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Biomedical subjects

W C Willett

Publications and source records attributed to W C Willett.

At least 37 records · Page 2Linked to original sources
PubMed2002

Stress and suicide in the Nurses' Health Study.

STUDY OBJECTIVES: Although stress is thought to be a risk factor for suicide, most research has been retrospective or has focused on attempted suicides or suicide ideation. This study examined prospectively the associations between self perceived stress, diazepam use, and death from suicide among adult women. DESIGN: A cohort study was conducted with 14 years of follow up. Stress at home and at work were assessed by questionnaire and scored on a four point scale: minimal, light, moderate, or severe. SETTING: Eleven states within the United States. PARTICIPANTS: Female nurses (n=94 110) who were 36 to 61 years of age when they answered questions on stress and diazepam use in 1982. RESULTS: During 1 272 000 person years of observation 73 suicides were identified. After adjustment for age, smoking, coffee consumption, alcohol intake, and marital status, the relation between self reported stress and suicide remained U shaped. Compared with the light home and work stress categories, which had the lowest incidences of suicide, risks were increased among women reporting either severe (relative risk (RR) = 3.7, 95% confidence intervals (CI) 1.7 to 8.3) or minimal (RR=2.1, 95% CI 1.0 to 4.5) home stress and either severe (RR=1.9, 95% CI 0.8 to 4.7) or minimal (RR=2.4, 95% CI 0.9 to 6.1) work stress. When responses to home and work stress were combined, there was an almost fivefold increase in risk of suicide among women in the high stress category. Risk of suicide was over eightfold among women reporting high stress or diazepam use compared with those reporting low stress and no diazepam use. CONCLUSIONS: The relation between self reported stress and suicide seems to be U shaped among adult women. The excess risk for those reporting minimal stress may reflect denial or undiagnosed depression or an association with some other unmeasured risk factor for suicide.

Adult↗
PubMed2001

Long or highly irregular menstrual cycles as a marker for risk of type 2 diabetes mellitus.

CONTEXT: Although oligomenorrhea has been associated cross-sectionally with insulin resistance and glucose intolerance, it is not known whether oligomenorrhea is a marker for increased future risk of type 2 diabetes mellitus (DM). OBJECTIVE: To prospectively assess risk of type 2 DM in women with a history of long or highly irregular menstrual cycles. DESIGN AND SETTING: The Nurses' Health Study II, a prospective observational cohort study. PARTICIPANTS: A total of 101 073 women who had no prior history of DM and who reported their usual menstrual cycle pattern at age 18 to 22 years on the baseline (1989) questionnaire. MAIN OUTCOME MEASURE: Incident reports of DM, with follow-up through 1997, compared among women categorized by menstrual cycle length (5 categories). RESULTS: During 564 333 person-years of follow-up, there were 507 cases of type 2 DM. Compared with women with a usual cycle length of 26 to 31 days (referent category) at age 18 to 22 years, the relative risk (RR) of type 2 DM among women with a menstrual cycle length that was 40 days or more or was too irregular to estimate was 2.08 (95% confidence interval [CI], 1.62-2.66), adjusting for body mass index at age 18 years and several other potential confounding variables. The RR of type 2 DM associated with long or highly irregular menstrual cycles was greater in obese women, but was also increased in nonobese women (at body mass indexes at age 18 years of <25, 25-29, and >/=30 kg/m, RRs were 1.67 [95% CI, 1.14-2.45], 1.74 [95% CI, 1.07-2.82], and 3.86 [95% CI, 2.33-6.38], respectively). CONCLUSION: Women with long or highly irregular menstrual cycles have a significantly increased risk for developing type 2 DM that is not completely explained by obesity.

Adult↗
PubMed2001

Risk of ovarian carcinoma and consumption of vitamins A, C, and E and specific carotenoids: a prospective analysis.

