), and 2.04 (1.08-3.83), respectively. No gender difference of the association was identified. The authors conclude that a significantly increased death rate of colorectal cancer was associated with excess body weight. The current study is an addition to the expanding body of literature indicating an increased risk of colorectal cancer development among the obese.

Cigarette smoking, genetic variants in carcinogen-metabolizing enzymes, and colorectal cancer risk

The risk of colorectal cancer associated with smoking is unclear and may be influenced by genetic variation in enzymes that metabolize cigarette carcinogens. The authors examined the colorectal cancer risk associated with smoking and 26 variants in carcinogen metabolism genes in 1,174 colorectal cancer cases and 1,293 population-based controls recruited in Canada by the Ontario Familial Colorectal Cancer Registry from 1997 to 2001. Adjusted odds ratios were calculated by multivariable logistic regression. Smoking for >27 years was associated with a statistically significant increased colorectal cancer risk (adjusted odds ratio (AOR) = 1.25, 95% confidence interval (CI): 1.02, 1.53) in all subjects. Colorectal cancer risk associated with smoking was higher in males for smoking status, duration, and intensity. The CYP1A1-3801-CC (AOR = 0.47, 95% CI: 0.23, 0.94) and CYP2C9-430-CT (AOR = 0.82, 95% CI: 0.68, 0.99) genotypes were associated with decreased risk, and the GSTM1-K173N-CG (AOR = 1.99, 95% CI: 1.21, 3.25) genotype was associated with an increased risk of colorectal cancer. Statistical interactions between smoking and genetic variants were assessed by comparing logistic regression models with and without a multiplicative interaction term. Significant interactions were observed between smoking status and SULT1A1-638 (P = 0.02), NAT2-857 (P = 0.01), and CYP1B1-4390 (P = 0.04) variants and between smoking duration and NAT1-1088 (P = 0.02), SULT1A1-638 (P = 0.04), and NAT1-acetylator (P = 0.03) status. These findings support the hypothesis that prolonged cigarette smoking is associated with increased risk of colorectal cancer and that this risk may be modified by variation in carcinogen metabolism genes.

The association between cigarette smoking and risk of colorectal cancer in a large prospective cohort from the United States

BACKGROUND

Many studies have reported a 20% to 60% increase in risk of colorectal cancer associated with active smoking. However, neither the U.S. Surgeon General nor the IARC have classified the relationship as causal because of concern about residual confounding.

METHODS

In a prospective study of 184,187 people followed from 1992 to 2005, we used Cox proportional hazard models to examine the relationship of cigarette smoking to incident colorectal cancer, controlling for screening and multiple known and putative risk factors. Information on smoking and time-varying covariates was updated in 1997, 1999, 2001, and 2003.

RESULTS

The incidence of colorectal cancer was significantly higher in current [hazard ratios (HR), 1.27; 95% confidence intervals (CI), 1.06-1.52] and former smokers (HR, 1.23; 95% CI, 1.11-1.36) compared with lifelong nonsmokers in analyses that controlled for 13 covariates, including screening. The relative risk was greatest among current smokers with at least 50 years of smoking (HR, 1.38; 95% CI, 1.04-1.84). Among former smokers, risk of colorectal cancer decreased with greater time since cessation (P trend = 0.0003), and also decreased with earlier age at cessation (P trend = 0.0014). No association was seen among former smokers who had quit before age of 40 years or abstained for 31 years or more.

CONCLUSIONS

Long-term cigarette smoking is associated with colorectal cancer, even after controlling for screening and multiple other risk factors.

Obesity as a risk factor for coronary events in Japanese patients with hypercholesterolemia on low-dose simvastatin therapy

AIM

We previously reported that obesity (defined as a body mass index (BMI) >or=25 kg/m(2)) was not an independent risk factor for coronary heart disease (CHD) in hypercholesterolemic patients without a history of CHD from the Japan Lipid Intervention Trial (J-LIT). In this study, the obese J-LIT subgroup was further analyzed to assess CHD risk.

METHODS

In the J-LIT study, patients received simvastatin treatment (usually at 5 mg/day) for 6 years. A total of 38,385 patients (mean age: 57.7+/-7.9, 12,111 men) without prior CHD and/or stroke were analyzed.

RESULTS

In this cohort, 181 CHD (acute myocardial infarction or sudden cardiac death) were observed. Obesity (n=12,929) was not an independent risk factor for CHD (relative risk; 1.18, 95% confidence interval; 0.87?1.59) after adjustment for the major risk known factors, such as age, sex, hypertension, diabetes mellitus (DM), and smoking. However, blood pressure, triglycerides, and fasting plasma glucose all increased, while high-density lipoprotein-cholesterol decreased, with increased BMI. The percentage of patients having two or three risk factors (such as dyslipidemia, hypertension, and DM) also increased with increased BMI.

CONCLUSIONS

Obesity was not an independent risk factor for CHD in hypercholesterolemic patients on statin therapy; however, it is important to control obesity, a condition in which CHD risks accumulate, in order to improve associated risk factors along with the treatment of each risk factor, thus further reducing the risk of CHD.

