T Byers

University of Colorado Hospital, Denver, Colorado, United States

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Publications (84)1166.26 Total impact

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    ABSTRACT: to evaluate the effectiveness of a cardiovascular disease (CVD) risk factor reduction program for financially disadvantaged women. The program included cholesterol and blood pressure assessments and tailored physical activity and nutrition interventions. Women who attended selected National Breast and Cervical Cancer Early Detection Program sites in North Carolina and Massachusetts received either enhanced physical activity and nutrition interventions (EI) or minimum interventions (MI). The effectiveness of EI was assessed by pooling data from the North Carolina and Massachusetts projects after 1 year, and a mixed models analysis of covariance was used to compare changes in CVD risk factors across groups. The blood pressure, total cholesterol, and high-density lipoprotein cholesterol profiles of both groups improved, body weight was maintained, and smoking declined. The 10-year estimated coronary heart disease death rate (per 1,000 women) at baseline was 64.8 for the El group and 61.9 for the MI group. The rate declined by 3.5 deaths per 1,000 for the EI and 0.7 per 1,000 for the MI. Although the decline was statistically significant for the EI group, the difference between groups was not significant. Further lifestyle intervention research targeting financially disadvantaged women is needed.
    Journal of the American Medical Women's Association (1972) 02/2001; 56(4):161-5.
  • T Byers, F R Hirsch
    Cancer Practice 01/2001; 9(2):97-9.
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    ABSTRACT: Updates to the American Cancer Society (ACS) guidelines regarding screening for the early detection of prostate, colorectal, and endometrial cancers, based on the recommendations of recent ACS workshops, are presented. Additionally, the authors review the “cancer-related check-up,” clinical encounters that provide case-finding and health counseling opportunities. Finally, the ACS is issuing an updated narrative related to testing for early lung cancer detection for clinicians and individuals at high risk of lung cancer in light of emerging data on new imaging technologies.Although it is likely that current screening protocols will be supplanted in the future by newer, more effective technologies, the establishment of an organized and systematic approach to early cancer detection would lead to greater utilization of existing technology and greater progress in cancer control.
    CA A Cancer Journal for Clinicians 01/2001; 51(1):38-75. · 153.46 Impact Factor
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    ABSTRACT: To estimate the effect of intentional weight loss on mortality in overweight individuals with diabetes. We performed a prospective analysis with a 12-year mortality follow-up (1959-1972) of 4,970 overweight individuals with diabetes, 40-64 years of age, who were enrolled in the American Cancer Society's Cancer Prevention Study I. Rate ratios (RRs) were calculated, comparing overall death rates, and death from cardiovascular disease (CVD) or diabetes in individuals with and without reported intentional weight loss. Intentional weight loss was reported by 34% of the cohort. After adjustment for initial BMI, sociodemographic factors, health status, and physical activity, intentional weight loss was associated with a 25% reduction in total mortality (RR = 0.75; 95% CI 0.67-0.84), and a 28% reduction in CVD and diabetes mortality (RR = 0.72; 0.63-0.82). Intentional weight loss of 20-29 lb was associated with the largest reductions in mortality (approximately 33%). Weight loss >70 lb was associated with small increases in mortality Intentional weight loss was associated with substantial reductions in mortality in this observational study of overweight individuals with diabetes.
    Diabetes Care 11/2000; 23(10):1499-504. · 7.74 Impact Factor
  • T Byers
    New England Journal of Medicine 05/2000; 342(16):1206-7. · 51.66 Impact Factor
  • T Byers, R Vance, C Bigelow
    Cancer Practice 03/2000; 8(2):96-8.
