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G A Colditz

Publications and source records attributed to G A Colditz.

At least 181 records · Page 10Linked to original sources
PubMed1999

Alcohol consumption in relation to breast cancer risk in a cohort of United States women 25-42 years of age.

We evaluated current and past alcohol consumption prospectively in relation to breast cancer risk among 116,671 women ages 25-42 years old at enrollment in 1989. During 6 years of follow-up, 445 cases of invasive breast cancer were identified. For alcohol consumption in the previous year, the multivariate relative risk associated with more than 20 g/day (approximately 10 drinks/week) was 1.23 (95% confidence interval, 0.68-2.21); the P for trend was 0.85. For average lifetime alcohol consumption, the multivariate relative risk associated with consumption of 10 or more drinks/week was 1.20 (95% confidence interval, 0.69-2.11); the P for trend was 0.18. We examined drinking in several time periods of life; only drinking at ages 23-30 was significantly positively associated with risk. Although this may represent a chance finding, it merits further study. Because drinking levels in this population were low, we had limited information on heavier drinking. Our results suggest that there is unlikely to be a large effect of moderate alcohol consumption on breast cancer risk among young women, although a modest effect cannot be excluded. The association between alcohol consumption and breast cancer is unlikely to be substantially stronger among premenopausal women than among postmenopausal women.

Adolescent↗
PubMed1998

Abdominal adiposity and coronary heart disease in women.

CONTEXT: Obesity is a well-established risk factor for coronary heart disease (CHD), but whether regional fat distribution contributes independently to risk remains unclear. OBJECTIVE: To compare waist-hip ratio (WHR) and waist circumference in determining risk of CHD in women. DESIGN AND SETTING: Prospective cohort study among US female registered nurses participating in the Nurses' Health Study conducted between 1986, when the nurses completed a questionnaire, and follow-up in June 1994. PARTICIPANTS: A total of 44702 women aged 40 to 65 years who provided waist and hip circumferences and were free of prior CHD, stroke, or cancer in 1986. MAIN OUTCOME MEASURES: Incidence of CHD (nonfatal myocardial infarction or CHD death). RESULTS: During 8 years of follow-up 320 CHD events (251 myocardial infarctions and 69 CHD deaths) were documented. Higher WHR and greater waist circumference were independently associated with a significantly increased age-adjusted risk of CHD. After adjusting for body mass index (BMI) (defined as weight in kilograms divided by the square of height in meters) and other cardiac risk factors, women with a WHR of 0.88 or higher had a relative risk (RR) of 3.25 (95% confidence interval [CI], 1.78-5.95) for CHD compared with women with a WHR of less than 0.72. A waist circumference of 96.5 cm (38 in) or more was associated with an RR of 3.06 (95% CI, 1.54-6.10). The WHR and waist circumference were independently strongly associated with increased risk of CHD also among women with a BMI of 25 kg/m2 or less. After adjustment for reported hypertension, diabetes, and high cholesterol level, a WHR of 0.76 or higher or waist circumference of 76.2 cm (30 in) or more was associated with more than a 2-fold higher risk of CHD. CONCLUSIONS: The WHR and waist circumference are independently associated with risk of CHD in women.

Abdomen↗
PubMed1998

Meta-analysis of multiple outcomes by regression with random effects.

Earlier work showed how to perform fixed-effects meta-analysis of studies or trials when each provides results on more than one outcome per patient and these multiple outcomes are correlated. That fixed-effects generalized-least-squares approach analyzes the multiple outcomes jointly within a single model, and it can include covariates, such as duration of therapy or quality of trial, that may explain observed heterogeneity of results among the trials. Sometimes the covariates explain all the heterogeneity, and the fixed-effects regression model is appropriate. However, unexplained heterogeneity may often remain, even after taking into account known or suspected covariates. Because fixed-effects models do not make allowance for this remaining unexplained heterogeneity, the potential exists for bias in estimated coefficients, standard errors and p-values. We propose two random-effects approaches for the regression meta-analysis of multiple correlated outcomes. We compare their use with fixed-effects models and with separate-outcomes models in a meta-analysis of periodontal clinical trials. A simulation study shows the advantages of the random-effects approach. These methods also facilitate meta-analysis of trials that compare more than two treatments.