Interaction of molecular markers and physical activity on mortality in patients with colon cancer

PURPOSE

Physical activity in colon cancer survivors has been associated with lower cancer recurrences and improved survival. Whether molecular features of the tumor portend more or less likelihood for benefit from exercise is unknown.

EXPERIMENTAL DESIGN

Using two large prospective cohort studies with physical activity assessments after colon cancer diagnosis, we examined expression of fatty acid synthase, p53, p21, and p27 and mutational status of K-ras and phosphatidylinositol 3-kinase(PI3KCA). We calculated hazard ratios (HR) of colon cancer-specific mortality, adjusted for tumor and patient characteristics, and tested for molecular interactions with exercise.

RESULTS

In a cohort of 484 men and women with stage I to III colon cancer, patients who engaged in at least 18 metabolic equivalent task (MET)-hours per week after diagnosis had an adjusted HR for colon cancer-specific mortality of 0.64 [95% confidence interval (95% CI), 0.33-1.23] and for overall mortality of 0.60 (95% CI, 0.41-0.86). A statistically significant interaction was detected based on p27 expression (P = 0.03). For tumors with loss of p27 (n = 195), physical activity of > or =18 MET-hours/week led to a HR for colon cancer mortality of 1.40 (95% CI, 0.41-4.72), compared with those with <18 MET-hours/week. However, for tumors with expression of p27 (n = 251), the adjusted HR was 0.33 (95% CI, 0.12-0.85). Molecular status of fatty acid synthase, K-ras, p53, p21, and PI3KCA did not influence the association between exercise and colon cancer-specific or overall mortality.

CONCLUSION

The benefit of physical activity on outcomes in patients with stage I to III colon cancer may be influenced by p27 status. Further studies are warranted to confirm these findings.

Examining the association between cigarette smoking and colorectal cancer using historical case-control data

BACKGROUND

The majority of recent, well-designed studies have shown that long-term cigarette smoking increases colorectal cancer risk, but older studies with shorter durations of exposure often found no association. This study aimed to examine colorectal cancer risk by smoking exposure using data collected in the late-1950s and early-1960s.

METHODS

This case-control study examined colorectal cancer risk by lifetime smoking history. There were 1365 patients who visited Roswell Park Cancer Institute (RPCI) between 1957 and 1965 diagnosed with primary, incident colorectal cancers that were matched to 4096 malignancy-free controls on gender and age. Odds ratios were calculated using separate logistic regression models for each smoking exposure, while controlling for other tobacco use, county of residence, race, age, gender, and body mass index (BMI).

RESULTS

The adjusted OR for individuals who reported their greatest level of smoking to be more than 1 pack/day was 0.87 (95% CI=0.67-1.15). Among those who smoked 42 or more years, the adjusted OR was 0.89 (95% CI=0.68-1.15) compared to those who never smoked. For individuals who smoked more than 45 pack-years, the OR was 0.92 (95% CI=0.72-1.19). The results did not differ significantly by gender, although men had considerably greater exposure compared to women. Results also did not differ by colorectal sub-site.

CONCLUSION

No association was found between long-term cigarette smoking and colorectal cancer risk. These results are in accord with studies that followed cohorts throughout the 1950s and 1960s. Methodological limitations, such as missing data on covariates and the higher incidence of smoking-related illness in a hospital setting, may have contributed to the null results found in this study. Prolonged population exposure to cigarettes and perhaps a changing product may explain why more recent studies have reported a positive association between smoking and colorectal cancer.

Lifestyle factors and colorectal cancer risk (1): systematic review and meta-analysis of associations with body mass index

OBJECTIVE

Excess body weight, defined by body mass index (BMI), may increase the risk of colorectal cancer. As a prerequisite to the determination of lifestyle attributable risks, we undertook a systematic review and meta-analysis of prospective observational studies to quantify colorectal cancer risk associated with increased BMI and explore for differences by gender, sub-site and study characteristics.

METHOD

We searched MEDLINE and EMBASE (to December 2007), and other sources, selecting reports based on strict inclusion criteria. Random-effects meta-analyses and meta-regressions of study-specific incremental estimates were performed to determine the risk ratio (RR) and 95% confidence intervals (CIs) associated with a 5 kg/m(2) increase in BMI.

RESULTS

We analysed 29 datasets from 28 articles, including 67,361 incident cases. Higher BMI was associated with colon (RR 1.24, 95% CIs: 1.20-1.28) and rectal (1.09, 1.05-1.14) cancers in men, and with colon cancer (1.09, 1.04-1.12) in women. Associations were stronger in men than in women for colon (P < 0.001) and rectal (P = 0.005) cancers. Associations were generally consistent across geographic populations. Study characteristics and adjustments accounted for only moderate variations of associations.

CONCLUSION

Increasing BMI is associated with a modest increased risk of developing colon and rectal cancers, but this modest risk may translate to large attributable proportions in high-prevalence obese populations. Inter-gender differences point to potentially important mechanistic differences, which merit further research.

