Recent theories propose that a Western lifestyle may increase cancer risk through alterations in the metabolism of insulin and insulin-like growth factors (IGF: McKeown-Eyssen, 1994; Giovannucci, ...1995; Kaaks, 19%; Werner & LeRoith, 1996). Insulin regulates energy metabolism, and increases the bioactivity of IGF-I, by enhancing its synthesis. and by decreasing several of its binding proteins (IGFBP; IGFBP-1 and -2). Insulin and IGF-I both stimulate anabolic processes as a function of available energy and elementary substrates (e.g. amino acids). The anabolic signals by insulin or IGF-I can promote tumour development by inhibiting apoptosis, and by stimulating cell proliferation. Furthermore, both insulin and IGF-I stimulate the synthesis of sex steroids, and inhibit the synthesis of sex hormone-binding globulin (SFIBG), a binding protein that regulates the bioavailability of circulating sex steroids to tissues. The present paper reviews epidemiological findings relating the risk of cancers of the colo-rectum, pancreas, breast, endometrium and prostate to body size (obesity, height) and physical activity, and discusses the relationships between obesity and physical activity and plasma levels of insulin, IGF-I and IGFBP. Subsequent sections review epidemiological findings relating cancer risk to indices of chronic hyperinsulinaemia, and to plasma levels of IGF-I and IGFBP. Conclusions are that chronic hyperinsulinaemia may be a cause of cancers of the colon, pancreas and endometrium, and also possibly of the breast. On the other hand, elevated plasma IGF-I, as total concentrations or relative to levels of IGFBP-3, appears to be related to an increased risk of prostate cancer, breast cancer in young women, and possibly cob-rectal cancer. For cancers of the endometrium, breast and prostate, these findings are discussed in the context of relationships between insulin and IGF-I and levels of bioavailable sex steroids.
To examine whether pregnancy loss (miscarriage, abortion or stillbirth) is associated with a higher risk of myocardial infarction (MI) and stroke.
Population-based prospective cohort study.
The ...European Prospective Investigation into Cancer and Nutrition (EPIC) cohort in Heidelberg, Germany (mean follow-up 10.8 years).
All 11,518 women who had ever been pregnant (aged 35-66).
Out of the participants, 2876 (25%) had at least one miscarriage, 2053 (18%) had at least one abortion and 209 (2%) had at least one stillbirth. During the follow-up, 82 cases of MI and 112 of stroke (confirmed by medical records) occurred in these women. Each stillbirth increased the risk of MI 2.65 times (95% CI for age-adjusted HR 1.37 to 5.12; HR adjusted for age, smoking, alcohol consumption, body mass index, waist to hip ratio, physical activity, education, number of pregnancies, hypertension, hyperlipidaemia and diabetes mellitus: HR 2.32 95% CI 1.19 to 4.50, 95% CI). Recurrent miscarriage (>3) was associated with about nine times higher risk of MI (age-adjusted HR = 8.90, 95% CI 3.18 to 24.90; fully adjusted HR 5.06, 95% CI 1.26 to 20.29). No significant association was found between abortion and MI or between any type of pregnancy loss and stroke.
These results suggest that women who experience spontaneous pregnancy loss are at a substantially higher risk of MI later in life. Recurrent miscarriage and stillbirth are strong sex-specific predictors for MI and thus should be considered as important indicators for cardiovascular risk factors monitoring and preventive measures. Further research is suggested to elucidate underlying risk factors of pregnancy loss that at the same time strongly predispose to cardiovascular disease.
Summary Background Associations between circulating concentrations of oestrogens, progesterone, and androgens with breast cancer and related risk factors in premenopausal women are not well ...understood. We aimed to characterise these associations with a pooled analysis of data from seven studies. Methods Individual participant data for prediagnostic sex hormone and sex hormone-binding globulin (SHBG) concentrations were contributed from seven prospective studies. We restricted analyses to women who were premenopausal and younger than 50 years at blood collection, and to women with breast cancer diagnosed before age 50 years. We estimated odds ratios (ORs) with 95% CIs for breast cancer associated with hormone concentrations by conditional logistic regression in cases and controls matched for age, date of blood collection, and day of cycle, with stratification by study and further adjustment for cycle phase. We examined associations of hormones with risk factors for breast cancer in control women by comparing geometric mean hormone concentrations in categories of these risk factors, adjusted for study, age, phase of menstrual cycle, and body-mass index (BMI). All statistical tests were two-sided. Findings We included data for up to 767 women with breast cancer and 1699 controls in the risk analyses. Breast cancer risk was associated with a doubling in concentrations of oestradiol (OR 1·19, 95% CI 1·06–1·35), calculated free oestradiol (1·17, 1·03–1·33), oestrone (1·27, 1·05–1·54), androstenedione (1·30, 1·10–1·55), dehydroepiandrosterone sulphate (1·17, 1·04–1·32), testosterone (1·18, 1·03–1·35), and calculated free testosterone (1·08, 0·97–1·21). Breast cancer risk was not associated with luteal phase progesterone (doubling in concentration OR 1·00, 95% CI 0·92–1·09), and adjustment for other factors had little effect on any of these ORs. Cross-sectional analyses in control women showed several associations of sex hormones with breast cancer risk factors. Interpretation Circulating oestrogens and androgens are positively associated with the risk for breast cancer in premenopausal women. Funding Cancer Research UK.