BACKGROUND: Antioxidant vitamins may decrease risk of cancer by limiting oxidative DNA damage leading to cancer initiation. Few prospective studies have assessed relations between antioxidant vitamins and ovarian carcinoma. METHODS: The authors prospectively assessed consumption of vitamins A, C, and E and specific carotenoids, as well as fruit and vegetable intake, in relation to ovarian carcinoma risk among 80,326 participants in the Nurses' Health Study who had no history of cancer other than nonmelanoma skin carcinoma. Women reported on known and suspected ovarian carcinoma risk factors including reproductive factors, smoking, and use of vitamin supplements on biennial mailed questionnaires from 1976 to 1996. Food frequency questionnaires were included in 1980, 1984, 1986, and 1990. The authors confirmed 301 incident cases of invasive epithelial ovarian carcinoma during 16 years of dietary follow-up (1980-1996). Pooled logistic regression was used to control for age, oral contraceptive use, body mass index, smoking history, parity, and tubal ligation. RESULTS: The authors observed no association between ovarian carcinoma risk and antioxidant vitamin consumption from foods, or foods and supplements together. The multivariate relative risks (95% confidence intervals [CIs]) for ovarian carcinoma among women in the highest versus lowest quintile of intake were 1.04 (95% CI, 0.72-1.51) for vitamin A from foods and supplements; 1.01 (95% CI, 0.69-1.47) for vitamin C; 0.88 (95% CI, 0.61-1.27) for vitamin E; and 1.10 (95% CI, 0.76-1.59) for beta-carotene. Among users of vitamin supplements, the authors found no evidence of an association between dose or duration of any specific vitamin and ovarian carcinoma risk, although the authors had limited power to assess these relations. No specific fruits or vegetables were associated significantly with ovarian carcinoma risk. The authors found no association between ovarian carcinoma and consumption of total fruits or vegetables, or specific subgroups including cruciferous vegetables, green leafy vegetables, legumes, or citrus fruits. Women who consumed at least 2.5 total servings of fruits and vegetables as adolescents had a 46% reduction in ovarian carcinoma risk (relative risk, 0.54, 95% CI, 0.29-1.03; P value for trend 0.04). CONCLUSIONS: These data do not support an important relation between consumption of antioxidant vitamins from foods or supplements, or intake of fruits and vegetables, and incidence of ovarian carcinoma in this cohort. However, modest associations cannot be excluded, and the authors' finding of an inverse association for total fruit and vegetable intake during adolescence raises the possibility that the pertinent exposure period may be much earlier than formerly anticipated.

Adolescent↗
PubMed2001

Rotating night shifts and risk of breast cancer in women participating in the nurses' health study.

BACKGROUND: Melatonin shows potential oncostatic action, and light exposure during night suppresses melatonin production. There is little information, however, about the direct effect of night work on the risk of cancer. We investigated the effect of night work in breast cancer. METHODS: We examined the relationship between breast cancer and working on rotating night shifts during 10 years of follow-up in 78 562 women from the Nurses' Health Study. Information was ascertained in 1988 about the total number of years during which the nurses had worked rotating night shifts with at least three nights per month. From June 1988 through May 1998, we documented 2441 incident breast cancer cases. Logistic regression models were used to calculate relative risks (RRs) and 95% confidence intervals (CIs), adjusted for confounding variables and breast cancer risk factors. All statistical tests were two-sided. RESULTS: We observed a moderate increase in breast cancer risk among the women who worked 1-14 years or 15-29 years on rotating night shifts (multivariate adjusted RR = 1.08 [95% CI = 0.99 to 1.18] and RR = 1.08 [95% CI = 0.90 to 1.30], respectively). The risk was further increased among women who worked 30 or more years on the night shift (RR = 1.36; 95% CI = 1.04 to 1.78). The test for trend was statistically significant (P =.02). CONCLUSIONS: Women who work on rotating night shifts with at least three nights per month, in addition to days and evenings in that month, appear to have a moderately increased risk of breast cancer after extended periods of working rotating night shifts.

Adult↗
PubMed2001

Diet, lifestyle, and the risk of type 2 diabetes mellitus in women.

BACKGROUND: Previous studies have examined individual dietary and lifestyle factors in relation to type 2 diabetes, but the combined effects of these factors are largely unknown. METHODS: We followed 84,941 female nurses from 1980 to 1996; these women were free of diagnosed cardiovascular disease, diabetes, and cancer at base line. Information about their diet and lifestyle was updated periodically. A low-risk group was defined according to a combination of five variables: a bodymass index (the weight in kilograms divided by the square of the height in meters) of less than 25; a diet high in cereal fiber and polyunsaturated fat and low in trans fat and glycemic load (which reflects the effect of diet on the blood glucose level); engagement in moderate-to-vigorous physical activity for at least half an hour per day; no current smoking; and the consumption of an average of at least half a drink of an alcoholic beverage per day. RESULTS: During 16 years of follow-up, we documented 3300 new cases of type 2 diabetes. Overweight or obesity was the single most important predictor of diabetes. Lack of exercise, a poor diet, current smoking, and abstinence from alcohol use were all associated with a significantly increased risk of diabetes, even after adjustment for the body-mass index. As compared with the rest of the cohort, women in the low-risk group (3.4 percent of the women) had a relative risk of diabetes of 0.09 (95 percent confidence interval, 0.05 to 0.17). A total of 91 percent of the cases of diabetes in this cohort (95 percent confidence interval, 83 to 95) could be attributed to habits and forms of behavior that did not conform to the low-risk pattern. CONCLUSIONS: Our findings support the hypothesis that the vast majority of cases of type 2 diabetes could be prevented by the adoption of a healthier lifestyle.