Cigarette smoking and the risk of colorectal cancer: a meta-analysis of prospective cohort studies

BACKGROUND & AIMS

Smoking has been implicated in many malignant diseases, but its association with colorectal cancer (CRC) is controversial. We quantitatively evaluated the relation between smoking and incidence of CRC in a meta-analysis of cohort studies.

METHODS

Full publications of prospective cohort studies were identified in MEDLINE and EMBASE from 1950 to 2008. Subjects were classified as current smokers, former smokers, or never smokers. The quantity of smoking was assessed by number of cigarettes per day, years of smoking, and pack-years. The reported relative risks of CRC were pooled by random-effects model. Sensitivity analysis was conducted, and publication bias was evaluated.

RESULTS

A total of 1,463,796 subjects were recruited in 28 prospective cohorts from America, Europe, and Asia, with median follow-up of 13 years (range, 4-30 years). Current smokers showed a modestly higher risk of CRC (relative risk [RR], 1.20; 95% confidence interval [CI], 1.10-1.30) than never smokers. The risk of CRC among male smokers (RR, 1.38; 95% CI, 1.22-1.56) was more significant than among female smokers (RR, 1.06; 95% CI, 0.95-1.19). Rectal cancer was more closely related to smoking (RR, 1.36; 95% CI, 1.15-1.61) than colonic cancer. Former smokers still carried a higher CRC risk than never smokers. The increased risk of CRC was related to cigarettes per day, longer years of smoking, or larger pack-years.

CONCLUSIONS

Smoking was associated with a significantly increased risk of CRC. The associated risk was higher for men and for rectal cancers. The association of tobacco consumption and CRC risk appeared to be dose-related.

The impact of dietary and lifestyle risk factors on risk of colorectal cancer: a quantitative overview of the epidemiological evidence

Colorectal cancer is a major cause of cancer mortality and is considered to be largely attributable to inappropriate lifestyle and behavior patterns. The purpose of this review was to undertake a comparison of the strength of the associations between known and putative risk factors for colorectal cancer by conducting 10 independent meta-analyses of prospective cohort studies. Studies published between 1966 and January 2008 were identified through EMBASE and MEDLINE, using a combined text word and MESH heading search strategy. Studies were eligible if they reported estimates of the relative risk for colorectal cancer with any of the following: alcohol, smoking, diabetes, physical activity, meat, fish, poultry, fruits and vegetables. Studies were excluded if the estimates were not adjusted at least for age. Overall, data from 103 cohort studies were included. The risk of colorectal cancer was significantly associated with alcohol: individuals consuming the most alcohol had 60% greater risk of colorectal cancer compared with non- or light drinkers (relative risk 1.56, 95% CI 1.42-1.70). Smoking, diabetes, obesity and high meat intakes were each associated with a significant 20% increased risk of colorectal cancer (compared with individuals in the lowest categories for each) with little evidence of between-study heterogeneity or publication bias. Physical activity was protective against colorectal cancer. Public-health strategies that promote modest alcohol consumption, smoking cessation, weight loss, increased physical activity and moderate consumption of red and processed meat are likely to have significant benefits at the population level for reducing the incidence of colorectal cancer.

Cigarette smoking and colorectal cancer incidence and mortality: systematic review and meta-analysis

The association between cigarette smoking and colorectal cancer (CRC) has been controversial. To synthesize the available data, we conducted a comprehensive meta-analysis of all prospective studies. A total of 36 studies were included in our meta-analysis. We examined the association between smoking and CRC, colon cancer and rectal cancer in terms of incidence and mortality. Separate analyses were conducted for smoking status, daily cigarette consumption, duration, pack-years and age of initiation. Relative to nonsmokers, current and former smokers had a significantly increased risk of CRC incidence and mortality, respectively. When CRC data were combined with colon/rectal cancer data, current smokers had a significantly increased risk of CRC incidence. All 4 dose-response variables examined-daily cigarette consumption (RR = 1.38 for an increase of 40 cigarettes/day), duration (RR = 1.20 for an increase of 40 years of duration), pack-years (RR = 1.51 for an increase of 60 pack-years) and age of initiation (RR = 0.96 for a delay of 10 years in smoking initiation)-were significantly associated with CRC incidence (all p-values < 0.0001). The relationship between duration of smoking and rectal cancer incidence was also significant. Among the subset of studies that distinguished cancer by site, a higher risk was seen for rectal cancer than for colon cancer for all analyses. Among prospective studies, a consistent association exists between smoking and CRC. The association is stronger for rectal cancer than for colon cancer in the subset of studies that differentiated cancer by site.

Adult height and the risks of cardiovascular disease and major causes of death in the Asia-Pacific region: 21,000 deaths in 510,000 men and women

BACKGROUND

In Caucasian populations, adult height is inversely associated with cardiovascular disease (CVD) risk and positively related to some cancers. However, there are few data from Asian populations and from women. We sought to determine the sex- and region-specific associations between height and cardiovascular outcomes, and deaths due to cancer, respiratory and injury in populations from the Asia-Pacific region.

METHODS

Thirty-nine studies from the Asia Pacific Cohort Studies Collaboration database were included. We used Cox proportional hazard regression models to estimate the associations between height and pre-specified outcomes.

