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Biomedical subjects

B J Caan

Publications and source records attributed to B J Caan.

16 recordsLinked to original sources
PubMed1998

Body size and the risk of colon cancer in a large case-control study.

OBJECTIVE: To investigate the risks of height, weight and body fat distribution associated with colon cancer in subcategories of gender, age and site in the colon. Interaction with family history of colorectal cancer is also examined. DESIGN: Case-control study of diet, anthropometry and colon cancer risk. SUBJECTS: Nineteen hundred and eighty-three colon cancer cases (age 30-79 y) and 2400 age and gender matched population controls. MEASUREMENTS: Height, weight and waist and hip circumferences were obtained by trained interviewers. Body Mass Index (BMI) and Waist-Hip Ratio (WHR) were calculated. RESULTS: Of all anthropometric measurements examined, only BMI was consistently associated with an increased risk of colon cancer. The test for trend for BMI was significant for men and women overall and for the majority of subgroups examined. In younger persons those with a family history of colorectal cancer had a greater risk of colon cancer associated with BMI (Men odds ratio (OR) = 7.76, 95% confidence interval (CI) 2.60, 23.1; Women OR = 4.85, 95% CI 2.33, 10.12) comparing the third tertile to the first, than those with no family history (Men OR = 1.70, 95% CI 1.25, 2.32; Women OR = 1.53, 95% CI 1.22, 1.92). WHR, after controlling for BMI was not associated with colon cancer in men, and was associated with a slight increase in women (primarily in those with distal tumors). CONCLUSION: This study contributes to mounting evidence that excess weight is associated with an increased risk of colon cancer.

Adult↗
PubMed1997

Dietary energy sources and colon cancer risk.

Because energy-contributing nutrients are highly correlated with total energy, the association with colon cancer from energy versus other components of energy-providing nutrients is often not clear. Dietary data from a population-based case-control study of colon cancer were analyzed in subjects from California, Utah, and Minnesota in 1991-1994 to assess the colon cancer risk associated with consumption of energy, fat, protein, and carbohydrate. After adjustment for long-term physical activity, total energy intake increased risk of colon cancer in men (odds ratio = 1.74, 95% confidence interval 1.14-2.67 for highest vs. lowest quartile) and in women (odds ratio = 1.70, 95% confidence interval 1.07-2.70). Various methods of analysis suggested that intakes of individual sources of energy (dietary fat, protein, and carbohydrate) were not associated with colon cancer risk after total energy intake was taken into account. People who consumed a high-calorie diet that was dense in fiber and calcium appeared to be at lower risk than people with the same caloric intake who consumed smaller amounts of dietary fiber and calcium. Individuals with a first-degree relative with colorectal cancer, especially those diagnosed at a younger age, were at a greater risk from a diet high in energy than were individuals without a family history of colorectal cancer.

Adult↗
PubMed1997

Performance of a shortened telephone-administered version of a quantitative food frequency questionnaire.

PURPOSE: We evaluated the performance of a telephone-administered food frequency questionnaire in a study of 190 men and women, 30-79 years of age, who participated as controls in a study of colon cancer. METHODS: The telephone version of the questionnaire was modified from a longer food frequency questionnaire originally administered in person to each of the participants. One month later, the telephone questionnaire was administered to a subgroup of 190 participants and readministered to 169 members of the subgroup two weeks later to assess the reproducibility and comparative validity of the instrument. RESULTS: The unadjusted correlation for energy between the original in-person full food frequency questionnaire and the abbreviated telephone version was 0.69. The median energy intake from the telephone version was 17% lower in men and 23% lower in women. The energy and sex-adjusted correlation coefficients for other nutrients ranged from 0.45 for vitamin E to 0.78 for fiber. The intraclass correlation coefficients to measure reproducibility ranged from 0.62 for animal protein to 0.83 for folate. CONCLUSIONS: These data indicate that this brief, telephone-administered questionnaire is reproducible and provides a ranking of nutrient intake comparable to that provided by a full in-person interview.

Adult↗
PubMed1997

Hormone replacement therapy, reproductive history, and colon cancer: a multicenter, case-control study in the United States.

Hormonal factors have been inconsistently associated with colon cancer risk in women. The associations between reproductive events, menstrual factors, exogenous hormones, and colon cancer were evaluated in a large case-control study (894 female cases and 1,120 female age-matched population-based controls) in the United States, stratifying by age at diagnosis, tumor site, family history and other potential risk factors. Overall, higher parity was associated with a marginally decreased risk of colon cancer (five or more births compared with nulliparous: odds ratio [OR] = 0.75, 95 percent confidence interval [CI] = 0.53-1.06) after adjusting for age at diagnosis, family history of colorectal cancer, vigorous lifetime physical activity, body mass index (BMI) (wt/ht1.5), total energy intake, and aspirin use. No important associations were observed for other reproductive or menstrual events. An inverse association between recent use of hormone replacement therapy (HRT) and colon cancer was observed (OR = 0.71, CI = 0.56-0.89). Although interaction terms were not significant, this inverse association appeared to be more pronounced for those with an older age at diagnosis; for those without a first-degree relative with colorectal cancer; and for those with a relatively low BMI. The reduced risk associated with HRT use did not appear to be explained by other behaviors related to HRT use.