Clinical Trials as Topic↗
PubMed1998

Physical activity and benign prostatic hyperplasia.

BACKGROUND: Benign prostatic hyperplasia (BPH) leading to prostatic enlargement and lower urinary tract symptoms is highly prevalent among older men. Sympathetic nervous system activity, which is decreased by physical activity, is associated with increased prostatic smooth-muscle tone and prostatic symptoms. Therefore, we assessed whether physical activity leads to fewer lower urinary tract symptoms in the Health Professionals Follow-up Study. METHODS: We observed men who were aged 40 to 75 years at baseline in 1986 for subsequent incidence of surgery for BPH. The men were free of diagnosed cancer, including prostate cancer at baseline and during follow-up, had not had a radical prostatectomy, and provided data on physical activity. Cases were men who under-went BPH surgery between 1986 and 1994 (n = 1890) or, among those who did not have surgery, who scored 15 or more points of 35 (n = 1853) on 7 questions about lower urinary tract symptoms modified from the American Urological Association Symptom Index. Noncases were men who scored 7 points or less (n = 21745). Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated from multiple logistic regression models. RESULTS: After controlling for age, race or ethnicity, alcohol consumption, and smoking, physical activity was inversely related with total BPH (extreme quintiles: OR, 0.75; 95% CI, 0.67-0.85; P for trend, <.001), surgery for BPH (OR, 0.76; 95% CI, 0.64-0.90; P for trend, <.001), and symptomatic BPH (OR, 0.75; 95% CI, 0.64-0.87; P for trend, <.001). Walking, the most prevalent activity, was inversely related to BPH risk; men who walked 2 to 3 h/wk had a 25% lower risk of total BPH. CONCLUSION: Our results indicate that more physically active men have a lower frequency of lower urinary tract symptoms.

Adult↗
PubMed1998

A prospective study of physical activity and prostate cancer in male health professionals.

Because the role of exercise in prostate cancer is unclear, we examined the relationship between leisure time physical activity and risk of prostate cancer in the Health Professionals Follow-up Study, a prospective cohort study of male health professionals in the United States. In 1986, 47,542 men 40-75 years of age and free of cancer responded to a mailed questionnaire that included an assessment of physical activity. The reported average time per week spent on each of a variety of nonoccupational activities was multiplied by its typical energy expenditure requirements expressed in metabolic equivalents (METs) and summed to yield a total weekly MET-hour score. We also examined MET-hours from all vigorous activities, defined as those requiring energy expenditures of six or more METs, and nonvigorous activities. From 1986 until January 31, 1994, we identified 1362 incident cases of total prostate cancer (excluding stage A1), 419 advanced (extraprostatic) cases, and 200 metastatic cases. No relationship with total or advanced prostate cancer was evident for total, vigorous, and nonvigorous physical activity. For metastatic prostate cancer, we also found no linear trends for these activities, but did observe a significantly lower risk in the highest category of vigorous activity (multivariate relative risk = 0.46; 95% confidence interval = 0.24-0.89 for > 25 versus 0 MET-hours), controlling for age, vasectomy, history of diabetes, height, smoking, and dietary factors. This highest category included 15% of the population and reflects at least 3 h/week of participation in vigorous activities. Differences in disease surveillance according to activity level could not account for our findings. The results from this cohort indicate that physical activity is unlikely to influence the incidence of total prostate cancer appreciably; however, the suggestion of a lower risk of metastatic prostate cancer in men engaging in high levels of vigorous activities warrants further study.

Adult↗
PubMed1998

Frequent nut consumption and risk of coronary heart disease in women: prospective cohort study.