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    ABSTRACT: To assess prospectively the relation between body mass index, weight gain, repeated intentional weight losses, and the risk of self-reported hypertension, the authors studied 46, 224 women who were participants in the Nurses Health Study II, who were free of hypertension in 1993, and who completed questions on intentional weight losses between 1989 and 1993. Women who reported they had intentionally lost ≥20 lbs (9 kg) ≥3 times were classified as severe weight cyclers. Women who had intentionally lost ≥10 lbs (4.5 kg) ≥3 times, but who did not meet the criteria for severe weight cycling, were classified as mild weight cyclers. Between 1993 and 1995, 1, 107 incident cases of diagnosed hypertension were reported. Body mass index and weight gain, but not weight cycler status, were independently associated with the development of hypertension. For each 10 Ib (4.5 kg) gain in weight between 1989 and 1993, the risk of hypertension increased 20% (odds ratio (OR) = 1.20, 95% confidence interval (Cl) 1.15, 1.24). After adjustment for body mass index and weight gain, the risks associated with mild weight cycling (OR = 1.15, 95% Cl 1.00, 1.33) and severe weight cycling (OR = 1.13, 95% Cl 0.79, 1.61) were small and not significant. Thus, the results of this study offer support for the current weight guidelines and provide further evidence of the health risks associated with excessive weight and weight gain. However, these data do not suggest an independent effect of weight cycling on risk of hypertension. Am J Epidemiol 1999; 150: 573-9.
    American Journal of Epidemiology 10/1999; · 4.78 Impact Factor
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    ABSTRACT: Cancer incidence and mortality rates both began to decline in the U. S. in the early 1990s. Recognizing the unprecedented potential benefits of accelerating this decline, the American Cancer Society (ACS) has set ambitious challenge goals for the American public for a 25% reduction in cancer incidence rates and a 50% reduction in cancer mortality rates by the year 2015. This analysis examined the feasibility of reaching those goals by estimating future changes in cancer rates that can result from past and future reductions in cancer risk factors. Estimates for future declines in cancer risk factors in the U. S. under alternative scenarios were applied to conservative population-attributable risk estimates for cancer incidence and mortality rates in 1990 to estimate cancer rate trends in the year 2015. If the current trends toward a decline in the prevalence of cancer risk factors continue over the next decade, by the year 2015 one can expect a 13% decline in cancer incidence rates and a 21% decline in cancer mortality rates below their 1990 levels. With redoubled efforts to reduce the prevalence of known cancer risk factors further, by the year 2015 cancer incidence rates could be reduced by 19% and cancer mortality rates reduced by 29%. Such redoubled efforts would equate to approximately 100,000 cancer cases and 60,000 cancer deaths prevented each year by the year 2015. Past reductions in cancer risk factors in the U.S. population have led to recent declines in the rates of cancer incidence and mortality in the U.S. Redoubled efforts to act on current knowledge regarding how to prevent, detect, and treat cancer can result in attaining approximately 80% of the ACS challenge goal for cancer incidence rates and 60% of the ACS challenge goal for cancer mortality rates by the year 2015. New findings from cancer research are needed and will have to be applied quickly if the ACS challenge goals are to be met fully.
    Cancer 09/1999; 86(4):715-27. · 5.20 Impact Factor
  • T Byers, B Lyle
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    ABSTRACT: This statement summarizes the key points of discussion among a group of nutritional epidemiologists who met in Washington, DC, for 2 d in October of 1997 to reflect on the role of nutritional epidemiology in the development of dietary recommendations for the public. Although imprecision in the measurement of diet places limits on nutritional epidemiology, no other field of nutritional science can provide direct information on relations between nutrition and health in free-living human populations. Among the nutritional sciences, therefore, epidemiology was regarded as being critically important. Nutritional epidemiology can be improved in the future by the development of more precise measures of long-term dietary exposures, both by improved methods of self-reporting of diet and by the development of more useful biomarkers of long-term nutritional status. There is a need as well to reconsider the applicability of causal criteria as applied to nutritional epidemiology, because many of the important associations between dietary behaviors and chronic diseases cannot necessarily be expected to be either strong or to manifest linear dose-response relations. In the future, scientific evidence from the rapidly growing field of nutritional epidemiology will likely play an increasingly important role in developing nutrition policy and advice for the public.
