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

Diet and cancer

The large differences in cancer rates among countries, striking changes in these rates among migrating populations, and rapid changes over time within countries indicate that some aspect of lifestyle or environment is largely responsible for the common cancers in Western countries. Dietary fat has been hypothesized to be the key factor because national consumption is correlated with the international differences. However, detailed analyses in large prospective studies have not supported an important role of dietary fat. Instead, positive energy balance, reflected in early age at menarche and weight gain as an adult, is an important determinant of breast and colon cancers, consistent with numerous studies in animals. As a contributor to positive energy balance, and possibly by other mechanisms, physical inactivity has also been shown to be a risk factor for these diseases and in part accounts for the international differences. Although the percentage of calories from fat in the diet does not appear related to risk of colon cancer, greater risks have been seen with higher consumption of red meat, suggesting that factors other than fat per se are important. In many case-control studies, a high consumption of fruits and vegetables has been associated with reduced risks of numerous cancers, but recent prospective studies suggest these associations may have been overstated. Among the factors in fruits and vegetables that have been examined in relation to cancer risk, present data most strongly support a benefit of higher folic acid consumption in reducing risks of colon and breast cancers. These findings have been bolstered by an association between incidence of colon cancer and a polymorphism in the gene for methylenetetrahydrofolate reductase, an enzyme involved in folic acid metabolism. The benefits of folic acid appear strongest among persons who regularly consume alcohol, which itself is associated with risk of these cancers. Numerous other aspects of diet are hypothesized to influence the risks of cancers in Western countries, but for the moment the evidence is unclear.

Are alcohol intake and smoking associated with mycosis fungoides? A European multicentre case-control study

The incidence of mycosis fungoides (MF) is low, and the aetiology of the disease is unknown. The aim of this study was to investigate whether wine consumption protects against the disease and whether smoking constitutes a risk factor. This paper is part of the European Rare Cancers Study that tries to determine the risk factors for seven selective rare cancers, including mycosis fungoides, involved in the development of cancer. A multicentre case-control study was conducted in six European countries. Only incident cases with confirmed histology were included in the analysis which include a total of 76 cases of MF and 2899 controls. Wine intake had no protective effect; on the contrary the consumption of more than 24 g of alcohol per day was associated with a high risk of MF (odds ratio (OR)=3.02, 95% confidence interval (CI), 1.34-6.79), after adjusting for centre, country, age, sex and education. There was a dose-dependent increase in the risk of MF with increased smoking habits, albeit the observed trend was not statistically significant. A combined exposure to high tobacco and alcohol use yielded a significantly increased risk factor for MF (P=0.0073). Alcohol intake was associated with MF.

High-risk colorectal adenomas and serum insulin-like growth factors

BACKGROUND

This study investigated the hypothesis that circulating levels of insulin-like growth factor (IGF) I and its main binding protein (IGFBP-3) predict for the presence of colorectal adenomas, surrogate markers of colorectal cancer risk.

METHODS

Within the Flexi-Scope Trial (healthy volunteers aged 55-64 years), at one study centre, IGF-I and IGFBP-3 levels in serum samples collected prospectively from 442 attendants were measured. Of these, 100 individuals underwent a complete screening colonoscopy. There were 47 normal examinations, while in 11 examinations low-risk adenomas and in 42 examinations high-risk adenomas were identified. Estimates of relative risk (RR) for the adenomatous stages were calculated by means of unconditional logistic regression, adjusting for known risk factors.

RESULTS

Mean serum IGF-I and IGFBP-3 levels were similar in individuals with a normal colonoscopy finding and in those with low-risk adenomas. By contrast, the mean(s.d.) serum IGF-I level was increased (190(53) versus 169(54) microg/l; P = 0.06) and the serum IGFBP-3 concentration was significantly decreased (3.22(0.60) versus 3.47(0.62) mg/l; P = 0.05) in individuals with high-risk adenomas compared with levels in those with normal colonoscopy and low-risk adenomas combined. Levels were unaffected by removal of the adenomas. With high-risk adenoma as the dependent factor, regression models demonstrated a significant positive association with IGF-I after controlling for IGFBP-3 (RR per one standard deviation (1s.d.) change 4.39 (95 per cent confidence interval (c.i.) 1.31-14.7); P = 0.02) and, independently, an inverse association with IGFBP-3 after adjustment for IGF-I (RR per 1s.d. change 0.41 (95 per cent c.i. 0. 20-0.82); P = 0.01).