Adult↗
PubMed1997

Plant foods and colon cancer: an assessment of specific foods and their related nutrients (United States).

Plant foods have been associated inversely with colon cancer. Since a major focus of this study was to identify components of plant foods which may account for their association with colon cancer, nutrients which are commonly found in plant foods also were evaluated. A population-based case-control study was conducted in Northern California, Utah, and the 'Twin Cities' area of Minnesota (United States). Complete data were available from interviewer-administered questionnaires on 1,993 cases and 2,410 controls. Higher intakes of vegetables (for highest relative to lowest quintile of intake) were associated inversely with colon cancer risk: the odds ratio (OR) was 0.7 for both men (95 percent [CI] confidence interval = 0.5-0.9) and women (CI = 0.5-1.0). Associations were stronger among those with proximal tumors. Total fruit intake was not associated with colon cancer risk although, among men, higher levels of whole grain intake were associated with a decreased risk (OR = 0.6, CI = 0.4-0.9 for older men); high intakes of refined grains were associated with an increased risk (OR = 1.5, CI = 1.1-2.1). Dietary fiber intake was associated with a decreased risk of colon cancer: OR = 0.5 (CI = 0.3-0.9) for older men; OR = 0.7 (CI = 0.4-1.2) for older women; OR = 0.6 (CI = 0.4-1.0) for men with proximal tumors; OR = 0.5 (CI = 0.3-0.9) for women with proximal tumors. Other nutrients, for which plant foods were the major contributor--such as vitamin B6, thiamin, and niacin (women only)--also were associated inversely with colon cancer. Neither beta-carotene nor vitamin C was protective for colon cancer. Adjustment of plant foods for nutrients found in plant foods or for supplement use did not appreciably alter the observed associations between plant foods and colon cancer.

Adult↗
PubMed1997

Dietary sugar and colon cancer.

It has been hypothesized that levels of triglycerides, glucose, and insulin are associated with risk of colon cancer and that diets high in simple sugars increase risk of colon cancer because of their impact on these factors. Limited epidemiological evidence supports the association between simple carbohydrates and risk of colon cancer. Using data from a population-based case-control study (n = 1993 cases and 2410 controls), we examined the associations between dietary sugars, foods containing high level of sugars, and dietary glycemic index (GI) and colon cancer. A dietary GI was developed to estimate metabolic response to a diet that may increase plasma glucose levels. Dietary data were obtained using a validated diet history questionnaire. High levels of sucrose intake were associated with increased risk of colon cancer among younger men [odds ratio (OR) for highest quintile relative to lowest, 1.59; 95% confidence interval (CI), 1.07-2.37]. There was also a trend of increasing colon cancer risk associated with a higher sucrose:dietary ratio for proximal tumors in both men and women. Individuals with proximal tumors who consumed a diet ranked as having a high GI were at increased risk (for men, comparing highest quintile to lowest quintile: OR, 1.58; 95% CI, 1.06-2.36; P trend 0.04; for women: OR, 1.72; 95% CI, 1.11-2.67; P trend 0.04). Those at greatest risk from a high dietary GI were those who were sedentary (for men, relative to those who were most active and had a low-GI diet: OR, 3.46; 95% CI, 1.78-6.70; for women: OR, 2.00; 95% CI, 0.98-4.07). We also observed that people who had a high sucrose: dietary fiber ration and who also were sedentary and had a large body mass index were at increased risk (OR, 4.58; 95% CI, 2.33-8.98) relative to those who had a low sucrose:dietary fiber ratio, were active, and had low body mass indices. These findings support previous reports that dietary sugars, especially diet high in simple carbohydrates relative to complex carbohydrates, increase risk of colon cancer, possibly through their impact on plasma glucose levels.

Adult↗
PubMed1996

A description of age, sex, and site distributions of colon carcinoma in three geographic areas.

