California Teachers Study Cohort Research Articles

Risk factors for surgically removed fibroids in a large cohort of teachers

To describe reproductive and lifestyle correlates of surgically confirmed fibroids. Prospective cohort study. The California Teachers Study, an ongoing prospective study of more than 133,000 female teachers and school administrators identified through the California State Teachers Retirement System. California Teachers Study cohort members, reporting no previous history of fibroids, were ascertained prospectively for surgical diagnosis of fibroids using hospital patient discharge records. Multivariable Cox proportional hazards regression methods were used to assess the association of self-reported menstrual, reproductive, and lifestyle characteristics with fibroids, using ages at the start and end of follow-up (in months) to define time on study. Hazard rate ratios, presented as relative risks (RR) with 95% confidence intervals (CI), were estimated. The strongest risk factor we identified was African-American race/ethnicity, as compared to non-Latina white women. We observed a reduced risk of fibroids for postmenopausal women in comparison to premenopausal women, but use of hormone replacement therapies (regardless of formulation) were associated with an increased risk. Other risk factors included race, a family history of fibroids, being overweight, and drinking alcohol, Smoking and diabetes were associated with a decreased risk of fibroids. These observations provide a more detailed epidemiologic profile of women with surgically managed fibroids.

Dietary Patterns and Risk of Ovarian Cancer in the California Teachers Study Cohort

Previous studies have examined the association between individual foods or nutrients, but not overall diet, and ovarian cancer risk. To account for the clustering of foods in the diet, we investigated the association between dietary patterns and risk of ovarian cancer in the prospective California Teachers Study cohort. Of 97,292 eligible women who completed the baseline dietary assessment in 1995–1996, 311 women developed epithelial ovarian cancer on or before December 31, 2004. Based on principal components analysis, 5 major dietary patterns were identified and termed plant-based, high-protein/high-fat, high-carbohydrate, ethnic, and salad-and-wine. Multivariable Cox proportional hazards regression analysis was used to estimate associations between these dietary patterns and risk of incident ovarian cancer. Most of the dietary patterns were not significantly associated with ovarian cancer risk. However, women who followed a plant-based diet had higher risk; comparing those in the top quintile of plant-based food intake with those in the lowest quintile, the relative risk of ovarian cancer was 1.65 (95% confidence interval = 1.07–2.54; P trend = 0.03). Associations with the 5 dietary patterns did not vary by known ovarian cancer risk factors or other behavioral or sociodemographic characteristics. Overall, our results show no convincing associations between dietary patterns and ovarian cancer risk.

Incomplete pregnancy is not associated with breast cancer risk: the California Teachers Study

BackgroundEarly studies of incomplete pregnancy and development of breast cancer suggested that induced abortion might increase risk. Several large prospective studies, which eliminate recall bias, did not detect associations, but this relationship continues to be debated. Study DesignTo further inform this important question, we examined invasive breast cancer as it relates to incomplete pregnancy, including total number of induced abortions, age at first induced abortion and total number of miscarriages among women participating in the ongoing California Teachers Study (CTS) cohort. Incomplete pregnancy was self-reported on the CTS baseline questionnaire in 1995–1996. Incident breast cancers were ascertained in 3324 women through 2004 via linkage with the California Cancer Registry. ResultsUsing Cox multivariable regression, we found no statistically significant association between any measure of incomplete pregnancy and breast cancer risk among nulliparous or parous women. ConclusionThese results provide strong evidence that there is no relationship between incomplete pregnancy and breast cancer risk.

Dietary assessment in the California Teachers Study: reproducibility and validity.