OBJECTIVE: To examine the relation between nut consumption and risk of coronary heart disease in a cohort of women from the Nurses' Health Study. DESIGN: Prospective cohort study. SETTING: Nurses' Health Study. SUBJECTS: 86 016 women from 34 to 59 years of age without previously diagnosed coronary heart disease, stroke, or cancer at baseline in 1980. MAIN OUTCOME MEASURES: Major coronary heart disease including non-fatal myocardial infarction and fatal coronary heart disease. RESULTS: 1255 major coronary disease events (861 cases of non-fatal myocardial infarction and 394 cases of fatal coronary heart disease) occurred during 14 years of follow up. After adjusting for age, smoking, and other known risk factors for coronary heart disease, women who ate more than five units of nuts (one unit equivalent to 1 oz of nuts) a week (frequent consumption) had a significantly lower risk of total coronary heart disease (relative risk 0.65, 95% confidence interval 0.47 to 0.89, P for trend=0.0009) than women who never ate nuts or who ate less than one unit a month (rare consumption). The magnitude of risk reduction was similar for both fatal coronary heart disease (0.61, 0.35 to 1.05, P for trend=0.007) and non-fatal myocardial infarction (0.68, 0.47 to 1.00, P for trend=0.04). Further adjustment for intakes of dietary fats, fibre, vegetables, and fruits did not alter these results. The inverse association persisted in subgroups stratified by levels of smoking,use of alcohol, use of multivitamin and vitamin E supplements, body mass index, exercise, and intake of vegetables or fruits. CONCLUSIONS: Frequent nut consumption was associated with a reduced risk of both fatal coronary heart disease and non-fatal myocardial infarction. These data, and those from other epidemiological and clinical studies, support a role for nuts in reducing the risk of coronary heart disease.

Adult↗
PubMed1998

Calcium channel blockers, cancer incidence, and cancer mortality in a cohort of U.S. women: the nurses' health study.

BACKGROUND: Some studies have suggested that the use of calcium channel blockers may increase the risk of cancer. A possible association of the use of calcium channel blockers with cancer incidence and cancer mortality was addressed using data from the Nurses' Health Study. METHODS: In this study, a total of 18,635 female nurses reported regularly taking at least 1 of 4 cardiovascular medications in 1988: diuretics, beta-blockers, calcium channel blockers, and/or angiotensin-converting enzyme (ACE) inhibitors. Cancer incidence and cancer deaths were ascertained until 1994. RESULTS: During 6 years of follow-up, 852 women were newly diagnosed with cancer and 335 women died of cancer. Women who reported the use of calcium channel blockers had no increased risk of newly diagnosed cancer compared with those taking other cardiovascular drugs (relative risk=1.02; 95% CI 0.83-1.26). The relative risk of dying from cancer associated with the self-reported use of calcium channel blockers was 1.25 (95% CI 0.91-1.72). Relative risks were adjusted for the following self-reported factors: age; weight; height; cholesterol level; systolic and diastolic blood pressure; smoking; alcohol intake; physical activity; menopausal status; postmenopausal hormone use; aspirin use; and history of diabetes, cancer, stroke, myocardial infarction, coronary artery bypass graft or percutaneous transluminal coronary angioplasty, angina, and hypertension. Regarding site specific cancer incidence and mortality, only lung cancer incidence was somewhat increased (RR=1.61; 95% CI 0.88-2.96). CONCLUSIONS: These data suggest no important increase in overall cancer incidence or cancer mortality related to the self-reported use of calcium channel blockers.

Adrenergic beta-Antagonists↗
PubMed1998

Restriction as a method for reducing bias in the estimation of direct effects.

The direct effect of a treatment on some outcome is that part of the treatment's effect not referred through a specified covariate intermediate on the pathway between treatment and outcome. Such direct effects are often of primary interest in a data analysis. Unfortunately, standard methods of analysis (for example, stratification or modelling) do not, in general, produce consistent estimates of direct effects whether or not the covariate is 'controlled'. Robins and co-authors have proposed two methods for estimation of direct effects applicable when reliable information is available on the covariate. We propose a third approach for reducing bias: data restriction. By restricting the analysis to strata of the data in which the effect of treatment on the covariate is small, we can (under certain assumptions) reduce bias in estimating treatment's direct effect. We discuss these points with reference to difference and ratio measures of treatment effect. The approach will sometimes be applicable even with an unmeasured or poorly measured covariate. We illustrate these points with data from an observational study of the effect of hormone replacement therapy on breast cancer.

Bias↗
PubMed1998

Multivitamin use, folate, and colon cancer in women in the Nurses' Health Study.