RESULTS

A total of 510,800 participants with 21,623 deaths were included. Amongst men, inverse linear associations were observed between height and coronary heart disease (CHD), stroke, CVD, injury and total mortality. The hazard ratios [95% confidence intervals, (CI)] for a 1-SD (= 6 cm) increment in height ranged from 0.85 (0.80-0.91) for injury to 0.97 (0.95-0.98) for total mortality. Similar trends were found between height and CHD, haemorrhagic stroke and CVD in women. A positive linear association was observed between height and cancer mortality. For each standard deviation greater height, the risk of cancer was increased by 5% (2-8%) and 9% (5-14%) in men and women, respectively. No regional difference was observed between Asian and Australasian cohorts. Adjusting for markers of education did not alter the results.

CONCLUSIONS

The opposing relationships of height with CVD and cancer suggest that care is required in setting national policies on childhood nutrition lest they have unintended consequences on the incidence of major non-communicable diseases.

An association between colonic adenoma and abdominal obesity: a cross-sectional study

BACKGROUND

Colorectal adenoma is a precursor lesion of colorectal cancer and thus, it is an important target for preventing colorectal cancer. Only a few studies suggest an association between colorectal adenoma and obesity, but results show considerable heterogeneity. In this study, we investigated the association between colorectal adenoma and waist circumference.

METHODS

165 adenoma cases and 365 polyp-free controls with a normal colon were compared in this cross-sectional study. Subjects underwent screening colonoscopy by experienced endoscopists. Demographic data, including smoking habit, were obtained by interview and waist circumference and anthropometric measurements were examined. Dietary intakes were evaluated using a food frequency questionnaire, and abdominal obesity was evaluated by measuring waist circumference. Statistical analysis was performed using SPSS for 13.0.

RESULTS

Age, waist circumference, and BMI were significantly higher in cases than controls. And smokers and men were more prevalent among cases than controls.Among the abdominal obese subjects, 45.6% had 1 or more adenoma, and 9.0% of these had advanced adenoma, whereas among subjects with a normal waist circumference, only 25.7% had 1 or more adenomas. The prevalence of adenoma was higher among abdominal obese group (P < 0.05). Logistic regression analysis showed that abdominal obesity was associated with an increased risk of colorectal adenoma (OR, 2.74; 95% CI, 1.66~4.51 in men, OR, 2.58; 95% CI, 1.08~6.12 in women). These associations persisted even after adjusting for BMI. While BMI was found to be weekly associated with the risk of adenoma among men at the highest BMI levels. However, BMI was not associated with the risk for adenoma after adjusting for waist circumference.

CONCLUSION

Our data suggest that abdominal obesity is associated with an increased risk of colorectal adenoma.

Lifestyle, genes, and cancer

It is estimated that almost 1.5 million people in the USA are diagnosed with cancer every year. However, due to the substantial effect of modifiable lifestyle factors on the most prevalent cancers, it has been estimated that 50% of cancer is preventable. Physical activity, weight loss, and a reduction in alcohol use can strongly be recommended for the reduction of breast cancer risk. Similarly, weight loss, physical activity, and cessation of tobacco use are important behavior changes to reduce colorectal cancer risk, along with the potential benefit for the reduction of red meat consumption and the increase in folic acid intake. Smoking cessation is still the most important prevention intervention for reducing lung cancer risk, but recent evidence indicates that increasing physical activity may also be an important prevention intervention for this disease. The potential benefit of lifestyle change to reduce prostate cancer risk is growing, with recent evidence indicating the importance of a diet rich in tomato-based foods and weight loss. Also, in the cancers for which there are established lifestyle risk factors, such as physical inactivity for breast cancer and obesity for colorectal cancer, there is emerging information on the role that genetics plays in interacting with these factors, as well as the interaction of combinations of lifestyle factors. Integration of genetic information into lifestyle factors can help to clarify the causal relationships between lifestyle and genetic factors and assist in better identifying cancer risk, ultimately leading to better-informed choices about effective methods to enhance health and prevent cancer.

Obesity and cancer

The prevalence of obesity, defined as a BMI of > or =30.0 kg/m2, has increased substantially over previous decades to about 20% in industrialized countries, and a further increase is expected in the future. Epidemiological studies have shown that obesity is a risk factor for: post-menopausal breast cancer; cancers of the endometrium, colon and kidney; malignant adenomas of the oesophagus. Obese subjects have an approximately 1.5-3.5-fold increased risk of developing these cancers compared with normal-weight subjects, and it has been estimated that between 15 and 45% of these cancers can be attributed to overweight (BMI 25.0-29.9 kg/m2) and obesity in Europe. More recent studies suggest that obesity may also increase the risk of other types of cancer, including pancreatic, hepatic and gallbladder cancer. The underlying mechanisms for the increased cancer risk as a result of obesity are unclear and may vary by cancer site and also depend on the distribution of body fat. Thus, abdominal obesity as defined by waist circumference or waist:hip ratio has been shown to be more strongly related to certain cancer types than obesity as defined by BMI. Possible mechanisms that relate obesity to cancer risk include insulin resistance and resultant chronic hyperinsulinaemia, increased production of insulin-like growth factors or increased bioavailability of steroid hormones. Recent research also suggests that adipose tissue-derived hormones and cytokines (adipokines), such as leptin, adiponectin and inflammatory markers, may reflect mechanisms linked to tumourigenesis.

