Showing papers by "Arthur Schatzkin published in 2008"

Physical activity, sedentary behavior, and the risk of colon and rectal cancer in the NIH-AARP Diet and Health Study

Abstract: Objective In order to prospectively investigate physical activity at varying intensities and sedentary behavior in relation to colorectal cancer.

Body Size and Renal Cell Cancer Incidence in a Large US Cohort Study

Abstract: Renal cell cancer (RCC) incidence has increased in the United States over the past three decades. The authors analyzed the association between body mass index (BMI) and invasive RCC in the National Institutes of Health (NIH)-AARP Diet and Health Study, a large, prospective cohort aged 50-71 years at baseline initiated in 1995-1996, with follow-up through December 2003. Detailed analyses were conducted in a subcohort responding to a second questionnaire, including BMI at younger ages (18, 35, and 50 years); weight change across three consecutive age intervals; waist, hip, and waist-to-hip ratio; and height at age 18 years. Incident RCC was diagnosed in 1,022 men and 344 women. RCC was positively and strongly related to BMI at study baseline. Among subjects analyzed in the subcohort, RCC associations were strongest for baseline BMI and BMI recalled at age 50 years and were successively attenuated for BMI recalled at ages 35 and 18 years. Weight gain in early (18-35 years of age) and mid- (35-50 years of age) adulthood was strongly associated with RCC, whereas weight gain after midlife (age 50 years to baseline) was unrelated. Waist-to hip ratio was positively associated with RCC in women and with height at age 18 years in both men and women.

Postpolypectomy Colonoscopy Surveillance Guidelines: Predictive Accuracy for Advanced Adenoma at 4 Years

Abstract: rence within 4 years of follow-up. The probability of advanced adenoma recurrence was 0.09 (95% CI, 0.07 to 0.11) among patients with high-risk adenomas at baseline and 0.05 (CI, 0.04 to 0.06) among those with low-risk adenomas at baseline. The relative risk for advanced adenoma recurrence for patients with high-risk adenomas versus those with low-risk adenomas at baseline was 1.68 (CI, 1.19 to 2.38) when advanced adenoma recurrence was compared with no advanced adenoma recurrence and 1.76 (CI, 1.26 to 2.46) when advanced adenoma recurrence was compared with no adenoma recurrence. The c-statistics for these 2 comparisons were 0.68 and 0.72, respectively. Limitation: Participants were self-selected and had restrictions on the degree of obesity. Conclusion: Although the risk for recurrence of advanced adenoma within 4 years is greater for patients with high-risk adenomas at baseline than for those with low-risk adenomas, the discrimination of this risk stratification scheme is relatively low.

Dietary glycemic index, glycemic load, and risk of cancer: a prospective cohort study.

Abstract: A 20-fold variation (1) in the risk of many cancers across geographic regions suggests complex interactions of nonmodifiable (i.e., age, genetic susceptibility) and modifiable (i.e., diet, physical activity) factors (2). Environmental exposures such as diet might be important in the etiologies of different cancers and could play a key role in cancer prevention (2). There has been some suggestion that 2 dietary characteristics associated with carbohydrate intake—glycemic index and dietary glycemic load—may play a role in cancer etiology, but their precise contribution to cancer risk is unclear (3). The glycemic index is a quantitative assessment of foods based on postconsumption blood glucose levels (4, 5); it is expressed as a percentage of the response to an equivalent carbohydrate portion of a reference food (white bread or glucose) (6). Higher rates of carbohydrate absorption lead to higher rises in blood glucose and higher resulting glycemic index values (4). Glycemic index of the diet is approximately a weighted average of the glycemic index of each food consumed. Glycemic load is the product of the glycemic index of a food and the carbohydrate content of the portion size, divided by 100. Because glycemic load takes into account the amount of intake and the carbohydrate content (7), it may be a better measure than glycemic index to characterize the glycemic effect of the diet. Diets of high glycemic index or glycemic load might increase cancer risk via high circulating blood glucose, increased insulin demand, and bioavailability of insulin-like growth factor-1 (4). During the 2.5- to 3-hour period following consumption, glucose is more completely absorbed from high (e.g., white bread) versus low (e.g., nuts/seeds) glycemic index foods (8). Further, for a given amount of carbohydrate, high glycemic index foods trigger a greater insulin response than do low glycemic index foods. Metabolic studies have suggested that carbohydrates with a high glycemic index increase insulin demand and the risk of insulin resistance and hyperinsulinemia (9–13). Insulin has both direct and indirect mitogenic properties. Chronically elevated concentrations of insulin could increase the risk of cancer by stimulating signaling pathways in the cells that promote tumor development and progression. Elevated insulin also downregulates the level of insulin-like growth factor binding proteins 1 and 2, thereby increasing the bioactivity and bioavailability of insulin-like growth factor-1 (14). High levels of unbound circulating insulin-like growth factor-1 could also be related to tumor promotion and progression (14–16). Moreover, insulin-like growth factor-1 regulates sex hormone binding globulin synthesis in vitro and may increase the bioavailability and levels of unopposed circulating estrogen in the body, which may increase the risk of hormone-related cancers (17, 18). The primary objective of this analysis was to investigate whether glycemic index and glycemic load are related to increased risk of developing a first primary cancer in a prospective cohort of women and men aged 50 years or older, after controlling for potential confounders. We explored the effects of glycemic index and glycemic load for all major cancers. Our hypothesis was that high glycemic index and high glycemic load are associated with increased risk of total cancer and insulin- or hormone-related cancers.