To evaluate the reproducibility and validity of the food-frequency questionnaire (FFQ) used in the California Teachers Study (CTS) cohort and to use this data to quantify the effects of correcting nutrient-breast cancer relative risks for measurement error. One hundred and ninety five CTS cohort members participated in a 10-month dietary validation study that included four 24-h dietary recalls and pre- and post-study FFQs. Shrout-Fleiss intraclass correlations for reproducibility were computed. Under several standard assumptions concerning the correlations of errors in the FFQs and 24-h recalls, we calculated energy-adjusted deattenuated Pearson correlations for validity and tested for differences in validity according to a number of demographic and other risk factors. For each nutrient, we compared the performance of the FFQ versus the 24-h recalls, estimating the number of days of recalls that give equivalent information about true intake as does a single FFQ. Finally, the effects of adjustment for measurement error on risk estimates were evaluated in 44,423 postmenopausal cohort members, 1,544 of whom developed breast cancer during seven years of follow-up. Relative risks (RR) and confidence intervals (CI) were calculated using Cox proportional hazards with and without correction for measurement error. Reproducibility correlations for the nutrients ranged from 0.60 to 0.87. With a few exceptions, validity correlations were reasonably high (range: 0.55-0.85), including r = 0.74 for alcohol. Performance of the FFQ differed by age for percent of calories from fat and by body mass index and hormone therapy use for alcohol consumption. For most nutrients examined, our FFQ is comparable to two to six recalls for each subject in capturing true intake. In the measurement error-adjusted risk analyses, corrected RRs were within 13% of uncorrected values for all nutrients examined except for linoleic acid. For alcohol consumption the corrected RR (per 20 g/1,000 kcal/d) was 1.36 (95% CI: 1.03-1.51) compared to the uncorrected estimate of 1.25 (95% CI: 1.10-1.42). The FFQ dietary assessment used in the CTS is reproducible and valid for all nutrients except the unsaturated fatty acids. Correcting relative risk estimates for measurement error resulted in relatively small changes in the associations between the majority of nutrients and the risk of postmenopausal breast cancer.

Adenomyosis and endometriosis in the California Teachers Study

To evaluate the reproductive and lifestyle correlates of a surgically confirmed diagnosis of endometriosis or adenomyosis in a large prospective cohort. Collection of surgical diagnoses of endometriosis and adenomyosis during follow-up of women with no prior history of endometriosis and no prior surgery for adenomyosis. The California Teachers Study (CTS), an ongoing prospective study of female teachers and school administrators established from the rolls of the California State Teachers Retirement System. Women with surgical diagnoses of endometriosis and adenomyosis were identified from California statewide hospital patient discharge records for CTS cohort members with an intact uterus and no prior history of endometriosis. Women with an incident surgical diagnosis of endometriosis (n = 229) or adenomyosis (n = 961) were compared with disease-free women in the same age range (for endometriosis, n = 43,493; for adenomyosis, n = 79,495). None. Multivariable logistic regression methods were used to calculate prevalence odds ratios and associated 95% confidence intervals for the associations between self-reported menstrual and reproductive characteristics and either endometriosis or adenomyosis. Women surgically diagnosed with endometriosis were younger than those surgically diagnosed with adenomyosis. Factors statistically significantly associated with endometriosis were having a mother or sister with endometriosis and nulligravidity. Factors statistically significantly associated with adenomyosis were increasing parity, early menarche (<or=10 years of age), and short menstrual cycles (<or=24 days in length). Obese women also were more likely to have a surgical diagnosis of adenomyosis. These observations provide the first epidemiologic profile of women with a surgical diagnosis of adenomyosis and indicate that this profile differs from that of women with a surgical diagnosis of endometriosis. Our results also suggest that adenomyosis but not endometriosis is associated with increased endogenous exposure to estrogen.

Diet and Risk of Ovarian Cancer in the California Teachers Study Cohort

Dietary phytochemical compounds, including isoflavones and isothiocyanates, may inhibit cancer development but have not yet been examined in prospective epidemiologic studies of ovarian cancer. The authors have investigated the association between consumption of these and other nutrients and ovarian cancer risk in a prospective cohort study. Among 97,275 eligible women in the California Teachers Study cohort who completed the baseline dietary assessment in 1995-1996, 280 women developed invasive or borderline ovarian cancer by December 31, 2003. Multivariable Cox proportional hazards regression, with age as the timescale, was used to estimate relative risks and 95% confidence intervals; all statistical tests were two sided. Intake of isoflavones was associated with lower risk of ovarian cancer. Compared with the risk for women who consumed less than 1 mg of total isoflavones per day, the relative risk of ovarian cancer associated with consumption of more than 3 mg/day was 0.56 (95% confidence interval: 0.33, 0.96). Intake of isothiocyanates or foods high in isothiocyanates was not associated with ovarian cancer risk, nor was intake of macronutrients, antioxidant vitamins, or other micronutrients. Although dietary consumption of isoflavones may be associated with decreased ovarian cancer risk, most dietary factors are unlikely to play a major role in ovarian cancer development.