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.

[Nutritional and antioxidant status of colorectal cancer patients]

INTRODUCTION

Oxidative stress is one of the risk factors of colorectal carcinogenesis. In inflammatory reactions the activated leucocytes product mutagenic and mitogenic free radicals, hereby promoting tumor formation. Obesity, hyperlipidemia and hyperinsulinemia increases the energy supply of epithelial cells, thus leads to deregulation of mitochondrial electron transport chain. The latter leads to increased free radical production that causes troubles in cell cycle regulation, mutations, and unrestricted proliferation of damaged cells.

AIM

Evaluation of some parameters of antioxidant and nutritional status in patients with benign or malignant colorectal neoplasm.

METHODS

Assessment of nutrient intake, measurement of some anthropometric parameters (body height, body weight, waist, hip and arm circumference, waist/hip ratio), determination of serum prealbumin level, evaluation of the biomarkers of antioxidant status (superoxide dismutase and glutathione peroxidase activity, levels of uric acid and albumin, total antioxidant status, free radical scavenger capacity), determination the concentration of oxidated product and malondialdehyde.

RESULTS

In patients with malignant tumor the dietary fiber, folate and vitamin A intake was under the optimal level, and the serum prealbumin concentration was lower than in patients with benign lesion. There was a high incidence of overweight and obesity among patients. Significant difference was found between diseased subjects and healthy controls in terms of the biomarkers of antioxidant status, such as free radical scavenger capacity, concentration of advanced oxidation protein products and malondialdehyde, glutathione peroxidase activity.

CONCLUSIONS

The insufficient folate and vitamin A intake, the high incidence of overweight and obesity, and the abnormal values of the biomarkers of antioxidant status observed in the study groups seem to support the correlation between colorectal tumor, nutritional and antioxidant status.

A prospective cohort study of rectal cancer risk in relation to active cigarette smoking and passive smoke exposure

PURPOSE

The present investigation prospectively examined active cigarette smoking and household passive smoke exposure and the risk of developing rectal cancer.

METHODS

Cigarette smoking data were collected on all household members during two private censuses in Washington County, Maryland. These two cohorts were followed up, one cohort from 1963-1978 and the other from 1975-1994 for first-time diagnoses of rectal cancer. We identified 148 and 169 rectal cancer cases in the 1963 and 1975 cohorts, respectively. Relative risks were estimated by means of Poisson regression models.

RESULTS

In men, the adjusted relative risks (aRR) and 95% confidence intervals (CI) for the association between current smoking and rectal cancer were 3.1 (1.2-7.8) in the 1963 cohort and 1.8 (0.9-3.7) in the 1975 cohort; the corresponding aRRs in women were 0.9 (0.5-1.8) and 1.6 (0.9-3.8) in the 1963 and 1975 cohorts, respectively. In nonsmokers, household passive smoke exposure was strongly associated with rectal cancer among men in the 1963 cohort (aRR = 5.8; 1.8-18.4) but not the 1975 cohort (aRR = 1.1; 0.2-5.0). In women, household passive exposure was not strongly associated with rectal cancer in either cohort.

CONCLUSIONS

The results of our study suggest that active cigarette smoking may contribute to rectal cancer risk, but inconsistencies in the findings preclude drawing strong, clear-cut inferences.

Body size and composition and colon cancer risk in women

Studies of colon cancer risk in males have reported strong positive associations with obesity, particularly with central adiposity. The association has been weaker and less consistent for women. In a prospective cohort study of women, body measurements were taken directly; fat mass and fat-free mass being estimated by bioelectrical impedance analysis and central adiposity by waist circumference and waist-to-hip ratio (WHR). Among 24,072 women followed on average for 10.4 years, 212 colon cancers were ascertained via the population cancer registry. We reviewed medical records of all cases and classified them according to anatomic site and stage. The central adiposity measures of WHR (hazard ratio per 0.1 unit increase = 1.31, 95% confidence interval (CI) 1.08-1.58) and waist circumference (hazard ratio per 10 cm increase = 1.14, 95% CI 1.02-1.28) were positively associated with colon cancer risk. There was little or no association between other anthropometric measures and risk of colon cancer. There was some evidence that the associations were stronger for proximal tumors, but no evidence that risk differed by stage for any of the anthropometric measures. Central adiposity appears to be associated with colon cancer risk in women.

Do Factors Related to Endogenous and Exogenous Estrogens Modify the Relationship between Obesity and Risk of Colorectal Adenomas in Women?