BACKGROUND: High intake of folate may reduce risk for colon cancer, but the dosage and duration relations and the impact of dietary compared with supplementary sources are not well understood. OBJECTIVE: To evaluate the relation between folate intake and incidence of colon cancer. DESIGN: Prospective cohort study. SETTING: 88,756 women from the Nurses' Health Study who were free of cancer in 1980 and provided updated assessments of diet, including multivitamin supplement use, from 1980 to 1994. PATIENTS: 442 women with new cases of colon cancer. MEASUREMENTS: Multivariate relative risk (RR) and 95% CIs for colon cancer in relation to energy-adjusted folate intake. RESULTS: Higher energy-adjusted folate intake in 1980 was related to a lower risk for colon cancer (RR, 0.69 [95% CI, 0.52 to 0.93] for intake > 400 microg/d compared with intake < or = 200 microg/d) after controlling for age; family history of colorectal cancer; aspirin use; smoking; body mass; physical activity; and intakes of red meat, alcohol, methionine, and fiber. When intake of vitamins A, C, D, and E and intake of calcium were also controlled for, results were similar. Women who used multivitamins containing folic acid had no benefit with respect to colon cancer after 4 years of use (RR, 1.02) and had only nonsignificant risk reductions after 5 to 9 (RR, 0.83) or 10 to 14 years of use (RR, 0.80). After 15 years of use, however, risk was markedly lower (RR, 0.25 [CI, 0.13 to 0.51]), representing 15 instead of 68 new cases of colon cancer per 10,000 women 55 to 69 years of age. Folate from dietary sources alone was related to a modest reduction in risk for colon cancer, and the benefit of long-term multivitamin use was present across all levels of dietary intakes. CONCLUSIONS: Long-term use of multivitamins may substantially reduce risk for colon cancer. This effect may be related to the folic acid contained in multivitamins.

Adult↗
PubMed1998

Plasma sex steroid hormone levels and risk of breast cancer in postmenopausal women.

BACKGROUND: A positive relationship has generally been observed between plasma estrogen levels and breast cancer risk in postmenopausal women, but most of these studies have been small and few have evaluated specific estrogen fractions (such as percent bioavailable estradiol). In addition, few studies have evaluated plasma androgen levels in relation to breast cancer risk, and their results have been inconsistent. We prospectively evaluated relationships between sex steroid hormone levels in plasma and risk of breast cancer in postmenopausal women by use of a case-control study nested within the Nurses' Health Study. METHODS: Blood samples were collected during the period from 1989 through 1990. Among postmenopausal women not using hormone replacement therapy at blood collection (n = 11,169 women), 156 women were diagnosed with breast cancer after blood collection but before June 1, 1994. Two control subjects were selected per case subject and matched with respect to age, menopausal status, month and time of day of blood collection, and fasting status at the time of blood collection. RESULTS: From comparisons of highest and lowest (reference) quartiles, we observed statistically significant positive associations with risk of breast cancer for circulating levels of estradiol (multivariate relative risk [RR] = 1.91; 95% confidence interval [CI] = 1.06-3.46), estrone (multivariate RR = 1.96; 95% CI = 1.05-3.65), estrone sulfate (multivariate RR = 2.25; 95% CI = 1.23-4.12), and dehydroepiandrosterone sulfate (multivariate RR = 2.15; 95% CI = 1.11-4.17). We found no substantial associations with percent free or percent bioavailable estradiol, androstenedione, testosterone, or dehydroepiandrosterone. The positive relationships were substantially stronger among women with no previous hormone replacement therapy. CONCLUSION: Our data, in conjunction with past epidemiologic and animal studies, provide strong evidence for a causal relationship between postmenopausal estrogen levels and the risk of breast cancer.

Adult↗
PubMed1998

Physical activity and breast cancer risk in a cohort of young women.

BACKGROUND: Increased physical activity has been hypothesized to be a means of breast cancer prevention. We examined the associations between physical activity at two different times in life and breast cancer risk. METHODS: We analyzed data from the Nurses' Health Study II, a prospective study of women aged 25-42 years in 1989. On the baseline survey, women were asked, "While in high school and between the ages 18 and 22 years, how often did you participate in strenuous physical activity at least twice a week?" We averaged answers to these two questions to develop a measure of late adolescent activity. Women were also asked at baseline to report the number of hours per week they currently spent in different nonoccupational activities. During 6 years of follow-up, we identified 372 cases of invasive breast cancer. Data were analyzed by use of multivariate pooled logistic regression to produce relative risk (RR) and confidence intervals (CIs) of being diagnosed with the disease. RESULTS: Women who were more active in late adolescence were not at reduced risk of breast cancer compared with less active women. For those women who reported engaging in strenuous activity at least twice per week for 10-12 months per year in late adolescence, the RR of cancer, compared with those who never engaged in such activity, was 1.1 (95% CI = 0.8-1.6). Similarly, higher levels of recent nonoccupational physical activity were not associated with reduced risk of breast cancer (RR for > or = 7 hours of activity/week relative to < 1 hour/week = 1.1; 95% CI = 0.8-1.5). CONCLUSION: Our findings do not support a link between physical activity, in late adolescence or in the recent past, and breast cancer risk among young adult women.