Wine and other alcohol consumption and risk of ovarian cancer in the California Teachers Study cohort

ObjectiveWhether alcohol consumption influences ovarian cancer risk is unclear. Therefore, we investigated the association between alcohol intake at various ages and risk of ovarian cancer.MethodsAmong 90,371 eligible members of the California Teachers Study cohort who completed a baseline alcohol assessment in 1995–1996, 253 women were diagnosed with epithelial ovarian cancer by the end of 2003. Multivariate Cox proportional hazards regression analysis was performed to estimate relative risks (RRs) and 95% confidence intervals (CIs).ResultsConsumption of total alcohol, beer, or liquor in the year prior to baseline, at ages 30–35 years, or at ages 18–22 years was not associated with risk of ovarian cancer. Consumption of at least one glass per day of wine, compared to no wine, in the year before baseline was associated with increased risk of developing ovarian cancer: RR = 1.57 (95% CI 1.11–2.22), Ptrend = 0.01. The association with wine intake at baseline was particularly strong among peri-/post-menopausal women who used estrogen-only hormone therapy and women of high socioeconomic status.ConclusionsAlcohol intake does not appear to affect ovarian cancer risk. Constituents of wine other than alcohol or, more likely, unmeasured determinants of wine drinking were associated with increased risk of ovarian cancer.

Reliability and Validity of an Assessment of Usual Phytoestrogen Consumption (United States)

To evaluate the reliability and validity of a food-frequency questionnaire (FFQ) and database designed to quantify phytoestrogen consumption. This study included 195 members of the California Teachers Study (CTS) cohort who, over a 10-month period, completed four 24-h dietary recalls, a pre- and post-study FFQ, and provided two 24-h urine specimens. Participants (n = 106) in a parallel study (and 18 women who dropped out of the long-term study) completed a single recall and FFQ, and provided one 24-h urine specimen. Urinary phytoestrogens were determined using liquid chromatography-mass spectrometry. Reliability and validity were evaluated using Shrout-Fleiss intraclass correlations and energy-adjusted deattenuated Pearson correlations, respectively. Correlations reflecting the reproducibility of the FFQ phytoestrogen assessment ranged from 0.67 to 0.81. Validity correlations (FFQ compared to dietary recalls) ranged from 0.67 to 0.79 for the major phytoestrogenic compounds (i.e., daidzein, genistein, and secoisolariciresinol) and 0.43 to 0.54 for the less common compounds. Compared to urinary levels, validity correlations ranged from 0.41 to 0.55 for the isoflavones and 0.16 to 0.21 for total lignans. Our isoflavone assessment is reproducible, valid, and an excellent tool for evaluating the relationship with disease risk in non-Asian populations. Further research is needed before these tools can accurately be used to assess lignan consumption.

Nonsteroidal Anti-Inflammatory Drug Use and Breast Cancer Risk by Stage and Hormone Receptor Status