CONCLUSION

These findings suggest that circulating IGF-I and IGFBP-3 levels are related to future colorectal cancer risk and, specifically, may predict adenoma progression.

Predictors of weight gain: the biological-behavioural debate

The rapidly increasing prevalence of obesity, in spite of an unchanged gene pool, makes it interesting to search for biological factors which increase the susceptibility at the individual level as well as searching for the responsible environmental factors. Among the identified metabolic factors is a low resting metabolic rate for given body size and composition, a high respiratory quotient (RQ) indicating a low fat oxidation and a low spontaneous physical activity, all factors which are regarded as being under substantial genetic influence. Among the environmental factors, it is low levels of physical activity, increasing inactivity and a high fat diet that are probably the most important ones. In this review we have focused on controversies in this area. Understanding the interaction between the constitutional biological factors and the environmentally determined lifestyle factors it is important to produce better options for both the prevention and treatment of obesity.

Colorectal cancer: molecules and populations

The epidemiology and molecular biology of colorectal cancer are reviewed with a view to understanding their interrelationship. Risk factors for colorectal neoplasia include a positive family history, meat consumption, smoking, and alcohol consumption. Important inverse associations exist with vegetables, nonsteroidal anti-inflammatory drugs (NSAIDs), hormone replacement therapy, and physical activity. There are several molecular pathways to colorectal cancer, especially the APC (adenomatous polyposis coli)-beta-catenin-Tcf (T-cell factor; a transcriptional activator) pathway and the pathway involving abnormalities of DNA mismatch repair. These are important, both in inherited syndromes (familial adenomatous polyposis [FAP] and hereditary nonpolyposis colorectal cancer [HNPCC], respectively) and in sporadic cancers. Other less well defined pathways exist. Expression of key genes in any of these pathways may be lost by inherited or acquired mutation or by hypermethylation. The roles of several of the environmental exposures in the molecular pathways either are established (e.g., inhibition of cyclooxygenase-2 by NSAIDs) or are suggested (e.g., meat and tobacco smoke as sources of specific blood-borne carcinogens; vegetables as a source of folate, antioxidants, and inducers of detoxifying enzymes). The roles of other factors (e.g., physical activity) remain obscure even when the epidemiology is quite consistent. There is also evidence that some metabolic pathways, e.g., those involving folate and heterocyclic amines, may be modified by polymorphisms in relevant genes, e.g., MTHFR (methylenetetrahydrofolate reductase) and NAT1 (N-acetyltransferase 1) and NAT2. There is at least some evidence that the general host metabolic state can provide a milieu that enhances or reduces the likelihood of cancer progression. Understanding the roles of environmental exposures and host susceptibilities in molecular pathways has implications for screening, treatment, surveillance, and prevention.

Associations between physical activity and susceptibility to cancer: possible mechanisms