Education and Risk of Cancer in a Large Cohort of Men and Women in the United States

Abstract: Background Education inequalities in cancer incidence have long been noted. It is not clear, however, whether such inequalities persist in the United States, especially for less common malignancies and after adjustment for individual risk factors. Methodology/Principal Findings Within the NIH–AARP Diet and Health Study, we examined the association between education and the risk of developing cancers in a prospective cohort of 498 455 participants who were 50–71 year old and without cancer at enrollment in 1995/96. During a maximum 8.2 years of follow–up we identified 40 443 cancers in men and 18 367 in women. In age-adjusted models, the least educated men (

Dietary Flavonoids and Colorectal Adenoma Recurrence in the Polyp Prevention Trial

Abstract: Two recent case-control studies suggested that some flavonoid subgroups may play a role in preventing colorectal cancer. Previous prospective cohort studies generally reported no association; however, only a small subset of flavonoids was evaluated and partial flavonoid databases were used. We used the newly constructed U.S. Department of Agriculture flavonoid database to examine the association between consumption of total flavonoids, 6 flavonoid subgroups, and 29 individual flavonoids with adenomatous polyp recurrence in the Polyp Prevention Trial. The Polyp Prevention Trial was a randomized dietary intervention trial, which examined the effectiveness of a low-fat, high-fiber, high-fruit, and high-vegetable diet on adenoma recurrence. Intakes of flavonoids were estimated from a food frequency questionnaire. Multivariate logistic regression models (adjusted for age, body mass index, sex, regular non–steroidal anti-inflammatory use, and dietary fiber intake) were used to estimate odds ratios and 95% confidence intervals for both any and advanced adenoma recurrence within quartiles of energy-adjusted flavonoid intake (baseline, during the trial, and change during the trial). Total flavonoid intake was not associated with any or advanced adenoma recurrence. However, high intake of flavonols, which are at greater concentrations in beans, onions, apples, and tea, was associated with decreased risk of advanced adenoma recurrence (4th versus 1st quartile during the trial; odds ratio, 0.24; 95% confidence interval, 0.11, 0.53; Ptrend = 0.0006). Similar inverse associations were observed to a smaller extent for isoflavonoids, the flavonol kaempferol, and the isoflavonoids genistein and formononetin. Our data suggest that a flavonol-rich diet may decrease the risk of advanced adenoma recurrence.

Nonsteroidal anti-inflammatory drugs and breast cancer risk in the National Institutes of Health-AARP Diet and Health Study.

Abstract: By inhibiting cyclooxygenase-2, nonsteroidal anti-inflammatory drugs (NSAIDs) decrease aromatase activity and might reduce breast cancer risk by suppressing estrogen synthesis. Epidemiologic evidence for a protective role of NSAIDs in breast cancer, however, is equivocal. We tested NSAID use for its association with breast cancer incidence in the National Institutes of Health–AARP Diet and Health Study, where 127,383 female AARP (formerly known as the American Association of Retired Persons) members with no history of cancer, aged 51 to 72 years, completed a mailed questionnaire (1996 to 1997). We estimated relative risks of breast cancer for NSAID exposures using multivariate Cox proportional hazards regression models. The state cancer registry and mortality index linkage identified 4,501 primary incident breast cancers through 31 December 2003, including 1,439 estrogen receptor (ER)-positive cancers and 280 ER-negative cancers. Proportional hazards models revealed no statistically significant association between overall NSAIDs and total breast cancer. As cyclooxygenase inhibition by aspirin (but not other NSAIDs) is irreversible, we tested associations by NSAID type. Although we observed no significant differences in risk for daily use (versus nonuse) of aspirin (relative risk = 0.93, 95% confidence interval = 0.85 to 1.01) or nonaspirin NSAIDS (relative risk = 0.96, 95% confidence interval = 0.87 to 1.05), risk of ER-positive breast cancer was significantly reduced with daily aspirin use (relative risk = 0.84, 95% confidence interval = 0.71 to 0.98) – a relationship not observed for nonaspirin NSAIDS. Neither aspirin nor nonaspirin NSAIDs were associated with risk of ER-negative breast cancer. Breast cancer risk was not significantly associated with NSAID use, but daily aspirin use was associated with a modest reduction in ER-positive breast cancer. Our results provide support for further evaluating relationships by NSAID type and breast cancer subtype.