Obesity has consistently been associated with increased colorectal cancer risk in men, but not in women. In the absence of postmenopausal hormone use (PMH), adipose-derived estrogen is the primary determinant of circulating estrogen levels in postmenopausal women, perhaps ameliorating the mitogenic effects of obesity in this group. Using data from a case-control study in the United States, we examined associations among obesity, potential modifying effects of factors related to endogenous and exogenous estrogen levels, and risk of colorectal adenoma. Cases (n = 219) were women of ages 30 to 74 years with colonoscopy proven, incident, sporadic, pathology-confirmed, adenomatous polyps of the colon and rectum. Two control groups were recruited: colonoscopy-confirmed polyp-free women (n = 438) and age- and zip code frequency-matched women randomly selected from the community (n = 247). Multivariate odds ratios and 95% confidence intervals (95% CI) for obese [body mass index (BMI) >or=30.0; compared with nonobese, BMI <25.0] premenopausal women were 2.09 (95% CI, 0.81-5.41) versus colonoscopy controls, and 5.18 (95% CI, 1.40-19.32) versus population controls. For PMH users, the corresponding odds ratios were 0.29 (95% CI, 0.12-0.70) versus colonoscopy controls and 0.64 (95% CI, 0.23-1.83) versus population controls. There was no significant association of BMI with adenoma risk for PMH nonusers. Findings for waist-to-hip ratio were similar to those for BMI. These data support the hypothesis that risk for colorectal adenoma may be increased with obesity among premenopausal women but decreased among postmenopausal women, especially if they also take PMH.

Cigarette smoking and the risk of colorectal cancer among men: a prospective study in Japan

The association between cigarette smoking and the risk of colorectal cancer remains controversial. We examined this association using a population-based prospective cohort study in Miyagi, Japan. In 1990, we delivered a self-administered questionnaire on cigarette smoking and other health habits to 25 279 men who were 40-64 years of age and lived in 14 municipalities of Miyagi Prefecture. A total of 22 836 men responded (90.3% response rate). During 7 years of follow-up (158 376 person-years), we identified 188 patients of colorectal cancer. Relative risks and 95% confidence intervals were estimated by the Cox proportional-hazards regression analysis with adjustment for potential confounders. The multivariate-adjusted relative risks (95% confidence interval) of colorectal cancer for past smokers and current smokers compared with those who had never smoked were 1.73 (1.04-2.87) and 1.47 (0.93-2.34), respectively. Among current smokers, both a higher number of cigarettes smoked per day and an earlier age at which smoking had started were associated with a significant linear increase in risk (P for trend <0.05). Our findings are consistent with the hypothesis that cigarette smoking is associated with a higher risk of colorectal cancer in men.

Metabolic syndrome and gastrointestinal diseases

Metabolic syndrome is a cluster of metabolic abnormalities consisting essentially of obesity, especially abdominal obesity. Metabolic syndrome has been highlighted as a risk factor for cardiovascular and other chronic diseases. Obesity has been implicated in various gastrointestinal diseases such as gastroesophageal reflux diseases and colorectal cancer. Recently, abdominal obesity has been shown to be more important than obesity as expressed by an elevated body mass index as a causative factor for the development of these diseases. In addition to the mechanical effects of obesity, such as an increase in intra-abdominal pressure from large amounts of adipose tissue, substances that adipose tissues secrete, such as tumor necrosis factor-alpha, interleukin-6, leptin, and insulin-like growth factor-1, have been proposed to be pathogenic links to these diseases. In this review, we discuss the association of metabolic syndrome or the individual components of metabolic syndrome, focusing on obesity and abdominal obesity, with gastrointestinal diseases.

Body size and composition and risk of rectal cancer (Australia)

BACKGROUND

Although body mass index has been shown to be associated with colon cancer, studies of rectal cancer risk have generally reported no association. The relationship between rectal cancer risk and central adiposity, overall fat mass, and fat-free mass is unknown.

METHODS

In a prospective cohort study of people aged 27-75 years, body measurements were taken directly; fat mass and fat-free mass being estimated by bioelectrical impedance analysis and central adiposity by waist circumference and waist-to-hip ratio. Among 16,867 men and 24,247 women followed on average for 10.3 years, 229 rectal cancers were ascertained via the population cancer registry.

RESULTS

When comparing the highest tertile with the lowest tertile, weight (hazard ratio = 1.4, 95% confidence interval (CI) 1.1-2.0), waist circumference (hazard ratio = 1.4, 95% CI 1.0-1.9), fat mass (hazard ratio = 1.4, 95% CI 1.0-2.0) and percent fat (hazard ratio = 1.4, 95% CI 1.0-2.0) were positively associated with rectal cancer risk. There was no evidence that risk differed by sex for any of the anthropometric measures.

CONCLUSIONS

Waist circumference and fat mass may be weakly related to risk of rectal cancer.

Body mass index, body height, and subsequent risk of colorectal cancer in middle-aged and elderly Japanese men and women: Japan public health center-based prospective study

OBJECTIVE

To investigate the association of body mass index (BMI) or body height with colorectal cancer incidence in a population-based prospective study.

METHODS

We identified 986 (626 men and 360 women) newly diagnosed cases of colorectal cancer during the 9.4-year follow-up of a cohort consisting of 102,949 (49,158 male and 53,791 female) middle-aged and elderly Japanese.