Breast cancer incidence rates are high in societies with a Western lifestyle characterized by low levels of physical activity, and by an energy-dense diet rich in total and saturated fat and refined ...carbohydrates. Epidemiologic studies, so far mostly on postmenopausal women, have shown that breast cancer risk is increased in hyperandrogenic women, with decreased levels of plasma sex-hormone binding globulin, and with increased levels of testosterone and of free estrogens. This paper describes the role of hyperinsulinemia as a physiologic link between nutritional lifestyle factors, obesity, and the development of a hyperandrogenic endocrine profile, and reviews evidence that may or may not support the theory that chronic hyperinsulinemia is an underlying cause of breast cancer. An hypothesis is presented, stipulating that breast cancer risk is increased not only in hyperandrogenic postmenopausal women, but also in premenopausal women with mild hyperandrogenism and normal (ovulatory) menstrual cycles. The author suggests further investigation as to whether there is a positive association between risk of breast cancer before menopause and subclinical forms of the polycystic ovary syndrome (PCOS), and to what extent diet and physical activity during childhood, by modulating the degree of insulin resistance during adolescence, may or may not be determinants of a PCO-like hyperandrogenic endocrine profile persisting into adulthood.
Summary
Background
There are plausible mechanisms for how dietary docosahexaenoic acid (DHA), an n−3 polyunsaturated fatty acid, could prevent Crohn's disease (CD).
Aim
To conduct a prospective study ...to investigate the association between increased intake of DHA and risk of CD.
Methods
Overall, 229 702 participants were recruited from nine European centres between 1991 and 1998. At recruitment, dietary intakes of DHA and fatty acids were measured using validated food frequency questionnaires. The cohort was monitored through to June 2004 to identify participants who developed incident CD. In a nested case–control analysis, each case was matched with four controls; odds ratios (ORs) were calculated for quintiles of DHA intake, adjusted for total energy intake, smoking, other dietary fatty acids, dietary vitamin D and body mass index.
Results
Seventy‐three participants developed incident CD. All higher quintiles of DHA intake were inversely associated with development of CD; the highest quintile had the greatest effect size (OR = 0.07; 95% CI = 0.02–0.81). The OR trend across quintiles of DHA was 0.54 (95% CI = 0.30–0.99, Ptrend = 0.04). Including BMI in the multivariate analysis, due to its correlation with dietary fat showed similar associations. There were no associations with the other dietary fatty acids studied.
Conclusion
There were inverse associations, with a biological gradient between increasing dietary docosahexaenoic acid intakes and incident Crohn's disease. Further studies in other populations should measure docosahexaenoic acid to determine if the association is consistent and the hypothesis tested in randomised controlled trials of purely docosahexaenoic acid supplementation.
To examine the relation of well-known factors of the metabolic syndrome (MetS) as well as related circulating factors, with risk of colorectal cancer.
We performed a case control study of 306 ...colorectal cancer cases and 595 matched controls nested in the Northern Sweden Health and Disease Cohort. Levels of C-peptide, glycated haemoglobin (HbA1c), leptin and adiponectin were measured in cryopreserved samples. Body mass index (BMI), systolic and diastolic blood pressure and fasting and post-load plasma glucose, had been measured in a subcohort. Conditional logistic regression was used to calculate odds ratios (OR) of disease, including risk assessments for the MetS factors: obesity (BMI>30 kg m(-2)), hypertension (blood pressure > or =140/90 mmHg or use of anti-hypertensive drugs) and hyperglycaemia (fasting glucose > or =6.1 mmol l(-1) or post-load glucose in capillary plasma > or =8.9 mmol l(-1)).
None of the studied variables were significantly associated with risk across quartiles. Presence of obesity, hypertension and hyperglycaemia significantly increased the risk of colorectal cancer; OR for three vs null factors was 2.57 (95% Confidence Interval CI 1.20-5.52; P (trend)=0.0021), as compared to a 30 to 70% increased risk for the factors in single. Similarly, top decile levels of C-peptide, HbA1c and leptin/adiponectin ratio were associated with an increased risk; ORs for top vs deciles 1-9 were 1.56 (95% CI 0.93-2.62; P=0.090), 1.83 (95% CI 1.00-3.36; P=0.051) and 1.50 (95% CI 0.83-2.71; P=0.18), respectively.
Our study support the view that components of the MetS increase risk of colorectal cancer, and further suggests that only very high levels of metabolic factors confer an increased risk.