Physical activity is associated with a reduced risk of all-cause and colonic cancers, and it seems to exert a weaker effect on the risk of breast, lung and reproductive tract tumours. This review examines possible mechanisms behind the observed associations. Restriction of physical activity by pre-existing disease may contribute to the association with lung cancers, but seems a less likely explanation for other types of tumour. Indirect associations through activity-related differences in body build or susceptibility to trauma seem of minor importance. Potential dietary influences include overall energy balance and energy expenditure, the intake and/or bioavailability of minerals, antioxidant vitamins and fibre, and the relative proportions of protein and fat ingested. Links between regular exercise and other facets of lifestyle that influence cancer risks are not very strong, although endurance athletes are not usually smokers, and regular leisure activity is associated with a high socioeconomic status which tends to reduce exposure to airborne carcinogens, both at work and at home. Overall susceptibility to cancer shows a 'U'-shaped relationship to body mass index (mass/height2) reflecting, in part, the adverse influences of cigarette smoking and a tall body build for those with low body mass indices and, in part, the adverse effect of obesity at the opposite end of the body mass index distribution. Obesity seems a major component in the exercise-cancer relationship, with a particular influence on reproductive tract tumours; it alters the pathways of estradiol metabolism, decreases estradiol binding and facilitates the synthesis of estrogens. Among the hormonal influences on cancer risk, insulin-like growth factors promote tumour development and exercise-mediated increases in cortisol and prostaglandin levels may depress cellular components of immune function. However, the most important change is probably the suppression of the gonadotropic axis. Apparent gender differences in the benefits associated with regular exercise reflect gender differences in the hormonal milieu and also a failure to adapt activity questionnaires to traditional patterns of physical activity in females. The immune system is active at various stages of tumour initiation, growth and metastasis. However, acute and chronic changes in immune response induced by moderate exercise are rather small, and their practical importance remains debatable. At present, the oncologist is confronted by a plethora of interesting hypotheses, and further research is needed to decide which are of practical importance.

Leisure-time physical activity, body size, and colon cancer in women. Nurses' Health Study Research Group

BACKGROUND

Physical inactivity and high body mass index (weight in kilograms divided by height in square meters) have been linked to increased risk of colon cancer. However, none of the few prospective studies in women has shown a statistically significant reduction in colon cancer incidence or mortality associated with increased leisure-time physical activity.

PURPOSE

In this prospective study, we asked whether leisure-time physical activity, body mass index, or body fat distribution could significantly influence the risk of colon cancer in women.

METHODS

The participants in this study were enrolled in the Nurses' Health Study, which began in 1976. Every 2 years, the women provided additional personal information and information on medical risk factors and major medical events. The time spent per week at a variety of leisure-time physical activities was determined, and the time spent at each activity was multiplied by its typical energy expenditure, expressed in terms of metabolic equivalents or METs. The resulting values for each woman were added to yield an MET-hours-per-week score. Reported diagnoses of colon cancer were confirmed by review of hospital records and pathology reports. Relative risks and associated 95% confidence intervals were calculated.

RESULTS

In multivariate analyses that included body mass index, women who expended more than 21 MET-hours per week on leisure-time physical activity had a relative risk of colon cancer of 0.54 (95% confidence interval [CI] = 0.33-0.90) in comparison with women who expended less than 2 MET-hours per week. Women who had a body mass index greater than 29 kg/m2 had a relative risk of colon cancer of 1.45 (95% CI = 1.02-2.07) in comparison with women who had a body mass index less than 21 kg/m2. A tendency toward higher colon cancer risk was observed for increasing waist-to-hip ratio (relative risk = 1.48 [95% CI = 0.88-2.49] for comparison of the highest quintile ratio [>0.833] to the lowest [<0.728]).

CONCLUSIONS AND IMPLICATIONS

The significant inverse association between leisure-time physical activity and incidence of colon cancer in women in this study is consistent with what has been found in men. Recommendations to increase physical activity and maintain lean body weight should receive greater emphasis as part of a feasible approach to the prevention of colon cancer.

The Nurses' Health Study: 20-year contribution to the understanding of health among women

The Nurses' Health Study was designed as a prospective follow-up study to examine relations between contraception and breast cancer. With follow-up questionnaires mailed every 2 years, investigators have added extensive details of lifestyle practices. The study, currently in its 20th year, has maintained high follow-up with > 90% of participants responding to each of the follow-up cycles since 1988. The relations between use of hormones, diet, exercise, and other lifestyle practices have been related to the development of a wide range of chronic illnesses among women. This review describes the methods used to follow up the study participants and summarizes the major findings that have been described over the first 20 years of the study. We highlight additional areas added to the study in recent years to address emerging issues in women's health. Special emphasis is placed on the recent findings from the study, including relations between weight gain and heart disease, diabetes, and mortality, the lack of relation between calcium and osteoporotic fractures, and the positive relation between postmenopausal use of hormones and risk of breast cancer.