Adult↗
PubMed2001

The impact of diabetes mellitus on mortality from all causes and coronary heart disease in women: 20 years of follow-up.

BACKGROUND: Few data are available on the long-term impact of type 2 diabetes mellitus on total mortality and fatal coronary heart disease (CHD) in women. METHODS: We examined prospectively the impact of type 2 diabetes and history of prior CHD on mortality from all causes and CHD among 121 046 women aged 30 to 55 years with type 2 diabetes in the Nurses' Health Study who were followed up for 20 years from 1976 to 1996. RESULTS: During 20 years of follow-up, we documented 8464 deaths from all causes, including 1239 fatal CHD events. Compared with women with no diabetes or CHD at baseline, age-adjusted relative risks (RRs) of overall mortality were 3.39 (95% confidence interval [CI], 3.08-3.73) for women with a history of diabetes and no CHD at baseline, 3.00 (95% CI, 2.50-3.60) for women with a history of CHD and no diabetes at baseline, and 6.84 (95% CI, 4.71-9.95) for women with both conditions at baseline. The corresponding age-adjusted RRs of fatal CHD across these 4 groups were 1.0, 8.70, 10.6, and 25.8, respectively. Multivariate adjustment for body mass index and other coronary risk factors only modestly attenuated the RRs. Compared with nondiabetic persons, the multivariate RRs of fatal CHD across categories of diabetes duration (< or =5, 6-10, 11-15, 16-25, >25 years) were 2.75, 3.63, 5.51, 6.38, and 11.9 (P< .001 for trend), respectively. The combination of prior CHD and a long duration of clinical diabetes (ie, >15 years) was associated with a 30-fold (95% CI, 20.7-43.5) increased risk of fatal CHD. CONCLUSIONS: Our data indicate that among women, history of diabetes is associated with dramatically increased risks of death from all causes and fatal CHD. The combination of diabetes and prior CHD identifies particularly high-risk women.

Adult↗
PubMed2001

Intakes of carotenoids, vitamin C, and vitamin E and MS risk among two large cohorts of women.

BACKGROUND: Antioxidant nutrients may reduce the risk of MS. In a recent case-control study, vitamin C intake was significantly inversely associated with MS risk among women. However, no prospective data are available. OBJECTIVE: To examine prospectively the associations of intakes of carotenoids, vitamin C, and vitamin E with the risk of MS among women. METHODS: The authors documented the occurrence of definite and probable MS within two large cohorts of women who completed detailed and validated semiquantitative food frequency questionnaires. One cohort (Nurses' Health Study) comprised 81,683 women aged 38 to 63 years in 1984, who were followed for 12 years; the other (Nurses' Health Study II) comprised 95,056 women aged 27 to 44 years in 1991, who were followed for 6 years. RESULTS: The authors documented a total of 214 cases of MS. After adjustments for age, latitude of birthplace, pack-years of smoking, and total energy intake, the pooled multivariate relative risks (95% CIs) comparing women in the highest quintile with those in the lowest quintile were 1.1 (0.7 to 1.7) for alpha-carotene, 1.1 (0.7 to 1.6) for beta-carotene, 1.4 (0.8 to 2.2) for beta-cryptoxanthin, 1.0 (0.6 to 1.5) for lycopene, 1.0 (0.7 to 1.6) for lutein/zeaxanthin, 1.4 (0.9 to 2.1) for total vitamin C, 1.3 (0.9 to 2.0) for dietary vitamin C, 0.8 (0.6 to 1.3) for total vitamin E, and 0.9 (0.6 to 1.4) for dietary vitamin E. The authors found no associations between intakes of fruits and vegetables and risk of MS. Use of vitamin C, vitamin E, and multivitamin supplements was also unrelated to risk of MS. CONCLUSIONS: These findings do not support hypotheses relating higher intakes of dietary carotenoids, vitamin C, and vitamin E to reduced risk of MS in women.