RESULTS

Lower BMI groups (lower than 23) were not associated with colorectal cancer compared with the 23-24.9 BMI group. Any categories of 25-26.9, 27-29.9, or 30 or more BMI were associated with an increased risk of colorectal cancer compared with the lower than 25 BMI (RR, 1.2 for 25-26.9, 1.4 for 27-29.9, and 1.5 for 30 or more; p for trend, 0.004) in men. These associations were more evident only in invasive-type cancer analysis. BMI was not associated with the risk of colorectal cancer in women. No significant association with height was obtained for either men or women.

CONCLUSIONS

The association of BMI with colorectal cancer was confirmed in a Japanese population as well as Western populations. Only invasive-cancer analysis suggested that BMI was important for tumor growth and proliferation. Approximately 6.7% of colorectal cancer was attributable to a BMI of 25 or higher in middle-aged and elderly Japanese men.

Body Size and Risk of Colon and Rectal Cancer in the European Prospective Investigation Into Cancer and Nutrition (EPIC)

BACKGROUND

Body weight and body mass index (BMI) are positively related to risk of colon cancer in men, whereas weak or no associations exist in women. This discrepancy may be related to differences in fat distribution between sexes or to the use of hormone replacement therapy (HRT) in women.

METHODS

We used multivariable adjusted Cox proportional hazards models to examine the association between anthropometric measures and risks of colon and rectal cancer among 368 277 men and women who were free of cancer at baseline from nine countries of the European Prospective Investigation Into Cancer and Nutrition. All statistical tests were two-sided.

RESULTS

During 6.1 years of follow-up, we identified 984 and 586 patients with colon and rectal cancer, respectively. Body weight and BMI were statistically significantly associated with colon cancer risk in men (highest versus lowest quintile of BMI, relative risk [RR] = 1.55, 95% confidence interval [CI] = 1.12 to 2.15; P(trend) = .006) but not in women. In contrast, comparisons of the highest to the lowest quintile showed that several anthropometric measures, including waist circumference (men, RR = 1.39, 95% CI = 1.01 to 1.93; P(trend) = .001; women, RR = 1.48, 95% CI = 1.08 to 2.03; P(trend) = .008), waist-to-hip ratio (WHR; men, RR = 1.51, 95% CI = 1.06 to 2.15; P(trend) = .006; women, RR = 1.52, 95% CI = 1.12 to 2.05; P(trend) = .002), and height (men, RR = 1.40, 95% CI = 0.99 to 1.98; P(trend) = .04; women, RR = 1.79, 95% CI = 1.30 to 2.46; P(trend)<.001) were related to colon cancer risk in both sexes. The estimated absolute risk of developing colon cancer within 5 years was 203 and 131 cases per 100,000 men and 129 and 86 cases per 100,000 women in the highest and lowest quintiles of WHR, respectively. Upon further stratification, no association of waist circumference and WHR with risk of colon cancer was observed among postmenopausal women who used HRT. None of the anthropometric measures was statistically significantly related to rectal cancer.

CONCLUSIONS

Waist circumference and WHR, indicators of abdominal obesity, were strongly associated with colon cancer risk in men and women in this population. The association of abdominal obesity with colon cancer risk may vary depending on HRT use in postmenopausal women; however, these findings require confirmation in future studies.

Birth characteristics and adult cancer incidence: Swedish cohort of over 11,000 men and women

Associations between larger size at birth and increased rates of adult cancer have been proposed but few empirical studies have examined this hypothesis. We investigated overall and site-specific cancer incidence in relation to birth characteristics in a Swedish population-based cohort of 11,166 singletons born in 1915-1929 for whom we have detailed obstetric data and who were alive in 1960. A total of 2,685 first primary cancers were registered during follow-up from 1960 to 2001. A standard deviation (SD) increase in birth weight for gestational age (GA) was associated with (sex-adjusted) increases of 13% (95% CI = 0.03-0.23) in the rates of digestive cancers and of 17% (95% CI = 0.01-0.35) in the rates of lymphatic cancers. Women who had higher birth weights also had increased rates of breast cancer under age 50 years (by 39% per SD increase; 95% CI = 0.09-0.79), but reduced rates (by 24%; 95% CI = 0.07-0.38) of endometrial (corpus uteri) cancer at all ages. There was no evidence of associations with other cancer sites. For overall cancer incidence, men had an 8% increased risk at all ages per SD increase in birth weight for GA while women only had an increased risk under age 50 years (mainly driven by the association with breast cancer). These findings provide evidence of a modest association of birth size and adult cancer risk, resulting from positive associations with a few cancer sites and a possible inverse association with endometrial cancer.

A prospective study of body size and colon cancer mortality in Japan: The JACC Study

OBJECTIVE

To determine whether body size measurements are risk factors for colon cancer death among the Japanese.

DESIGN AND SUBJECTS

A nationwide prospective study, the Japan Collaborative Cohort (JACC) Study from 1988 to 1999. The present analysis included 43 171 men and 58 775 women aged 40-79 y who respond to a questionnaire on current weight and height, weight around 20 y of age, and other lifestyle factors. Body mass index (BMI) at baseline and 20 y of age (B-BMI and 20-BMI, respectively) were calculated.