Epidemiologic studies of the association between nonsteroidal anti-inflammatory drugs (NSAIDs), such as aspirin and ibuprofen, and breast cancer risk have yielded inconsistent results. We investigated the association of NSAID use with risk of breast cancer in the California Teachers Study cohort, with special attention to risk of specific breast cancer subtypes and to type of NSAID used. We analyzed data on 114 460 women in the California Teachers Study cohort who were aged 22 to 85 years and free of breast cancer at baseline in 1995 to 1996. Information on frequency and duration of NSAID use was collected through a self-administered questionnaire. A total of 2391 women were diagnosed with breast cancer during the follow-up period from 1995 to 2001. We used Cox proportional hazards regression to estimate relative risks (RR) and 95% confidence intervals (CI) of breast cancer subtypes with NSAID use. Neither regular use (more than once a week) of any NSAID (aspirin and ibuprofen combined) nor regular use of aspirin was associated with breast cancer risk (RR = 1.09, 95% CI = 0.97 to 1.21 for daily versus no regular use of NSAIDs and RR = 0.98, 95% CI = 0.86 to 1.13 for daily versus no regular use of aspirin). However, long-term (> or = 5 years) daily aspirin users had a non-statistically significant decreased risk of estrogen receptor and progesterone receptor (ER/PR)-positive breast cancer (RR = 0.80, 95% CI = 0.62 to 1.03). In contrast, we observed a statistically significantly increased risk of ER/PR-negative breast cancer with long-term daily use of aspirin (RR = 1.81, 95% CI = 1.12 to 2.92). In this population, 11 fewer ER/PR-positive breast cancer cases and seven excess ER/PR-negative breast cancer cases may be due to daily long-term aspirin use among 2391 breast cancer cases observed over 6 years if the association were proven to be causal. Long-term daily use of ibuprofen was also associated with an increased risk of breast cancer (RR = 1.51, 95% CI = 1.17 to 1.95), particularly of nonlocalized tumors (RR = 1.92, 95% CI = 1.24 to 2.97). If causality were subsequently proven, 16 of the observed 2391 breast cancer cases and 8 of the 713 non-localized breast cancer cases would be attributable to long-term daily use of ibuprofen. Long-term daily use of NSAIDs was not associated with breast cancer risk overall. Ibuprofen use was associated with an increased risk of breast cancer, and long-term daily aspirin use was associated with an increased risk of ER/PR-negative breast cancer. However, it is not clear if the observed association is causal.

Residential mobility in the California Teachers Study: implications for geographic differences in disease rates

Background: Especially for cancers with long latency periods, such as breast cancer, the issue of residential mobility hinders ecologic analyses seeking to examine the role of environmental contaminants in chronic disease etiology. This study describes and evaluates characteristics associated with residential mobility in a sub-sample of the California Teachers Study (CTS) cohort. Methods: In 2000, lifetime residential histories were collected for a sub-sample of 328 women enrolled in the CTS; women's degree of residential mobility and associated factors were analyzed. Results: While most women moved many times during their lives (average=8.9), the average number of years at their residence when they enrolled in the study was reasonably long (15.1 years). Age strongly predicted duration at current residence but was not related to the number of lifetime residences. After adjusting for age, California-born women and women living in high socioeconomic status (SES) neighborhoods were significantly more residentially stable. Agreement between self-reported urbanization of recent residences and that based on census data of the geocoded residences was very good (80% concordant). Among women currently living in urban areas, an average of 43.3 years, or 77%, of their lifetimes were spent in urban residences; among women currently living in a rural area, an average of 37.3 years, or 67% of their lifetimes were spent in rural residences. Conclusions: This suggests that analyses of incidence rates based on current residence, while not capturing a woman's full exposure history, may reasonably reflect some aspect of longer term chronic exposures, especially those related to urbanization, at least in professional women.

Correlates of active and passive smoking in the California Teachers Study cohort.

These analyses were designed to describe characteristics associated with active and passive smoking in a large cohort of women in order to identify possible confounders of the relationship between smoking exposures and breast cancer risk. Analyses were based on 1995 data collected from the California Teachers Study (CTS) and were restricted to those with complete and usable tobacco data (n = 128,174). Age-adjusted and race-adjusted odds ratios (OR) were generated by unconditional logistic regression. Compared with never smokers, both current and former smokers experienced menarche at an earlier age. Current and former smokers also were more likely than their never smoking counterparts to be nulliparous. Among parous women, current, but not former smokers were less likely than never smokers to have had their first child at an older age. Similarly, among never smokers, those exposed to household passive smoking experienced menarche at an earlier age, were more likely to be nulliparous, and among parous women, were less likely to have had their first child at an older age than never smokers not exposed to passive smoking. Greater alcohol consumption was strongly associated with both active and passive smoking exposures. Compared with never smokers, current smokers were less likely to take antioxidant supplements, whereas former smokers were more likely to take antioxidant supplements. Among never smokers, antioxidant use did not differ depending on passive smoking exposure. A number of other dietary correlates of active and passive smoking were identified. We identified a number of reproductive and dietary correlates to smoking exposures that underscore the need to adjust for such factors in an analysis of smoking and breast cancer and potentially other disease entities. Furthermore, these findings may suggest potential mechanisms underlying an association between breast cancer and smoking.