    American Journal of Clinical Nutrition 07/1999; 69(6):1365S-1367S. · 6.50 Impact Factor
  • T Byers
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    ABSTRACT: Observations of the relations between food choices and health have been made since ancient times, but epidemiology, which can be regarded as the science of systematically studying these relations, has played a key role in official nutritional guidance only in recent years. In the past 20 y the principal goal of nutritional guidance has changed from the prevention of nutritional deficiencies to the prevention of chronic diseases. This evolving purpose of nutritional guidance has demanded that nutritional epidemiology play an increasingly important role. Although no other type of nutritional science can equal epidemiology in the relevance of either the dietary exposures or the health outcomes, substantial problems limit the ability of nutritional epidemiology to convincingly prove causal associations. The classic criteria for causation are often not met by nutritional epidemiologic studies, in large part because many dietary factors are weak and do not show linear dose-response relations with disease risk within the range of exposures common in the population. The most important problem in nutritional epidemiology in the past has been the inaccuracy of dietary assessment. In the future, an additional problem will be the proliferation of hypotheses that can be tested in multiple ways among the many subgroups of the population that can be defined by factors such as age, sex, and genotype. Future progress in our understanding of the relations between diet and health will necessitate improved methods in nutritional epidemiology and a better integration of epidemiologic methods with those used in the clinical nutritional sciences.
    American Journal of Clinical Nutrition 07/1999; 69(6):1304S-1308S. · 6.50 Impact Factor
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    ABSTRACT: A case-control study nested within a large cohort, the American Cancer Society Cancer Prevention Study-1, was conducted to test associations between a family history of cancer and cancer mortality in women. By using logistic regression, the authors analyzed family history, as reported by 429,483 women enrolled in 1959, relative to subsequent mortality through 1972 from cancer within and across multiple sites. The associations between family history and cancer mortality were generally stronger within cancer sites than across cancer sites. Within-site associations were found for breast cancer (odds ratio (OR) = 1.9), colorectal cancer (OR = 1.6), stomach cancer (OR = 1.9), and lung cancer (OR = 1.7). Across-site associations were observed for a family history of 1) breast cancer as a risk factor for ovarian cancer mortality (OR = 1.6), 2) stomach cancer as a risk factor for ovarian cancer mortality (OR = 1.5), and 3) uterine cancer as a risk factor for pancreatic cancer mortality (OR = 1.6). A general pattern of positive associations was observed between a family history of cancer at several sites and subsequent death from pancreatic cancer. These findings support the growing body of evidence from cancer genetics suggesting that inherited cancer-susceptibility genes increase the risk for cancer at many sites and are not specific to cancer risk within a single site.
    American Journal of Epidemiology 04/1999; 149(5):454-62. · 4.78 Impact Factor
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    ABSTRACT: Obesity and rapid weight loss in obese persons are known risk factors for gallstones. However, the effect of intentional, long-term, moderate weight changes on the risk for gallstones is unclear. To study long-term weight patterns in a cohort of women and to examine the relation between weight pattern and risk for cholecystectomy. Prospective cohort study. 11 U.S. states. 47,153 female registered nurses who did not undergo cholecystectomy before 1988. Cholecystectomy between 1988 and 1994 (ascertained by patient self-report). During the exposure period (1972 to 1988), there was evidence of substantial variation in weight due to intentional weight loss during adulthood. Among cohort patients, 54.9% reported weight cycling with at least one episode of intentional weight loss associated with regain. Of the total cohort, 20.1% were light cyclers (5 to 9 lb of weight loss and gain), 18.8% were moderate cyclers (10 to 19 lb of weight loss and gain), and 16.0% were severe cyclers (> or = 20 lb of weight loss and gain). Net weight gain without cycling occurred in 29.3% of women; net weight loss without cycling was the least common pattern (4.6%). Only 11.1% of the cohort maintained weight within 5 lb over the 16-year period. In the study, 1751 women had undergone cholecystectomy between 1988 and 1994. Compared with weight maintainers, the relative risk for cholecystectomy (adjusted for body mass index, age, alcohol intake, fat intake, and smoking) was 1.20 (95% CI, 0.96 to 1.50) among light cyclers, 1.31 among moderate cyclers (CI, 1.05 to 1.64), and 1.68 among severe cyclers (CI, 1.34 to 2.10). Weight cycling was highly prevalent in this large cohort of middle-aged women. The risk for cholecystectomy associated with weight cycling was substantial, independent of attained relative body weight.