Adult↗
PubMed2001

Physical activity and television watching in relation to risk for type 2 diabetes mellitus in men.

BACKGROUND: Television (TV) watching, a major sedentary behavior in the United States, has been associated with obesity. We hypothesized that prolonged TV watching may increase risk for type 2 diabetes. METHODS: In 1986, 37 918 men aged 40 to 75 years and free of diabetes, cardiovascular disease, and cancer completed a detailed physical activity questionnaire. Starting from 1988, participants reported their average weekly time spent watching TV on biennial questionnaires. RESULTS: A total of 1058 cases of type 2 diabetes were diagnosed during 10 years (347 040 person-years) of follow-up. After adjustment for age, smoking, alcohol use, and other covariates, the relative risks (RRs) for type 2 diabetes across increasing quintiles of metabolic equivalent hours (MET-hours) per week were 1.00, 0.78, 0.65, 0.58, and 0.51 (P for trend, <.001). Time spent watching TV was significantly associated with higher risk for diabetes. After adjustment for age, smoking, physical activity levels, and other covariates, the RRs of diabetes across categories of average hours spent watching TV per week (0-1, 2-10, 11-20, 21-40, and >40) were 1.00, 1.66, 1.64, 2.16, and 2.87, respectively (P for trend, <.001). This association was somewhat attenuated after adjustment for body mass index, but a significant positive gradient persisted (RR comparing extreme categories, 2.31; P for trend,.01). CONCLUSIONS: Increasing physical activity is associated with a significant reduction in risk for diabetes, whereas a sedentary lifestyle indicated by prolonged TV watching is directly related to risk. Our findings suggest the importance of reducing sedentary behavior in the prevention of type 2 diabetes.

Adult↗
PubMed2001

Prospective study of recreational physical activity and ovarian cancer.

BACKGROUND: It has been hypothesized that physical activity may reduce the risk of ovarian cancer by decreasing estrogen levels, reducing body fat, and reducing the frequency of ovulation. Epidemiologic studies of this relationship have obtained inconsistent results. The only prospective study to date reported a positive association between frequent vigorous exercise and ovarian cancer risk. We further evaluated this relationship in the Nurses' Health Study cohort. METHODS: Participation in recreational physical activity was assessed by questionnaire in 1980, 1982, 1986, 1988, 1992, and 1994, with questions assessing exercise frequency, duration, and intensity. Results were adjusted for age, parity, oral contraceptive use, tubal ligation, and other risk factors for ovarian cancer. All statistical tests were two-sided. RESULTS: During a 16-year follow-up (from 1980 to 1996), 1.2 million person-years were accrued by 92 825 cohort members, and 377 cases of epithelial ovarian cancer were confirmed. The relative risk (RR) of ovarian cancer for women engaging in recreational physical activity for 7 hours or more per week compared with those reporting less than 1 hour per week was 0.80 (95% confidence interval [CI] = 0.49 to 1.32; P(trend) =.59). When both the frequency and intensity of activity were taken into account, activity level was also not associated with a reduced risk of ovarian cancer. Compared with inactive women, participants reporting high activity in terms of metabolic equivalent task hours (MET hours) were at greater risk of ovarian cancer (RR for 20 to <30 MET hours/week = 1.84 [95% CI = 1.12 to 3.02]; RR for >30 MET hours/week = 1.27 [95% CI = 0.75 to 2.14]). CONCLUSIONS: Overall, results did not suggest an inverse association between recreational physical activity and ovarian cancer. The possibility of a modest increase in risk with frequent vigorous activity requires further investigation.

Adult↗
PubMed2001

The effect of fruit and vegetable intake on risk for coronary heart disease.