Prevalence and patterns of environmental tobacco smoke exposures among California teachers.

This study describes the prevalence and patterns of environmental tobacco smoke (ETS) exposure in a large, well-defined cohort of professional, female school employees in California. This is a cross-sectional study based on survey responses from members of the California Teachers Study (CTS) cohort. The analyses focused on lifetime nonsmokers (N = 61,899) in the CTS cohort who responded to detailed questions on lifetime ETS exposures in the home, workplace, and other social settings. Demographic characteristics, smoking status, and ETS exposure were based on self-reported data from two mailed surveys. Prevalence estimates within the cohort were compared with those from the California Behavioral Risk Factor Survey and the California Adult Tobacco Survey. ETS exposures were highest for never smokers born in the 1930s (78% in the home, 66% in the workplace, and 48% in other social settings) and steadily declined among participants born in later years. ETS exposure from spousal smoking peaked during the 1950s (37%). In the 1980s, the workplace (28%) replaced the household (19%) as the primary exposure setting. Consideration of these patterns in the prevalence of ETS exposures is important in the interpretation and design of tobacco-related health studies.

Residential proximity to agricultural pesticide use and incidence of breast cancer in the California Teachers Study cohort

We examined the association between residential proximity to agricultural pesticide use and breast cancer incidence among members of the California Teachers Study cohort, a large study of professional school employees with extensive information on breast cancer risk factors, followed for cancer incidence since 1995. We identified 1552 invasive breast cancer cases, diagnosed between 1996 and 1999, among 114,835 cohort members. We used California Pesticide Use Reporting data to select pesticides for analysis based on use volume, carcinogenic potential, and exposure potential; a Geographic Information System was used to estimate pesticide applications within a half-mile radius of subjects’ residences. We applied Cox proportional hazard models to estimate hazard rate ratios (HR) for selected pesticides, adjusting for age, race, and socioeconomic status. We saw no association between residential proximity to recent agricultural pesticide use and invasive breast cancer incidence. HR estimates for the highest compared to the lowest exposure categories for groups of agents were as follows: probable or likely carcinogens (1.07, 95% confidence interval (CI): 0.86–1.32), possible or suggestive carcinogens (1.06, 95% CI: 0.87–1.29), mammary carcinogens (1.15, 95% CI: 0.90–1.48), and endocrine disruptors (1.03, 95% CI: 0.86–1.25). HR estimates for other groups and individual pesticides did not differ from unity, nor was there a trend for any groupings of or individual pesticides examined. Stratifying by menopausal status or family history of breast cancer did not substantially affect our results. Our analyses suggest that breast cancer incidence is not elevated in areas of recent, high agricultural pesticide use in California.

Patterns of Alcohol Consumption and Breast Cancer Risk in the California Teachers Study Cohort