    Annals of internal medicine 04/1999; 130(6):471-7. · 13.98 Impact Factor
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    ABSTRACT: Although 25% of US men indicate that they are trying to lose weight, the association between intentional weight loss and longevity in men is unknown. The authors analyzed prospective data from 49,337 overweight (initial body mass index > or =27) white men aged 40-64 years who, in 1959-1960, answered questions on weight change direction, amount, time interval, and intent. Vital status was determined in 1972. Proportional hazards regression estimated mortality rate ratios for men who intentionally lost weight compared with men with no weight change. Analyses were stratified by health status and adjusted for age, initial body mass index, smoking status, alcohol intake, education, physical activity, health history, and physical symptoms. Among men with no reported health conditions (n = 36,280), intentional weight loss was not associated with total, cardiovascular (CVD), or cancer mortality, but diabetes-associated mortality was increased 48% (95% confidence interval (CI) -7% to +133%) among those who lost 20 pounds (9.1 kg) or more; this increase was largely related to non-CVD mortality. Among men with reported health conditions (n = 13,057), intentional weight loss had no association with total or CVD mortality, but cancer mortality increased 25% (95% confidence interval -4% to +63%) among those who lost 20 pounds or more. Diabetes-associated mortality was reduced 32% (95% confidence interval -52% to -5%) among those who lost less than 20 pounds and 36% (95% confidence interval -49% to -20%) among those who lost more than 20 pounds. These results and those from our earlier study in women (Williamson et al., Am J Epidemiol 1995;141:1128-41) suggest that intentional weight loss may reduce the risk of dying from diabetes, but not from CVD. In observational studies, however, it is difficult to separate intentional weight loss from unintentional weight loss due to undiagnosed, underlying disease. Well-designed observational studies, as well as randomized controlled trials, are needed to determine whether intentional weight loss reduces CVD mortality.
    American Journal of Epidemiology 03/1999; 149(6):491-503. · 4.78 Impact Factor
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    ABSTRACT: The quantity-frequency method is commonly used to measure alcohol intake in large surveys. Because of time and space constraints, questionnaires are often shortened by combining questions on all types of alcohol into a single question. We investigated the effect of this practice using data from the Behavioral Risk Factor Surveillance System. We examined data collected from 213,842 respondents to surveys conducted by 32 states and the District of Columbia participating in the years 1987, 1988, 1989 and 1990. The 1987 and 1988 surveys asked questions about respondents' frequency and level of intake of specific alcohol-containing beverages. The 1989 and 1990 surveys asked about the frequency and quantity of intake of alcohol-containing beverages by combining all beverages into a single group. Among drinkers, the mean number of drinks per month was higher for those who were asked beverage-specific questions than for those who were asked grouped-beverage questions (men: 37.0 vs 29.6; women: 17.0 vs 13.9). Caution must be used in comparing level of alcohol intake from surveys in which beverages are not grouped identically.
    Journal of studies on alcohol 02/1999; 60(1):99-102.