The relationship between smoking exposure and p53 overexpression in colorectal cancer

Although epidemiological studies of the relationship between cigarette smoking and colorectal cancer risk have been equivocal, a positive association is consistently found for colorectal adenoma development. We performed an epidemiological study to determine whether p53 protein overexpression, in tumours obtained at the time of resection, is associated with cigarette exposure in colorectal cancer. A total of 163 colorectal cancer cases and 326 healthy controls responded to a standardised questionnaire on colorectal cancer risk factors including detailed information on their history of cigarette smoking. All patients' tumours were analysed immunohistochemically for p53 overexpression using an avidin-biotin immunoperoxidase procedure and polyclonal anti-p53 antibody CM1. Comparison of colorectal cases with controls revealed an elevated risk for ex-smokers (OR = 1.34, 95% CI 0.85-2.12) and current smokers (OR = 1.13, 95% CI 0.63-2.02) when compared with non-smokers. No dose-response relationship was found for total pack-years of smoking (trend test: P = 0.19). However, a trend for total pack-years of smoking was found when p53-positive cases were compared with p53-negative cases suggesting aetiological, heterogeneity (trend test: P = 0.06). Estimating the individual relative risk of developing a p53-positive tumour relative to controls showed no associations for smoking status or total pack-years of smoking. However, when p53-negative cases were compared with controls, an elevated risk was found for ex-smokers (OR = 1.84, 95% CI 1.00-3.37) and current years of smoking (trend test: P = 0.03). Colorectal tumours developing through p53-positive dependent pathways were not associated with smoking exposure. A significant increase in risk was observed for the p53-negative independent pathway with smoking. p53 overexpression appears to be associated with smoking exposure in colorectal cancer.

Physical activity, obesity, and risk of colorectal adenoma in women (United States)

The relationship between physical inactivity, body mass index (BMI) (wt[kg]/ht[m]2), and pattern of adipose distribution with risk of colorectal adenomas (precursors of cancer) was examined in 13,057 female nurses in the United States, 40 to 65 years of age in 1986, who had an endoscopy between 1986 and 1992. From 1986 to 1992, 439 participants were newly diagnosed with adenomas of the distal colorectum. After controlling for age, prior endoscopy, parental history of colorectal cancer, smoking, aspirin, and intakes of animal fat, dietary fiber, folate, methionine, and alcohol, physical activity was associated inversely with risk of large (> or = 1 cm) adenomas in the distal colon (relative risk [RR] = 0.57, 95 percent confidence interval [CI] = 0.30-1.08, comparing high and low quintiles of average weekly energy expenditure from leisure-time activities; P trend = 0.05). Much of the benefit came from activities of moderate intensity such as brisk walking. In addition, BMI was associated directly with risk of large adenomas in the distal colon (multivariate RR = 2.21 [CI = 1.18-4.16], P trend = 0.0001, for BMI > or = 29 cf < 21 kg/m2). Waist circumference and the waist-to-hip ratio (WHR) were not related significantly to adenoma independently of BMI, but women with both a high BMI and high WHR were at greater risk of large colon adenoma (multivariate RR = 1.99, CI = 0.98-4.05) than women with high BMI but relatively low WHR (multivariate RR = 1.35, CI = 0.61-2.97). BMI was not related to small (< 1 cm) adenoma risk but physical activity had an inverse association with small adenomas in the distal colon (multivariate RR = 0.68, CI = 0.40-1.15, P trend = 0.03). The relationships between BMI or physical activity were considerably weaker and inconsistent for rectal adenomas. These results, in women, support an inverse association between physical activity and occurrence or progression of adenomas in the distal colon; obesity is associated with an elevated risk of large adenomas.