BACKGROUND: Many constituents of fruits and vegetables may reduce the risk for coronary heart disease, but data on the relationship between fruit and vegetable consumption and risk for coronary heart disease are sparse. OBJECTIVE: To evaluate the association of fruit and vegetable consumption with risk for coronary heart disease. DESIGN: Prospective cohort study. SETTING: The Nurses' Health Study and the Health Professionals' Follow-Up Study. PARTICIPANTS: 84 251 women 34 to 59 years of age who were followed for 14 years and 42 148 men 40 to 75 years who were followed for 8 years. All were free of diagnosed cardiovascular disease, cancer, and diabetes at baseline. MEASUREMENTS: The main outcome measure was incidence of nonfatal myocardial infarction or fatal coronary heart disease (1127 cases in women and 1063 cases in men). Diet was assessed by using food-frequency questionnaires. RESULTS: After adjustment for standard cardiovascular risk factors, persons in the highest quintile of fruit and vegetable intake had a relative risk for coronary heart disease of 0.80 (95% CI, 0.69 to 0.93) compared with those in the lowest quintile of intake. Each 1-serving/d increase in intake of fruits or vegetables was associated with a 4% lower risk for coronary heart disease (relative risk, 0.96 [CI, 0.94 to 0.99]; P = 0.01, test for trend). Green leafy vegetables (relative risk with 1-serving/d increase, 0.77 [CI, 0.64 to 0.93]), and vitamin C-rich fruits and vegetables (relative risk with 1-serving/d increase, 0.94 [CI, 0.88 to 0.99]) contributed most to the apparent protective effect of total fruit and vegetable intake. CONCLUSIONS: Consumption of fruits and vegetables, particularly green leafy vegetables and vitamin C-rich fruits and vegetables, appears to have a protective effect against coronary heart disease.

Adult↗
PubMed2001

Types of dietary fat and breast cancer: a pooled analysis of cohort studies.

Recently, there has been interest in whether intakes of specific types of fat are associated with breast cancer risk independently of other types of fat, but results have been inconsistent. We identified 8 prospective studies that met predefined criteria and analyzed their primary data using a standardized approach. Holding total energy intake constant, we calculated relative risks for increments of 5% of energy for each type of fat compared with an equivalent amount of energy from carbohydrates or from other types of fat. We combined study-specific relative risks using a random effects model. In the pooled database, 7,329 incident invasive breast cancer cases occurred among 351,821 women. The pooled relative risks (95% confidence intervals [CI]) for an increment of 5% of energy were 1.09 (1.00-1.19) for saturated, 0.93 (0.84-1.03) for monounsaturated and 1.05 (0.96-1.16) for polyunsaturated fat compared with equivalent energy intake from carbohydrates. For a 5% of energy increment, the relative risks were 1.18 (95% CI 0.99-1.42) for substituting saturated for monounsaturated fat, 0.98 (95% CI 0.85-1.12) for substituting saturated for polyunsaturated fat and 0.87 (95% CI 0.73-1.02) for substituting monounsaturated for polyunsaturated fat. No associations were observed for animal or vegetable fat intakes. These associations were not modified by menopausal status. These data are suggestive of only a weak positive association with substitution of saturated fat for carbohydrate consumption; none of the other types of fat examined was significantly associated with breast cancer risk relative to an equivalent reduction in carbohydrate consumption.

Breast Neoplasms↗
PubMed2001

Vitamin supplement use and the risk of non-Hodgkin's lymphoma among women and men.

The authors examined use of individual supplements of vitamins A, C, and E only and multivitamins in relation to risk of non-Hodgkin's lymphoma in prospective cohorts of 88,410 women in the Nurses' Health Study (1980-1996), with 261 incident cases during 16 years of follow-up, and of 47,336 men in the Health Professionals Follow-Up Study (1986-1996), with 111 incident cases during 10 years of follow-up. Multivitamin use was associated with a higher risk of non-Hodgkin's lymphoma among women but not among men; the multivariate relative risks for long-term duration (10 or more years) were 1.48 (95% confidence interval (CI): 1.01, 2.16) for women and 0.85 (95% CI: 0.45, 1.58) for men. The pooled multivariate relative risk from the two cohorts was 1.18 (95% CI: 0.70, 2.02). Use of individual supplements of vitamins A, C, and E only was not associated with risk among men. An increased risk associated with the use of individual supplements of vitamins A, C, and E only among women appeared to be secondary to the use of multivitamins by the same persons. Because an elevated risk among multivitamin users was not observed consistently in the two cohorts and the pooled data were not significant, the elevated risk among women may be the result of chance.

Adult↗
PubMed2001

Fracture history and risk of breast and endometrial cancer.