Abstract Alcohol consumption of approximately two drinks or more per day has been associated with elevated breast cancer risk in the California Teachers Study cohort as well as in many other populations. The objective of this analysis is to examine effects of age at drinking and drinking patterns and to identify effect modifiers. Of the 103,460 at-risk cohort members, age &amp;lt;85, who resided in California and completed the baseline alcohol assessment, 1,742 were diagnosed with invasive breast cancer after joining the cohort and before January 2001. Incident breast cancers were identified through the California Cancer Registry and follow-up for death and confirmation of continued California residence used various sources. Multivariate Cox proportional hazards regression models were used to estimate relative risks (RRs). Elevated breast cancer risk was most evident for recent drinking [RR = 1.28, 95% confidence interval (CI): 1.06–1.54 for ≥20 g/day versus nondrinkers], with no clear pattern for consumption during earlier periods of life. This elevation in risk was 32% among postmenopausal women (95% CI: 1.06–1.63) and 21% among pre/perimenopausal women (95% CI: 0.76–1.92). Highest risks associated with heavy alcohol consumption were observed among postmenopausal women with a history of biopsy-diagnosed benign breast disease (RR = 1.97, 95% CI: 1.39–2.79 compared to nondrinkers without benign breast disease) or who had used combination hormone replacement therapy (HRT) (RR = 2.24, 95% CI: 1.59–3.14 compared to nondrinkers who never used HRT). Recent alcohol consumption equivalent to two or more drinks per day increases the risk of invasive breast cancer, with the greatest RRs observed among heavy drinkers who are also postmenopausal and have a history of benign breast disease or who use HRT.

Active smoking, household passive smoking, and breast cancer: evidence from the California Teachers Study.

There is great interest in whether exposure to tobacco smoke, a substance containing human carcinogens, may contribute to a woman's risk of developing breast cancer. To date, literature addressing this question has been mixed, and the question has seldom been examined in large prospective study designs. In a 1995 baseline survey, 116 544 members of the California Teachers Study (CTS) cohort, with no previous breast cancer diagnosis and living in the state at initial contact, reported their smoking status. From entry into the cohort through 2000, 2005 study participants were newly diagnosed with invasive breast cancer. We estimated hazard ratios (HRs) for breast cancer associated with several active smoking and household passive smoking variables using Cox proportional hazards models. Irrespective of whether we included passive smokers in the reference category, the incidence of breast cancer among current smokers was higher than that among never smokers (HR = 1.32, 95% confidence interval [CI] = 1.10 to 1.57 relative to all never smokers; HR = 1.25, 95% CI = 1.02 to 1.53 relative to only those never smokers who were unexposed to household passive smoking). Among active smokers, breast cancer risks were statistically significantly increased, compared with all never smokers, among women who started smoking at a younger age, who began smoking at least 5 years before their first full-term pregnancy, or who had longer duration or greater intensity of smoking. Current smoking was associated with increased breast cancer risk relative to all nonsmokers in women without a family history of breast cancer but not among women with such a family history. Breast cancer risks among never smokers reporting household passive smoking exposure were not greater than those among never smokers reporting no such exposure. Our study provides evidence that active smoking may play a role in breast cancer etiology and suggests that further research into the connection is warranted, especially with respect to genetic susceptibilities.

Validation of self-reported cancers in the California Teachers Study.

Self-reported cancer data from the California Teachers Study were validated by using California Cancer Registry data. The California Teachers Study cohort consists of 133,479 active and retired California teachers. In 1995-1996, data from a mailed questionnaire were linked to the California Cancer Registry data. Sensitivity and specificity of 11 types of cancer were calculated. Multivariate analyses were conducted to evaluate correlates of false-positive and false-negative reporting. Sensitivities showed great variation by cancer site. The highest sensitivities were observed for breast (96.4%) and thyroid (92.9%) cancers, whereas the lowest sensitivities were those for cervical (44.3%), endometrial (69.1%), and other skin (53.6%) cancers. The sensitivities for in situ cancers (at the time of diagnosis) were considerably lower than those for invasive cancers in about half of the cancer types surveyed. The specificities for individual cancer sites ranged from 90% to 99%; the highest were those for lung cancer, leukemia, and Hodgkin's disease (all 99.9%). The lowest specificity was for other skin cancer (90.2%). In situ stage at diagnosis and older age were significantly associated with false-positive reporting. Age and non-White race were associated with false-negative reporting. These findings suggest that the feasibility of using self-reported data without verification in epidemiologic studies of cancer varies by site.