Insulin and colon cancer

Some factors related to Westernization or industrialization increase risk of colon cancer. It is believed widely that this increase in risk is related to the direct effects of dietary fat and fiber in the colonic lumen. However, the fat and fiber hypotheses, at least as originally formulated, do not explain adequately many emerging findings from recent epidemiologic studies. An alternative hypothesis, that hyperinsulinemia promotes colon carcinogenesis, is presented here. Insulin is an important growth factor of colonic epithelial cells and is a mitogen of tumor cell growth in vitro. Epidemiologic evidence supporting the insulin/colon-cancer hypothesis is largely indirect and based on the similarity of factors which produce elevated insulin levels with those related to colon cancer risk. Specifically, obesity--particularly central obesity, physical inactivity, and possibly a low dietary polyunsaturated fat to saturated fat ratio--are major determinants of insulin resistance and hyperinsulinemia, and appear related to colon cancer risk. Moreover, a diet high in refined carbohydrates and low in water-soluble fiber, which is associated with an increased risk of colon cancer, causes rapid intestinal absorption of glucose into the blood leading to postprandial hyperinsulinemia. The combination of insulin resistance and high glycemic load produces particularly high insulin levels. Thus, hyperinsulinemia may explain why obesity, physical inactivity, and a diet low in fruits and vegetables and high in red meat and extensively processed foods, all common in the West, increase colon cancer risk.

The association of body size and large bowel cancer risk in Wisconsin (United States) women

Body size is associated with the risk of many diseases, including diabetes, heart disease, and some cancers. To evaluate the association of body size with large bowel cancer, height and weight measurements were ascertained by telephone interview from 779 Wisconsin (United States) women with newly reported diagnoses of carcinoma of the colon and rectum. Controls (n = 2,315) interviewed for this case-control study were selected randomly from Wisconsin driver's license files and Health Care Financing Administration files. The effects of weight and height were examined using multiple logistic regression to control for potential confounding variables. In this study, weight adjusted for height increased the risk of colon cancer (odds ratio [OR] for 72.57-148.33 kg cf 36.29-58.05 kg = 1.4, 95 percent confidence interval [CI] = 1.0-1.9) but did not increase the risk of rectal cancer. Height did not influence risk for cancer of either the colon or the rectum. Left-colon subsite analysis showed especially strong associations with current weight and with percent change in weight since age 18. These data suggest that a dose-response relationship exists between body size and risk of colon cancer in women; body size did not appear to influence risk of rectal cancer.

Increased risk of colorectal cancer among smokers: results of a 26-year follow-up of US veterans and a review

To clarify the relationship between tobacco use and risk of colorectal cancer, we evaluated a cohort of 248,046 American veterans followed prospectively for 26 years. In comparison with veterans who had never used tobacco, the risk of death was significantly increased for colon cancer and rectal cancer among current and former cigarette smokers and among pipe or cigar smokers, controlling for social class and occupational physical activity. Rectal-cancer risk was also significantly elevated among users of chewing tobacco or snuff. For both sites, risk increased significantly with pack-years, earlier age at first use, and number of cigarettes. These results reinforce 2 recent reports of the association of cigarette smoking and colorectal cancer in men and women. Inconsistencies in the findings of earlier epidemiologic studies appear to be due in large part to differences in length of follow-up or in choice of controls. Studies with at least 20 years of follow-up or population-based controls have tended to find elevated risk with tobacco smoking, while those with shorter follow-up or hospital controls have not. This, plus the strength and consistency of the association of smoking and colon polyps, suggest that smoking may primarily affect an early stage in the development of colon cancer. If this association is causal, tobacco use may be responsible for 16% of colon-cancer and 22% of rectal-cancer deaths among these veterans.

Cutaneous malignant melanoma: association with height, weight and body-surface area. a prospective study in Norway

To investigate whether anthropometric indices as body height, body-mass index (BMI) and body-surface area (BSA) have any influence on the risk of cutaneous malignant melanoma (CMM), we analyzed height and weight data from a Norwegian screening survey running between 1963 and 1975 and comprising 1.3 million individuals followed for 14 to 26 years. Among females, CMM was diagnosed in 2814 incident cases, while the number among males was 2144 during 22,988,345 person-years of follow-up. With adjustment for age, birth cohort, geographic region and BMI, the risk for CMM increased significantly with increasing quintiles of height in both sexes. The tallest persons were at greater relative risk than the shortest ones: 1.60 and 1.59 in males and females respectively. This positive association was also found for CMM localized on face and trunk in both sexes, and in the lower limbs only in females. Males in the highest quintile of BMI had a relative risk for CMM of 1.26 compared with the lowest quintile, while a non-significant negative association were found in obese females. This negative association increased and was significant for CMM located on the trunk and lower limbs in females. Among males we observed a consistent association between BSA and risk of CMM similar to that for height. These relationships between anthropometric indices and CMM are discussed according to factors which promote growth, among which nutrition, social class and hormones are the most important.