RESULTS

We identified 127 deaths from colon cancer during the follow-up of 424 698 person-years among men and 122 deaths during the follow-up of 591 787 person-years among women. After adjustments for the lifestyle factors known to modify the risk of colon cancer, weight at baseline showed a significant positive association in women, while no such association was seen in men. There was also a significant trend of increasing risk with the increase in B-BMI among women. Women with B-BMI >/=28 kg/m(2) had a relative risk (RR) of 3.41 (95% confidence interval (CI): 1.44-8.06) compared with those with BMI of 20-<22 kg/m(2). 20-BMI also presented the same trend of increasing risk as B-BMI. Women with 20-BMI of <22 and B-BMI of >26 kg/m(2), that is, excessive BMI gain, had a high RR of 3.41 (95% CI 1.29-9.02) compared with those with 20-BMI of <22 and B-BMI of <22 kg/m(2). There were no corresponding trends of colon cancer risk for B-BMI, 20-BMI, or BMI change among men.

CONCLUSIONS

These study data suggest that obesity and excessive weight gain are associated with the risk of colon cancer death in Japanese women but no such relationship was found in Japanese men.

Height, weight, and alcohol consumption in relation to the risk of colorectal cancer in Japan: a prospective study

Colorectal cancer incidence in relation to body size, smoking, and alcohol consumption was studied in a cohort of 29 051 city residents of Japan. In 1992, each participant completed a self-administered questionnaire on sociodemographic characteristics, drinking, cigarette smoking, diet, exercise, and reproductive and medical histories. The response rate was 92%. From 1993 to 2000, 161 men and 134 women were diagnosed with colorectal cancer at two major hospitals in the city. Relative risks and 95% confidence intervals were calculated by using Cox proportional hazard models. A positive relation between height and colorectal cancer was seen in both sexes, controlling for age, body mass index (BMI), smoking and drinking habits, and years of education. The findings were statistically significant only for men (relative risk 2.13 for the tallest compared with the shortest height tertile; 95% confidence interval=1.26-3.58). Body mass index was also associated positively with colon cancer risk for men, whereas the pattern for women was not clear. There was a positive association between pack-years of cigarette smoking and the risk of rectal cancer in men. A positive dose-response relation between alcohol consumption and colon cancer risk was observed for men and women.

Primary prevention of colorectal cancer: diet and drugs

Primary prevention of colonic adenomas and cancer through dietary interventions or chemoprevention has great appeal. This article discusses primary prevention goals and promising nutritional or chemopreventive strategies. There is substantial observational evidence that diets high in total calories and fat and or low in fruits and vegetables or total fiber as well as low levels of physical activity are related to the risk of colonic neoplasia. Similar observational data indicate that diets high in specific nutrients such as antioxidant vitamins or calcium may be protective. The article describes some of the newer chemopreventive agents and reviews the data linking diet and lifestyle to colorectal cancer risk, focusing on interventions that have also been studied in prospective clinical trials. Finally the evidence supporting the role of non-steroidal anti-inflammatory drugs for the chemoprevention of CRC is reviewed and the status of several other promising newer agents that are entering human trials is summarized.

Childhood growth and adult cancer

Associations between different patterns of childhood growth and later adult health have recently received much attention. Most studies have found higher mortality in shorter people, explained by their higher incidence of cardiorespiratory disease. In this chapter, associations of cancer with markers of growth at different developmental phases - infancy, childhood and puberty - and with final adult height are reviewed. The relationship between birthweight and cancer is generally positive, with the greatest risk among high-birthweight babies. Childhood and adult tallness are related to higher cancer risk. This is particularly evident for cancers of the breast, prostate, colo-rectum, haematopoietic system and endometrium. Leg length may be more strongly associated than trunk length with cancer risk. Possible explanations for these findings are discussed in relation to nutritional intake and hormonal levels.

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 prevalence and trends in Latin-American countries

The prevalence of obesity in some lower-income and transitional countries is as high as, or even higher than, the prevalence reported in developed nations, and it seems to be increasing rapidly. In most countries, the prevalence of obesity is higher in women than in men, and higher in urban than in rural areas. Preobesity prevalence is very high in most Latin-American countries. Sixty per cent of the population in Venado Tuerto (Argentina) has a body mass index (BMI) of > or = 25 kg m-2, as do 35% of the population in Brazil, 60% in Mexico, 68% in Paraguay and 53% in Peru. Trends are available from Brazil, where marked increases in the prevalence of obesity have occurred, except in women from higher-income groups. Women from the higher-income quartiles in urban regions experienced a marked reduction in obesity prevalence from 1989 to 1997 (12.8 to 9.2%). Although data in children is scant, the prevalence of undernutrition is decreasing and the prevalence of obesity is high also in Latin-American children. The prevalence of obesity is high even in minority Indian groups. Rapid changes in dietary structure (in particular associated with urbanization) and major changes in the levels of physical activity, both occupationally and during leisure time, may explain these changes.