BACKGROUND: Site of the carcinoma within the colon in relation to age and sex may provide clues into the etiology of the disease. Incidence of colon carcinoma by age, sex, and tumor site at a population-based level are reported infrequently. The goal of this study was to describe the distribution of colon carcinoma (excluding cancers of the rectosigmoid junction and rectum) by age at diagnosis, sex, and site of the tumor within the colon. These factors were also evaluated in conjunction with disease stage at the time of diagnosis. METHODS: Data from three geographically distinct populations were used to describe rates of colon carcinoma and the distribution of tumors by age, tumor site, and stage at diagnosis. All colon carcinoma cases diagnosed within a 3-year period within the areas are included. RESULTS: Approximately 50% of all cancers in men and greater than 50% of cancers in women were in the proximal segment of the colon. Men who were diagnosed prior to age 50 and both men and women diagnosed at age 70 or older had predominantly proximal cancers. People with proximal cancers and people diagnosed prior to age 50 were more likely to have more advanced disease. CONCLUSIONS: Both men and women have more proximal cancers with advancing age, which are associated with more advanced disease. Observed trends in cancer site distributions could reflect screening practices, environmental and genetic factors, or a combination of these variables.

Adult↗
PubMed1995

Response rates among control subjects in case-control studies.

Response rates are an important component of epidemiologic research. The purposes of this study are (a) to evaluate how response rates are defined and calculated for control subjects in epidemiologic case-control studies, and (b) to explore factors that may impact response in epidemiologic studies. Our results show that the method of control subject selection has an impact on study response. Gender of respondent does not appear to impact response rates. However, response rates are generally worse for individuals less than 45 years old. Methods used to calculate response have a great impact on "response rate"; therefore, it is important for researchers to define exactly what the reported response rates represent and how they are derived so that data can be interpreted appropriately.

Adult↗
PubMed1995

Dietary antioxidants and plasma lipids: the CARDIA Study.

OBJECTIVE: To determine if dietary antioxidants play a role in preventing coronary heart disease (CHD) by having an impact on lipid levels. METHODS: Data from the Coronary Artery Risk Development in Young Adults (CARDIA) Study were used to assess the associations of reported intake of vitamins A, C, E and beta carotene, and their use in supplements, with lipid levels in a black and white, healthy adult (18 to 30 years of age at the baseline examination) population. RESULTS: After adjusting for age, education level, physical activity, body size, alcohol consumption and caloric intake, vitamin A, beta carotene, and vitamin C (white women) intake were directly associated with HDL-cholesterol levels among women who smoked cigarettes, with the strongest associations being observed for white women. Black men who took supplements of vitamins A and C and did not smoke cigarettes had significantly higher HDL-cholesterol levels compared to those in the lowest levels of dietary intake. Although vitamin E was associated with higher levels of HDL-cholesterol, the association was only of borderline significance among white men who smoked cigarettes (p = 0.06). We did not observe any consistent associations between antioxidants and other plasma lipids, including total cholesterol, LDL-cholesterol, or triglycerides. CONCLUSIONS: We conclude that dietary antioxidants are associated with HDL-cholesterol levels in some subsets of the population, although these associations may be operating in conjunction with other lifestyle behaviors.

Adolescent↗
PubMed1994

Objective system for interviewer performance evaluation for use in epidemiologic studies.

In this paper, the authors present an objective system to evaluate interviewer performance for use in epidemiologic studies. With this quality control system, all study interviews are audio-taped, and a random sample of interviews are coded according to interviewer behaviors, such as whether the interviewer asked the questions exactly as written and used the probes appropriately. With the use of data obtained from a large case-control study of colon cancer, the authors observed that 94.2% of all questions were asked in the same manner by all interviewers and that 89.5% of all probing behaviors were appropriate. They show that questions that required additional interviewer behaviors were more likely to result in variation in response that can be attributed to the interviewer. These findings have implications for study design and interpretation of study results. From simulations, the authors have estimated the impact of uncorrected interviewer variability on study power and ability to detect disease associations. Uncorrected interviewer variability could decrease study power from 84% to 56%. From simulations, the authors observed that odds ratios could be biased downward from 1.8 to 1.3. These findings illustrate the importance of using a continuous quality control program in epidemiologic research.

Epidemiologic Methods↗
PubMed1994

A computerized diet history questionnaire for epidemiologic studies.

OBJECTIVE: To describe methods used to computerize the diet history questionnaire developed for the Coronary Artery Risk Factor Development in Young Adult (CARDIA) study and to describe quality-control procedures used in conjunction with dietary assessment. DESIGN: The computerized diet history is being used in a case-control study. Because of the computerized nature of the questionnaire, we developed quality-control procedures that incorporate listening to an audiotape of the interview while visually reviewing recorded data. SETTING: Three centers involved in a population-based epidemiologic study of colon cancer. SUBJECTS: Men and women between the ages of 30 and 79 years. RESULTS: Quality-control results showed that 100% of the computerized forms would be free of errors if the data were subjected to visual review only. Probing errors, which accounted for 47.3% of all errors, were the most commonly encountered errors. In probing errors the interviewer did not probe in a nondirective manner, or the interviewer failed to verify responses that might be considered questionable. APPLICATIONS: The CARDIA diet history was computerized for use in epidemiologic studies of the association between diet and disease. Review of the audiotapes of the interviews showed that most errors made in obtaining a dietary assessment were not detectable from visual review of the data. Although the quality-control procedures were developed for a computerized diet history questionnaire, they are applicable to other dietary assessment methods.