A meta-analysis of cholecystectomy and risk of colorectal cancer

BACKGROUND

Over 60 studies have addressed the hypothesis that the risk of colorectal cancer is increased following cholecystectomy; these studies have yielded inconsistent findings. The aim of the present study was to quantitatively summarize the results from the collective studies.

METHODS

A meta-analysis of the published studies addressing the relation between cholecystectomy and colorectal cancer was conducted.

RESULTS

The combined results from 33 case-control studies showed an association between cholecystectomy and risk of colorectal cancer (pooled relative risk [RR] = 1.34; 95% confidence interval [CI] = 1.14-1.57), particularly when limited to the proximal colon (RR = 1.88; 95% CI = 1.54-2.30). In most studies, the risk was stronger when the first 5-15 years following the surgery were excluded. The results from 6 cohort studies, with follow-up to approximately 15 years postcholecystectomy, were generally null (RR = 0.97; 95% CI = 0.82-1.14). A more limited body of evidence suggests that cholelithiasis is related to an elevated risk of proximal colon cancer.

CONCLUSIONS

Because the risks varied substantially by study design and because time since cholecystectomy or potentially confounding factors were often not considered, we could not firmly quantitate this risk. However, the findings are consistent with other evidence that suggests some characteristic of bile acid metabolism increases the risk of cancer of the proximal colon.

Obesity in youth and middle age and risk of colorectal cancer in men

To investigate an association between colon cancer and obesity during early adulthood--a potentially important period in the etiology of this disease--the authors assembled, by computer linkage, a population-based historical cohort of 52,539 men born between 1913 and 1927 residing in Hawaii (USA), for whom weight and height had been recorded in 1942-43 and 1972. Linkage of this cohort to the Hawaii Tumor Registry resulted in the identification of 737 incident cases of colorectal cancer for 1972-86. An average of 3.8 cancer-free controls were matched to each case on month and year of birth and ethnicity of the parents. A case-control analysis in each anatomic subsite of the large bowel revealed that both early and middle-age body mass increased the risk of sigmoid cancer in men in a dose-dependent fashion. The odds ratios (OR) for sigmoid cancer for the highest compared with the lowest tertiles of Quetelet index were: 2.1 (95 percent confidence interval [CI] = 1.4-3.2) and 1.7 (CI = 1.1-2.5), at ages 15-29 and in prediagnostic years, respectively. These associations were additive and independent of socioeconomic status. Men who were above the median Quetelet index in 1942 and 1972 had an OR of 2.7 (CI = 1.8-4.0), compared with those who were below the median in both periods. This study provides further evidence for an association of obesity with colon cancer in men and suggests that this association is limited to the sigmoid colon and may be related to both early and late events of colon carcinogenesis.

Colon cancer incidence: recent trends in the United States

Between 1976-78 and 1985-87, the age-adjusted incidence rates of invasive colon cancer in the United States rose by 15 percent, 3 percent, 21 percent, and 16 percent among White males, White females, Black males, and Black females, respectively. The increases in incidence occurred in all age groups over age 54 and affected each of the major subsites of the colon nearly equally. The larger rates of increase have resulted in higher incidence among Blacks than Whites by the mid-1980s and an increasingly greater excess of this cancer in males. Trends toward earlier diagnosis of invasive colon cancer were found, with increasing rates for localized and regional diseases coupled with stable or decreasing distant-stage disease-rates. The incidence of in situ colon cancer also rose substantially. The findings suggest that changes in diagnostic trends and risk-factor prevalence may be contributing to these patterns, and that the era when colon cancer predominated among White females is clearly over.