Prospective study of physical activity and risk of postmenopausal breast cancer.

Abstract: Introduction To prospectively examine the relation of total, vigorous and non-vigorous physical activity to postmenopausal breast cancer risk.

Fat, Protein, and Meat Consumption and Renal Cell Cancer Risk: A Pooled Analysis of 13 Prospective Studies

Abstract: Background Results of several case-control studies suggest that high consumption of meat (all meat, red meat, or processed meat) is associated with an increased risk of renal cell cancer, but only a few prospective studies have examined the associations of intakes of meat, fat, and protein with renal cell cancer. Methods We conducted a pooled analysis of 13 prospective studies that included 530,469 women and 244,483 men and had follow-up times of up to 7-20 years to examine associations between meat, fat, and protein intakes and the risk of renal cell cancer. All participants had completed a validated food frequency questionnaire at study entry. Using the primary data from each study, we calculated the study-specific relative risks (RRs) for renal cell cancer by using Cox proportional hazards models and then pooled these RRs by using a random-effects model. All statistical tests were two-sided. Results A total of 1,478 incident cases of renal cell cancer were identified (709 in women and 769 in men). We observed statistically significant positive associations or trends in pooled age-adjusted models for intakes of total fat, saturated fat, monounsaturated fat, polyunsaturated fat, cholesterol, total protein, and animal protein. However, these associations were attenuated and no longer statistically significant after adjusting for body mass index, fruit and vegetable intake, and alcohol intake. For example, the pooled age-adjusted RR of renal cell cancer for the highest vs the lowest quintile of intake for total fat was 1.30 (95% confidence interval [CI] = 1.08 to 1.56; P(trend) = .001) and for total protein was 1.17 (95% CI = 0.99 to 1.38; P(trend) = .02). By comparison, the pooled multivariable RR for the highest vs the lowest quintile of total fat intake was 1.10 (95% CI = 0.92 to 1.32; P(trend) = .31) and of total protein intake was 1.06 (95% CI = 0.89 to 1.26; P(trend) = .37). Intakes of red meat, processed meat, poultry, or seafood were not associated with the risk of renal cell cancer. Conclusions Intakes of fat and protein or their subtypes, red meat, processed meat, poultry, and seafood are not associated with risk of renal cell cancer.

Physical activity during adulthood and adolescence in relation to renal cell cancer

Abstract: 3093 Background: Evidence for a relationship between physical activity and renal cell cancer has been inconsistent. Methods: We examined physical activity in relation to renal cell cancer in a cohort of 499,437 participants (297,926 men and 201,511 women) aged 50-71 at study baseline from the National Institutes of Health-AARP Diet and Health Study. At baseline (1995-1996), participants completed a questionnaire inquiring about current frequency of exercise/ sports activities of at least 20 minutes duration, intensity of daily routine activity, and frequency of activity during adolescence (between ages 15 and 18). Cox regression was used to estimate relative risks (RR) and 95% confidence intervals (95% CI). During up to 8.2 years of follow-up, 1,267 cases were ascertained (945 in men and 322 in women). Results: In multivariate models adjusted for renal cell cancer risk factors (i.e. gender, age, race, smoking, BMI, height, history of diabetes, history of hypertension, and protein intake) we observed that current exercise/ sports, routine physical activity, and activity during adolescence were associated with a reduced risk of renal cell cancer. The multivariate RRs of the highest activity level as compared with the lowest activity level were 0.76 (95% CI: 0.63, 0.91, P trend =0.08) for exercise/ sports, 0.85 (95% CI: 0.58, 1.23, P trend =0.02) for routine physical activity, and 0.82 (95% CI: 0.68, 0.99, P trend =0.03) for activity during adolescence. Assuming a causal relationship, our data suggest that 10% of renal cell cancers would be prevented if all persons exercised three or more times per week for 20 or more minutes and engaged in light or moderate routine activities, as recommended by public health guidelines. Conclusion: Increased physical activity, including activity during adolescence, is associated with reduced risk of renal cell cancer.