Background: Leading a Western lifestyle, being overweight, and being sedentary are associated with an increased risk of colorectal cancer. Recent theories propose that the effects of these risk ...factors may be mediated by increases in circulating insulin levels and in the bioactivity of insulin-like growth factor (IGF)-I. To test this hypothesis, we conducted a case–control study nested within a cohort of 14 275 women in New York. Methods: We used blood samples that had been obtained from these women from March 1985 through June 1991 and stored in a biorepository. C-peptide (a marker for insulin secretion), IGF-I, and IGF-binding proteins (IGFBPs)-1, -2, and -3 were assayed in the serum of 102 women who subsequently developed colorectal cancer and 200 matched control subjects. Logistic regression was used to relate cancer risk to these peptide levels, by adjustment for other risk factors. All statistical tests used are two-sided. Results: Colorectal cancer risk increased with increasing levels of C-peptide (Ptrend = .001), up to an odds ratio (OR) of 2.92 (95% confidence interval CI = 1.26–6.75) for the highest versus the lowest quintiles, after adjustment for smoking. For colon cancer alone (75 case subjects and 146 control subjects), ORs increased up to 3.96 (95% CI = 1.49–10.50; Ptrend <.001) for the highest versus the lowest quintiles. A statistically significant decrease in colorectal cancer risk was observed for increasing levels of IGFBP-1 (Ptrend = .02; OR in the upper quintile = 0.48 95% CI = 0.23–1.00), as well as for the highest quintile of IGFBP-2 levels (Ptrend = .06; OR = 0.38 95% CI = 0.15–0.94). Colorectal cancer risk showed a modest but statistically nonsignificant positive association with levels of IGF-I and was statistically significantly increased for the highest quintile of IGFBP-3 (OR = 2.46 95% CI = 1.09–5.57). Conclusions: Chronically high levels of circulating insulin and IGFs associated with a Western lifestyle may increase colorectal cancer risk, possibly by decreasing IGFBP-1 and increasing the bioactivity of IGF-I.
Abstract
Background and Aims
Population-based prospective cohort studies investigating fibre intake and development of inflammatory bowel disease are lacking. Our aim was to investigate the ...association between fibre intake and the development of Crohn’s disease CD and ulcerative colitis UC in a large European population.
Methods
In total, 401326 participants, aged 20–80 years, were recruited in eight countries in Europe between 1991 and 1998. At baseline, fibre intake total fibres, fibres from fruit, vegetables and cereals was recorded using food frequency questionnaires. The cohort was monitored for the development of inflammatory bowel disease. Each case was matched with four controls and odds ratios ORs for the exposures were calculated using conditional logistic regression. Sensitivity analyses according to smoking status were computed.
Results
In total, 104 and 221 participants developed incident CD and UC, respectively. For both CD and UC, there were no statistically significant associations with either quartiles, or trends across quartiles, for total fibre or any of the individual sources. The associations were not affected by adjusting for smoking and energy intake. Stratification according to smoking status showed null findings apart from an inverse association with cereal fibre and CD in non-smokers Quartile 4 vs 1 OR = 0.12, 95% confidence interval = 0.02–0.75, p = 0.023, OR trend across quartiles = 0.50, 95% confidence interval = 0.29–0.86, p = 0.017.
Conclusion
The results do not support the hypothesis that dietary fibre is involved in the aetiology of UC, although future work should investigate whether there may be a protective effect of specific types of fibre according to smoking status in CD.
Background: A moderate association exists between body mass index (BMI) and colorectal cancer. Less is known about the effect of weight change.Objective: We investigated the relation between BMI and ...weight change and subsequent colon and rectal cancer risk.Design: This was studied among 328,781 participants in the prospective European Prospective Investigation into Cancer–Physical Activity, Nutrition, Alcohol, Cessation of Smoking, Eating study (mean age: 50 y). Body weight was assessed at recruitment and on average 5 y later. Self-reported weight change (kg/y) was categorized in sex-specific quintiles, with quintiles 2 and 3 combined as the reference category (men: −0.6 to 0.3 kg/y; women: −0.4 to 0.4 kg/y). In the subsequent years, participants were followed for the occurrence of colon and rectal cancer (median period: 6.8 y). Multivariable Cox proportional hazards regression analyses were used to study the association.Results: A total of 1261 incident colon cancer and 747 rectal cancer cases were identified. BMI at recruitment was statistically significantly associated with colon cancer risk in men (HR: 1.04; 95% CI: 1.02, 1.07). Moderate weight gain (quintile 4) in men increased risk further (HR: 1.32; 95% CI: 1.04, 1.68), but this relation did not show a clear trend. In women, BMI or weight gain was not related to subsequent risk of colon cancer. No statistically significant associations for weight loss and colon cancer or for BMI and weight changes and rectal cancer were found.Conclusions: BMI attained at adulthood was associated with colon cancer risk. Subsequent weight gain or loss was not related to colon or rectal cancer risk in men or women.
PDF