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    ABSTRACT: Awareness of hereditary breast cancer genetic testing, of breast cancer risk factors, and of increased level of risk based on family history are necessary before women can seek out genetic services. The aim of this paper is to describe the relationships between family history of breast cancer and awareness of genetic testing, knowledge of breast cancer risk factors, and perceived lifetime risk of breast cancer. An anonymous survey was administered by mail to a random sample of 600 women, 200 from each of three breast cancer family history groups (none, intermediate, and strong), drawn from a population-based registry of 240,000 women enrolled in a mammography screening program in the Denver Metropolitan area in Colorado. Awareness of genetic testing for breast cancer risk assessment was found to be significantly associated with family history of breast cancer, increasing from 35% in the lowest family history risk group to 67% in the group with the strongest familial risk (p = 0.002). In all family history groups, nearly 70% of respondents viewed high-fat diet and smoking as being important in relation to breast cancer risk, but alcohol was seen as being only somewhat important or not important by almost half of all respondents. Having a mother or sister with breast cancer was reported as being extremely or very important by nearly all respondents, regardless of family history. As expected, perceived lifetime risk for developing breast cancer was associated with family history (p = 0.001), but the perception of the lifetime risk for breast cancer was much higher among all of the family history groups than their true risk. In conclusion, educational interventions are needed to heighten women's awareness of genetic testing, to clarify women's knowledge of breast cancer risk factors, especially alcohol, and to reassure many women that their actual breast cancer risk is lower than they might perceive.
    Cancer Detection and Prevention 02/1999; 23(1):22-30. · 2.52 Impact Factor
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    ABSTRACT: We assessed the relation between beta-carotene consumption at various times in life and breast cancer risk by conducting a case-control study nested within a population-based cohort of women screened for breast cancer in Sweden. We conducted a telephone interview with 273 incident breast cancer cases and 371 controls about their diet at various ages throughout their lifetime. Controls were frequency matched to cases on age, month and year of mammography, and county of residence. We used unconditional logistic regression to measure the association between beta-carotene intake and breast cancer risk while adjusting for total energy intake, recency of intake, and the matching variables. Women were at lower risk with increasing levels of reported intake of beta-carotene. This pattern of association between breast cancer and beta-carotene intake was similar at various times before screening. These findings indicate that although diets high in beta-carotene may be associated with lower breast cancer risk, there does not seem to be evidence of a critical time period during which such diets are more relevant.
    Epidemiology 02/1999; 10(1):49-53. · 5.74 Impact Factor
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    ABSTRACT: This study compared fruit and vegetable assessments derived from 4 self-administered questionnaires. Among 102 adolescents, servings of fruits and vegetables assessed by 4 questionnaires were compared with estimates from 24-hour recalls. The prevalence of consuming 5 or more servings of fruits and vegetables a day was underestimated by the questionnaires. Questionnaires asking subjects to recall their diet over the previous year were more effective in ranking subjects (r's > or = .42) than those assessing previous-day diet (r's > or = .30). Brief assessments of fruit and vegetable intake are more useful for ranking subjects than for estimating prevalence of consumption of 5 or more servings per day.
    American Journal of Public Health 08/1998; 88(8):1216-8. · 3.93 Impact Factor
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    ABSTRACT: The authors compared interview reports with hospitalization records of participants in a nationally representative survey to determine the accuracy of self-reports of ischemic heart disease, stroke, gallbladder disease, ulcers, cataract, hip fracture, colon polyps, and cancers of the colon, breast, prostate, and lung. The study cohort consisted of 10,523 participants from the First National Health and Nutrition Examination Survey in 1971-1975 who were aged 25-74 years at the baseline examination and who completed a follow-up interview in 1982-1984. Self-reports of hospitalization for breast cancer were confirmed as accurate for 100% of cases where a hospital record was available. Self-report accuracy was also high for ischemic heart disease (84%), cataract (83%), and hip fracture (81%); it was moderate for lung cancer (78%), prostate cancer (75%), gallbladder disease (74%), colon cancer (71%), and stroke (67%); but it was low for ulcers (54%) and colon polyps (32%). Some of the self-reports of ulcers (20%), hip fracture (9%), ischemic heart disease (7%), and stroke (7%) were found to reflect diagnoses of other conditions of anatomic proximity. Accuracy of self-reports improved with higher levels of education, but was not generally related to age, gender, race, alcohol use, or smoking. The results suggest that self-reports of some diseases can be taken as accurate, but self-reports of other conditions might require medical record verification in epidemiologic follow-up studies.