Adolescent↗
PubMed1998

Retrospective analysis of birth weight and prostate cancer in the Health Professionals Follow-up Study.

The authors retrospectively evaluated the relation between birth weight and prostate cancer (1986-1994) among 21,140 men of the Health Professionals Follow-up Study who reported in 1994 their weight at birth. No relation between birth weight and prostate cancer (n=545) was observed in multivariate logistic models. For high stage/grade tumors (n=213), compared with birth weights <7.0 lbs (<3,175 g), the relative risks were 1.20 (95% confidence interval (CI) 0.79-1.83) for 8.5-9.9 lbs (3,855.6-4,490.6 g) and 1.30 (95% CI 0.80-2.10) for > or = 10 lbs (> or = 4,536 g). These findings do not support an overall association between birth weight and prostate cancer incidence, but the possibility of a modest positive association between birth weight and high stage/grade prostatic cancer cannot be excluded.

Adult↗
PubMed1998

Relationship between estrogen levels, use of hormone replacement therapy, and breast cancer.

We sought to determine the strength of the evidence suggesting that estrogen and postmenopausal replacement hormones play a role in the development of breast cancer. We reviewed the existing English language literature in MEDLINE on hormones and breast cancer, including reports on cell proliferation and endogenous hormone levels, as well as epidemiologic studies of the relationship between the use of postmenopausal hormones and the risk of breast cancer in women. A factor that increases the probability that cancer will develop in an individual has been defined as a cancer cause. The Hill criteria for demonstrating a link between environmental factors and disease were used to review the evidence for a causal relationship between female hormones and breast cancer. We found evidence of a causal relationship between these hormones and breast cancer, based on the following criteria: consistency, dose-response pattern, biologic plausibility, temporality, strength of association, and coherence. The magnitude of the increase in breast cancer risk per year of hormone use is comparable to that associated with delaying menopause by a year. The positive relationship between endogenous hormone levels in postmenopausal women and risk of breast cancer supports a biologic mechanism for the relationship between use of hormones and increased risk of this disease. The finding that the increase in risk of breast cancer associated with increasing duration of hormone use does not vary substantially across studies offers further evidence for a causal relationship. We conclude that existing evidence supports a causal relationship between use of estrogens and progestins, levels of endogenous estrogens, and breast cancer incidence in postmenopausal women. Hormones may act to promote the late stages of carcinogenesis among postmenopausal women and to facilitate the proliferation of malignant cells. Strategies that do not cause breast cancer are urgently needed for the relief of menopausal symptoms and the long-term prevention of osteoporosis and heart disease.

Aged↗
PubMed1998

Circulating concentrations of insulin-like growth factor-I and risk of breast cancer.

BACKGROUND: Insulin-like growth factor (IGF)-I, a mitogenic and antiapoptotic peptide, can affect the proliferation of breast epithelial cells, and is thought to have a role in breast cancer. We hypothesised that high circulating IGF-I concentrations would be associated with an increased risk of breast cancer. METHODS: We carried out a nested case-control study within the prospective Nurses' Health Study cohort. Plasma concentrations of IGF-I and IGF binding protein 3 (IGFBP-3) were measured in blood samples collected in 1989-90. We identified 397 women who had a diagnosis of breast cancer after this date and 620 age-matched controls. IGF-I concentrations were compared by logistic regression with adjustment for other breast-cancer risk factors. FINDINGS: There was no association between IGF-I concentrations and breast-cancer risk among the whole study group. In postmenopausal women there was no association between IGF-I concentrations and breast-cancer risk (top vs bottom quintile of IGF-I, relative risk 0.85 [95% CI 0.53-1.39]). The relative risk of breast cancer among premenopausal women by IGF-I concentration (top vs bottom tertile) was 2.33 (1.06-5.16; p for trend 0.08). Among premenopausal women less than 50 years old at the time of blood collection, the relative risk was 4.58 (1.75-12.0; p for trend 0.02). After further adjustment for plasma IGFBP-3 concentrations these relative risks were 2.88 and 7.28, respectively. INTERPRETATION: A positive relation between circulating IGF-I concentration and risk of breast cancer was found among premenopausal but not postmenopausal women. Plasma IGF-I concentrations may be useful in the identification of women at high risk of breast cancer and in the development of risk reduction strategies. Additional larger studies of this association among premenopausal women are needed to provide more precise estimates of effect.