Fractures in postmenopausal women may serve as a surrogate measure of bone density, reflecting long-term lower estrogen levels, and lower estrogen levels appear to be inversely associated with breast and endometrial cancer. Breast cancer cases aged 50-79 years (n = 5,559) and endometrial cancer cases aged 40-79 years (n = 739) were enrolled in a US case-control study in 1992-1994 to evaluate the relation between fractures and risk of breast and endometrial cancer. Controls for the breast cancer analysis (n = 5,829) and the endometrial cancer analysis (n = 2,334) were randomly selected from population lists (driver's license and Medicare files). Information on fracture history and other risk factors was obtained by telephone interview. Compared with women without a fracture in the past 5 years, the odds ratios for women with a history of fracture were 0.80 (95% confidence interval (CI): 0.68, 0.94) for breast cancer and 0.59 (95% CI: 0.40, 0.89) for endometrial cancer. Height loss (> or =2.5 cm) and recent fracture history were associated with the lowest risk of breast cancer (odds ratio = 0.62, 95% CI: 0.46, 0.83) and endometrial cancer (odds ratio = 0.15, 95% CI: 0.05, 0.43). These data suggest that the endogenous hormonal factors associated with increased fracture risk are also related to decreased breast cancer risk and, more strongly, to endometrial cancer risk.

Adult↗
PubMed2001

Prospective study of cataract extraction and risk of coronary heart disease in women.

Oxidative damage to proteins in the human lens is believed to be important in the etiology of age-related cataract. Because free radical-mediated oxidative damage to lipoproteins may accelerate atherosclerosis, the authors hypothesized that the development of cataract might be a marker for such damage and therefore might be associated with future risk of coronary heart disease (CHD). The authors followed 60,657 women aged 45--63 years and without known coronary disease, stroke, or cancer in 1984. During 10 years of follow-up (674,283 person-years), the authors documented 887 incident cases of CHD and 2,322 deaths. After adjustment for age, smoking, and other coronary risk factors, cataract extraction was significantly associated with higher risk of CHD (relative risk (RR) = 1.88, 95% confidence interval (CI): 1.41, 2.50) for total CHD, 2.44 (95% CI: 1.54, 3.89) for fatal CHD, and 1.63 (95% CI: 1.14, 2.34) for nonfatal myocardial infarction). The positive association between cataract extraction and total CHD was stronger among women with a history of diabetes (RR = 2.80, 95% CI: 1.77, 4.42) than among those without reported diabetes (RR = 1.51, 95 percent CI: 1.04, 2.18). In multivariate analyses, cataract extraction was associated with significantly increased overall mortality (RR = 1.37, 95 percent CI: 1.13, 1.66), which was entirely explained by the increased mortality from cardiovascular disease (RR = 1.84, 95% CI: 1.29, 2.64). These findings are compatible with current hypotheses relating oxidative damage and tissue aging to the development of cataract and CHD.

Cataract↗
PubMed2001

Plasma organochlorine levels and the risk of breast cancer: an extended follow-up in the Nurses' Health Study.

The environmental organochlorines 2,2-bis(p-chlorophenyl)1,1,1,trichloroethane (DDT) and polychlorinated biphenyls (PCBs) have been implicated as potential causes of female breast cancer. We continued follow-up of our 1997 case-control study nested in the Nurses' Health Study cohort, adding 143 postmenopausal cases and controls to the original 238 pairs, and examining specific PCB congeners for the first time. We measured plasma levels of 2,2-bis(p-chlorophenyl)ethylene (DDE), the major metabolite of DDT, and PCBs prospectively, comparing women who were diagnosed with breast cancer between 1 month and 4 years after blood collection with control women in whom breast cancer did not develop. Median concentrations of lipid-adjusted DDE, total PCBs, and PCB numbers 118, 138, 153 and 180, assessed individually, were similar among the cases and controls. The multivariate relative risk of breast cancer for women in the highest quintile of exposure as compared with women in the lowest quintile was 0.82 for DDE (95% confidence interval [CI]: 0.49-1.37) and 0.84 for total PCBs (95% CI: 0.47-1.52), 0.69 for PCB 118 (95% CI: 0.39-1.22), 0.87 for PCB 138 (95% CI: 0.50-1.50), 0.83 for PCB 153 (95% CI: 0.47-1.48), and 0.98 for PCB 180 (95% CI: 0.55-1.75). Sub-group analyses were also performed. Overall, our results do not support the hypothesis that exposure to DDT and PCBs increases the risk of breast cancer.

Adult↗