Physical Activity during Adulthood and Adolescence in Relation to Renal Cell Cancer

Abstract: Evidence for a relation between physical activity and renal cell cancer has been inconsistent. The authors examined physical activity in relation to renal cell cancer in a large, prospective US cohort study of 482,386 participants (289,503 men and 192,883 women) aged 50–71 years at baseline (1995–1996). At baseline, participants reported their frequency of exercise of at least 20 minutes' duration, intensity of daily routine activity, and frequency of physical activity during adolescence. During 8.2 years of follow-up (through December 2003), 1,238 cases of renal cell cancer were ascertained. In multivariate Cox regression models adjusted for renal cell cancer risk factors, the authors observed that current exercise, routine physical activity, and activity during adolescence were associated with a reduced risk of renal cell cancer. The multivariate relative risks for the highest activity level as compared with the lowest were 0.77 (95% confidence interval (CI): 0.64, 0.92; ptrend = 0.10) for current exercise, 0.84 (95% CI: 0.57, 1.22; ptrend = 0.03) for routine physical activity, and 0.82 (95% CI: 0.68, 1.00; ptrend = 0.05) for activity during adolescence. The authors conclude that increased physical activity, including activity during adolescence, is associated with reduced risk of renal cell cancer.

The role of dietary measurement error in investigating the hypothesized link between dietary fat intake and breast cancer--a story with twists and turns.

Abstract: The association between dietary fat and breast cancer is one of the most controversial hypotheses in nutritional epidemiology. In this editorial, the authors review the evidence from animal and human studies, including international correlation, case-control, cohort studies, intervention trials, and studies comparing dietary assessment instruments. The authors emphasize the importance of the role played by measurement error arising from assessing dietary habits using self-reported questionnaires, as it can distort estimated associations, not necessarily towards the absence of an association. They describe the twists and turns of the dietary fat and breast cancer debate that have revolved around this issue.

Past body mass index and risk of mortality among women.

Abstract: Epidemiologic studies of body mass index (BMI) in relation to mortality commonly exclude persons with health conditions and/or a history of smoking to prevent bias resulting from illness-related weight loss (‘reverse causation’) Analysis of BMI from an earlier time period may minimize reverse causation without requiring exclusion of participants based on disease or smoking history We prospectively examined BMI based on technician measurements of weight and height from 10 years prior to start of follow-up in relation to subsequent mortality in a cohort of 50 186 women who were 40–93 years old at baseline in 1987–1989 Deaths were ascertained through the US National Death Index Proportional hazards regression was used to estimate hazard ratios (HRs) of mortality, adjusted for age, education, race/ethnicity, income, menopausal hormone use, smoking and physical activity During 10 years of follow-up through 1997, 5201 women died Overall, we observed a J-shaped association between BMI and mortality, with increased risk for women who were underweight, overweight or obese The HRs and 95% confidence intervals of mortality for BMI categories of <185, 185–209, 210–234 (reference), 235–249, 250–274, 275–299, 300–349 and 350+ kg m−2 were 143 (119, 172), 107 (098, 117), 100 (reference), 110 (100, 120), 120 (111, 131), 123 (111, 137), 160 (144, 177) and 192 (164, 224) There was little evidence that pre-existing conditions (heart disease, diabetes and/or cancer) or smoking history modified the past BMI and mortality relation (P=054 and 076) In this large cohort of women, BMI based on technician measurements of weight and height from 10 years prior to baseline showed increased risk for mortality across the range of overweight and obesity, regardless of disease and smoking history Observed associations between overweight, obesity and mortality in healthy individuals may also apply to persons with a history of disease or smoking

Physical activity and head and neck cancer risk

Abstract: To investigate the relation of physical activity to head and neck cancer. We prospectively examined the association between physical activity and head and neck cancer in 487,732 men and women, who, at baseline in 1995–1996, were 50–71 years old and free of cancer and emphysema. Follow-up occurred through 31 December 2003. During follow-up, 1,249 participants developed head and neck cancer, of which 42.0%, 18.9%, and 32.5% were located in the oral cavity, pharynx, and larynx, respectively. In analyses adjusted for age and gender, the relative risks (RR) of head and neck cancer for increasing frequency of physical activity (0, < 1, 1–2, 3–4, and ≥5 times per week) were 1.0 (reference), 0.76, 0.66, 0.57, and 0.62 (95% CI = 0.52–0.74), respectively (p for trend < 0.001). After multivariate adjustment including smoking, the relation was attenuated and became statistically non-significant (RR comparing extreme physical activity categories = 0.89, 95% CI = 0.74–1.06; p for trend = 0.272). In analyses of head and neck cancer subtypes, the corresponding RRs for cancers of the oral cavity, pharynx, and larynx were 0.98 (95% CI = 0.75–1.29), 0.70 (95% CI = 0.45–1.08), and 0.82 (95% CI = 0.59–1.13), respectively. Our findings suggest that physical activity is unlikely to play an important role in the prevention of head and neck cancer.