Adult↗
PubMed1994

A comparison of two methods to ascertain dietary intake: the CARDIA Study.

Data on dietary intake were collected in the Coronary Artery Risk Development in Young Adults (CARDIA) Study at the baseline examination in 1985-86 and again at the second examination 2 years later. At baseline, a diet history questionnaire developed for the CARDIA study was used; at the second exam the NCI (Block) food frequency questionnaire was used. The purpose of the present report is to compare the estimated nutrient intakes obtained with the two instruments; to compare correlations of nutrient intakes obtained at the two exams with those observed for other lifestyle and physiological variables also measured 2 years apart; and to assess ability to test hypotheses relating 2-year changes in risk factors to between-exam differences in reported nutrient intakes. Mean levels of reported intake were generally greater for both blacks and whites on the CARDIA diet history than on the Block food frequency. Rank order correlations of reported nutrient intakes between the two questionnaires indicated greater consistency between instruments for whites (r's ranging between 0.35 and 0.52) than for blacks (r's ranging between 0.29 and 0.45). Correlations over time for nutrients were smaller than those observed for body size measures and lipid levels but were similar in magnitude to those for blood pressure, physical activity, and life events. At both exams, total caloric intake was positively associated with physical activity (range of r's for CARDIA were 0.07 for white women to 0.23 for black men, the range of r's for Block were 0.06 for women to 0.11 for white men). Using data from the two examinations, 2-year changes in total plasma cholesterol were significantly related to 2 year changes in Keys scores. The results of this comparison are useful in that they show similarities and differences between two instruments developed to gather dietary intake data. The study also illustrates the need to monitor young adults during a time when rapid changes occur in many lifestyle and physiologic factors.

Adult↗
PubMed1992

Associations of body fat and its distribution with dietary intake, physical activity, alcohol, and smoking in blacks and whites.

Cross-sectional associations between body fat and its distribution and environmental factors influencing energy balance were examined in 5115 young adults. Protein was directly associated with body mass index (BMI) in all race and sex groups (P less than 0.01) after age, education, cigarette-smoking status, alcohol intake, and physical activity were adjusted for. Carbohydrate intake was inversely associated with BMI in males (P = 0.02). Total physical activity was inversely associated with BMI in white women and with skinfold-thickness measures (P less than 0.01) in all groups. Waist-to-hip-circumference ratio (WHCR) was positively associated with total kilojoules (kilocalories) in women, inversely associated with percent of kilojoules (kilocalories) from carbohydrates in whites, grams of crude fiber/4184 kJ (1000 kcal) (except in black men), and physical activity (except in white women). WHCR was directly associated with cigarette smoking except in black men, and with total alcohol intake in men. Beer was consistently associated with WHCR in all race and sex groups.

Adipose Tissue↗
PubMed1991

Meat consumption and its associations with other diet and health factors in young adults: the CARDIA study.

Using cross-sectional data from the longitudinal Coronary Artery Risk Development in Young Adults (CARDIA) study, we assessed associations between meat consumption and other dietary- and health-status indicators. Less than one percent of this sample (n = 32) ate no red meat or poultry, and another 1% (n = 47) ate red meat or poultry less than once per week. Individuals who ate red meat and poultry less than once per week were less likely to drink alcohol (P = 0.003); reported more physical activity (P less than or equal to 0.001); had lower [corrected] Keys scores (P less than or equal to 0.001); consumed diets higher in carbohydrates, starch, fiber, vitamins A and C, and calcium and lower in energy, fat, and protein (P less than or equal to 0.001); had smaller body sizes as indicated by the body mass index [calculated as wt(kg)/ht(m2)] (P = 0.01); and had lower concentrations of total serum cholesterol (P = 0.001), low-density-lipoprotein cholesterol (P = 0.001), and triglycerides (P = 0.015) compared with individuals who consumed meat more frequently.

Adult↗
PubMed1989

Caffeinated beverages and low birthweight: a case-control study.

A case-control study, examining the effect of first trimester maternal caffeine consumption on low birthweight, was performed in the Kaiser Permanent Medical Care Program. Heavy consumption (greater than 3 servings/day) of coffee, cola and greater than 300 mg/day of caffeine from all sources (coffee, tea and cola) was associated with a marginally increased risk of low birthweight. Our data support previous findings of a modest effect of caffeine consumption on fetal growth.

Adult↗