#39 Ethnic differences in dietary fat consumption among women in the california teachers study (Cts) Cohort

Abstract BACKgrOUND: As evidenced by recent trends, although there has been a decrease in the consumption of foods known by the public to have a high fat content, shifts in eating patterns may actually have lead to increased fat consumption. Greater understanding of the sources of “invisible” fats, fats found in mixed dishes and fats used in food preparation is needed. This study characterizes the types and sources of dietary fat consumption, by ethnicity and age, in a recently established cohort of California women. METHODS: Self-reported, ethnic-specific dietary data collected using an early version of the Block-95 FFQ were analyzed for 18,050 women; 3,526 Americans (AA), 5,405 Latinas (L), 4,119 Asian Americans (AsA) and a random sample of 5,000 white (W) women in the CTS cohort. Mean differences in intake of specific foods were compared; odds ratios (OR) and 95 percent confidence intervals were estimated using unconditional logistic regression adjusting for age. RESULTS: AsA and AA women consumed more calories from fat per day than did W women (OR = 1.52, 95% CI: 1.34, 1.73 and OR = 1.27, 95% CI: 1.11, 1.44, for the highest vs. the lowest quintile, respectively). However, the kind of fat consumed differed substantially. AAs consumed more saturated fat and AsAs consumed more unsaturated fat. Fat consumption among Ls was more like that of Ws but differences were seen between these two groups as well. Nonwhite women used fats in cooking more often than W women. Differences also were observed in the types of fat used in cooking. Oils, salad dressing, salty snacks, and dishes containing meat (as opposed to specific meat entrees) contributed the most to total daily fat consumption. CONCLUSION: There is considerable ethnic variation in the amount and source of dietary fat.

Correlates of vitamin supplement use in the United States: data from the California Teachers Study cohort.

To describe factors associated with vitamin supplement use in a large cohort of adult women. California teachers and administrators (n = 133,479) completed a questionnaire on lifestyle factors and medical history. Specific supplement users regularly used at least one specific vitamin supplement in the past year; multivitamin users regularly used a multivitamin; and multivitamin and specific supplement users took a multivitamin and one or more specific supplements. Associations between supplement use and other variables were quantified using means, cross-tabulations, and age-adjusted prevalence odds ratios. Multivitamin and specific supplement users tended to be older and Caucasian. Compared to non-users, they were also leaner (odds ratio [OR] for BMI > or = 30 kg/m2 = 0.6 for specific supplement users with or without multivitamins, and OR = 0.7 for multivitamin only users), and were less likely to be current smokers (OR for current smoking = 0.8 for multivitamin plus specific supplement users, OR = 0.9 for specific supplement only users, and OR = 0.7 for multivitamin only users). Specific supplement users (with or without multivitamins) were more likely to use cancer screening tests, eat fruits and vegetables, and exercise than were multivitamin only users or non-users. A variety of demographic, dietary, and health-related factors were associated with different categories of supplement use.

Recent diet and breast cancer risk: the California Teachers Study (USA).

The impact, if any, on breast cancer risk of modifying adult dietary intake is an area of much interest. We take the opportunity to address the relationship between recent adult diet and breast cancer risk during the first two years of follow-up of the large California Teachers Study cohort. Of the 111.526 at-risk cohort members who resided in California and completed a baseline dietary assessment, 711 were diagnosed with invasive breast cancer after joining the cohort and before January 1998. Average daily nutrient intake was computed based on a food-frequency questionnaire assessing usual dietary intake and portion size during the year prior to joining the cohort. Incident breast cancers were identified through the California Cancer Registry and follow-up for death and confirmation of continued California residence utilized a variety of data sources. Cox proportional hazards models were used to calculate relative hazards. The following components of recent dietary intake were not associated with breast cancer risk: energy, fat, fiber, antioxidant vitamins, and phytoestrogens. Only recent average alcohol consumption of 20 or more grams per day (approximately two or more glasses of wine) was associated with increased risk (RR= 1.5, 95% CI: 1.2-2.0 compared to non-drinkers; P(trend) = 0.01 across quintiles). With the exception of alcohol consumption, this study provides no evidence that recent macro- or micronutrient composition of adult diet is likely to have a direct effect on breast cancer risk. Some reduction of alcohol consumption among those consuming more than one drink per day may be beneficial.