Breast Neoplasms↗
PubMed1998

Postmenopausal hormone use and risk for colorectal cancer and adenoma.

BACKGROUND: Accumulating evidence suggests that postmenopausal hormone use may decrease the risk for colorectal cancer. OBJECTIVE: To examine the relation of postmenopausal hormone therapy to colorectal adenoma and cancer. DESIGN: Prospective cohort and nested case-control studies. SETTING: Nurses' Health Study, a study of registered nurses recruited from 11 U.S. states. PARTICIPANTS: 59 002 postmenopausal participants in the Nurses' Health Study. MEASUREMENTS: Self-reported data on hormone use and cases of distal colorectal adenoma and colorectal cancer obtained from biennial questionnaires completed from 1980 to 1994. Cases of colorectal adenoma and cancer were confirmed by medical record review. RESULTS: 470 women developed colorectal cancer, and 838 developed distal colorectal adenomas. Current use of postmenopausal hormones was associated with a decreased risk for colorectal cancer (relative risk [RR], 0.65 [95% CI, 0.50 to 0.83]). This association was attenuated in past users (RR, 0.84 [CI, 0.67 to 1.05]) and disappeared 5 years after hormone use was discontinued (RR, 0.92 [CI, 0.70 to 1.21]). Longer duration of current use did not afford greater protection (RR with > or =5 years of use, 0.72 [CI, 0.53 to 0.96]). Even after exclusion of women who reported having screening sigmoidoscopy, the relative risk for colorectal cancer seen with current hormone use was 0.64 (CI, 0.49 to 0.82). This suggests that the apparent protection is unlikely to be due to more intensive screening among hormone users. Current users also had a lower risk for large (> or =1 cm) adenomas than did women who had never used hormones (RR, 0.74 [CI, 0.55 to 0.99]), although no overall material association was seen between colorectal adenoma and current hormone use (RR, 0.91 [CI,0.77 to 1.08]). CONCLUSIONS: The risk for colorectal cancer was decreased among women currently receiving postmenopausal hormone therapy, but the apparent reduction substantially diminished upon cessation of therapy. Hormone use was inversely associated with large colorectal adenomas but not small ones.

Adenoma↗
PubMed1998

Menstrual cycle characteristics and history of ovulatory infertility in relation to breast cancer risk in a large cohort of US women.

Menstrual cycle characteristics and ovulatory infertility were evaluated in relation to breast cancer risk among 116,678 women in the Nurses' Health Study II, a prospective cohort study of female registered nurses who were aged 25-42 years and living in 14 US states at enrollment in 1989. During 396,299 person-years of follow-up between return of the baseline questionnaire and June 1993, 251 cases of breast cancer were identified in this cohort. The multivariate relative risk (RR) associated with age at menarche > 13 years compared with age < or = 12 years was 0.66 (95% confidence interval (CI) 0.44-0.99). Short and long menstrual cycle lengths at ages 18-22 years were associated with reduced risk. Compared with menstrual cycle length 26-31 days, the multivariate relative risks (95% CIs) for more extreme cycle lengths were: < 26 days, 0.50 (0.25-0.98); 32-39 days, 0.81 (0.51-1.28); and > 39 days or too irregular for estimation of a usual cycle length, 0.41 (0.18-0.94). The multivariate relative risk associated with a history of ovulatory infertility, compared with no such history, was 0.41 (95% CI 0.18-0.93). These results are consistent with the hypothesis that reduced exposure to ovulatory menstrual cycles provides a protective effect against breast cancer.

Adult↗