    American Journal of Epidemiology 06/1998; 147(10):969-77. · 4.78 Impact Factor
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    T Byers, K Gieseker
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    ABSTRACT: The methods used in nutritional epidemiology to study the relations between fatty acids and cancer risk include ecologic studies, case-control studies, cohort studies, and intervention trials examining either intermediate markers of cancer risk or cancer incidence. Each type of study design has its particular strengths and weaknesses. The inaccuracy of estimates of fatty acid intake from the use of dietary questionnaires linked to nutrient databases is a major limitation in nutritional epidemiology. Information on the concentrations of fatty acids in the circulation or in adipose tissue can complement estimations of dietary intake. Cancer prevention studies now underway are designed to test whole-diet effects on neoplasia and will not be able to separate the effects of specific fatty acids from those of other nutrients in the diet. The development of better intermediate markers of cancer risk could enable the use of experimental methods to assess the relation between specific fatty acids and cancer. Research findings as described in the literature are complicated both by the multiple hypotheses that can be tested when assessing fatty acid effects and by the uncertainties of multivariate adjustment. Although there are substantial obstacles to understanding the relations between fatty acid intakes and cancer risk, there is no better species than humans for inference about diet and cancer risk in people.
    American Journal of Clinical Nutrition 01/1998; 66(6 Suppl):1541S-1547S. · 6.50 Impact Factor
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    ABSTRACT: This study aimed to examine the correspondence between seven established risk factors for coronary heart disease (CHD) and CHD mortality among the states in the United States. An ecologic analysis relating CHD risk factor prevalences to CHD mortality rates among 49 states was undertaken in 1991-1992. Approximately 68,000 men and women ages 45-74 were randomly sampled and interviewed by telephone in surveys conducted in 49 states in 1991 and 1992. From these interviews, we estimated state-specific prevalences of smoking, overweight, physical inactivity, hypertension, elevated cholesterol, diabetes, and alcohol abstinence. These seven CHD risk factors were also combined to create a CHD risk index for each state. The main outcome measures were mortality rates from CHD (ICD9 codes 410.0-414.9) in each of 49 states in 1991-1992 for men and women ages 45-74. The analysis was based on multiple linear regression and Spearman's rank-order correlations between the CHD risk factor prevalences, the combined CHD risk index, and the CHD mortality rates among the 49 states. The prevalences of most of the CHD risk factors correlated with CHD mortality rates in the expected directions, and correlations were similar for men and women. The CHD risk index correlated strongly with CHD mortality for both men (r = 0.75) and women (r = 0.80). About 60% of the variance in CHD mortality between the states in the United States (56% for men and 64% for women) is attributable to differences between the states in the prevalences of seven established risk factors for CHD. As state health agencies prioritize resources for chronic disease prevention programs, they should consider the potential benefits of increased efforts to reduce the prevalences of modifiable CHD risk factors in their populations to reduce CHD mortality.
    Preventive Medicine 01/1998; 27(3):311-6. · 3.50 Impact Factor

Publication Stats

5k Citations
1,166.26 Total Impact Points

Institutions

  • 1996–2001
    • University of Colorado Hospital
      Denver, Colorado, United States
    • Uppsala University
      Uppsala, Uppsala, Sweden
  • 1991–2000
    • Centers for Disease Control and Prevention
      • • Division of Diabetes Translation
      • • National Center for Chronic Disease Prevention and Health Promotion
      Druid Hills, GA, United States
  • 1994–1997
    • Uppsala University Hospital
      Uppsala, Uppsala, Sweden
    • National Cancer Institute (USA)
      Maryland, United States
  • 1995
    • University of Minnesota Twin Cities
      • School of Public Health
      Minneapolis, MN, United States
    • Georgia Health Sciences University
      Augusta, Georgia, United States
  • 1993
    • U.S. Department of Health and Human Services
      Washington, Washington, D.C., United States