Reproductive factors and family history of breast cancer in relation to plasma estrogen and prolactin levels in postmenopausal women in the Nurses' Health Study (United States)

Parity, age at first birth, age at menarche, and a family history of breast cancer have each been associated consistently with breast cancer risk. Whether this increase in risk is mediated, at least in part, through changes in endogenous hormone levels is unclear. We conducted a cross-sectional study of the relationships between these factors and plasma hormone levels in 216 healthy postmenopausal women in the Nurses' Health Study (United States). The hormones evaluated were estradiol, percent and total free estradiol, percent and total bioavailable estradiol, estrone, estrone sulfate, and prolactin. After controlling for age, body mass index (weight/height²), and alcohol use, we observed inverse associations between estrone sulfate and parity (r=–0.15, P=0.03) and between percent bioavailable estradiol and age at first birth (r=–0.17, P=0.02). Although women with a family history of breast cancer tended to have higher estrogen levels compared with women without such history, the differences were not statistically significant. Age at menarche was not related significantly to any of the hormones. These data provide some additional evidence that the inverse relationship observed between parity and breast cancer risk may be mediated, at least in part, through decreased estrogen levels. Our data do not support a substantial influence of either family history of breast cancer or age at menarche on postmenopausal estrogen or prolactin levels.Authors are with the Channing Laboratory (Drs Hankinson, Colditz, Hunter, Manson, Willett, Stampfer, Speizer) and Divislon of Preventive Medicine (Dr Manson), Brigham and Women's Hospital and Harvard Medical School, Boston, MA (USA); Departments of Nutrition (Drs Willett, Stampfer), and Epidemiology (Drs Hankinson, Colditz, Hunter, Willett, Stampfer), Harvard School of Public Health, Boston, MA; and the Departments of Obstetrics and Gynecology and Medicine, University of Massachusetts Medical School, Worcester, MA (Dr Longcope). Address correspondence to Dr Hankinson, Channing Laboratory, 180 Longwood Ave., Boston, MA 02115, USA. This research was supported by research grants CA40356 and CA49449 from the US National Institutes of Health, Bethesda, MD. Dr Manson is a recipient of a Merk/Society for Epidemiologic Research grant award.     

Whole and refined grain intake and risk of incident postmenopausal breast cancer (United States)

Objective: To assess the relation between whole and refined grain intake and risk of incident postmenopausal breast cancer. Findings from case–control studies of whole and refined grain intake and risk of postmenopausal breast cancer have been inconclusive. Methods: The Iowa Women's Health Study is a prospective cohort study of women initially 55–69 years old that relates diet and other lifestyle factors to cancer risk. After exclusions a total of 29,119 menopausal women who answered a 1986 baseline and a 1989 follow-up questionnaire were followed for 9 years for incident breast cancer. Results: Compared to women who at baseline rarely ate whole grain foods, women who habitually ate whole grain had a healthier lifestyle, including a higher likelihood of prior screening mammography. The multivariate-adjusted risk of incident breast cancer was 20% higher in women in the highest quintile of whole grain intake, compared to women in the lowest quintile of whole grain intake (95% confidence interval 0.95–1.5; p-value for trend = 0.03). No increase in breast cancer risk was found in women who had not undergone screening mammography before 1989; the apparent increase in risk was therefore likely due to increased use of screening mammography. Refined grain intake was not associated with breast cancer risk. Conclusion: Consistent with inverse but not statistically significant associations between whole grain intake and breast cancer in case–control studies, both whole and refined grain intakes are unrelated to risk of postmenopausal breast cancer in these Iowa women.     

Alcohol consumption and postmenopausal endometrial cancer: results from the Iowa Women's Health Study

At least three case-control studies have examined the association between alcohol consumption and endometrial cancer; two studies showed inverse associations, and a third a positive association. To our knowledge, no prospective studies of this association have been reported. The association between alcohol and endometrial cancer was examined in the Iowa Women's Health Study (United States), a prospective study of postmenopausal women. Information on alcohol consumption and other variables was obtained through a mailed questionnaire in January 1986. Through December 1990, 167 incident endometrial cancer cases occurred in the at-risk cohort of 25,170 women. Multivariate-adjusted relative risks (RR) and 95 percent confidence intervals (CI) were computed using Cox proportional hazards regression controlling for age, body mass index (BMI), parity, age at menopause, and noncontraceptive estrogen use, and to determine multiplicative interactions. The RRs of endometrial cancer associated with <4.0 and 4.0 g of alcohol per day compared with abstainers were 0.7 (CI=0.5–1.1) and 1.0 (CI=0.7–1.6), respectively. No statistically significant association between endometrial cancer and consumption of either beer, wine, or liquor was observed. There was no interaction between alcohol and any other endometrial cancer risk factors, including BMI or noncontraceptive estrogen use. These data do not support an association between alcohol and endometrial cancer among postmenopausal women.This project was supported by grant RO1-CA39742 to Dr Folsom from the US National Cancer Institute; the contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Cancer Institute. Dr Gapstur was supported by NIH training grant T32-CA09607 to Dr Potter.     

Reproductive risk factors for incident bladder cancer: Iowa Women's Health Study

We studied the association between reproductive factors and bladder cancer incidence in a prospective cohort study of 37,459 Iowa women aged 55-69 years and initially free from cancer in 1986. Women reported reproductive history and were followed prospectively through 2003. After adjusting for age and smoking, there was an inverse association between age at menopause and incident bladder cancer (n = 192). Compared with menopause at age > or =48, the hazard ratio (HR) of bladder cancer was 1.32 (95% CI; 0.90-1.94) for menopause at 43-47, and 1.60 (95% CI; 1.06-2.39) for < or =42 (p-trend = 0.02). The associations were similar for ages at natural and surgical menopause. In addition, women with a history of bilateral oophorectomy had an increased risk of bladder cancer compared with those who did not undergo bilateral oophorectomy: HR = 1.58 (95% CI; 1.12, 2.22). Finally, there was an indication of a positive association between bladder cancer and shorter lifetime years of ovulation (p-trend = 0.09). There were no associations between incident bladder cancer and age at first birth, number of births, age at menarche, use of hormone replacement therapy or any other reproductive characteristics. This study provides evidence that increased risk of bladder cancer is associated with earlier age at menopause in postmenopausal women.     

Effect of family history,obesity and exercise on breast cancer risk among postmenopausal women

We examined effects of obesity and lifetime exercise patterns on postmenopausal breast cancer risk according to family history in a large population-based case control study conducted in Los Angeles County, California, because we hypothesized that both factors would affect risk through similar mechanistic pathways, and that their effects would be stronger among women with a family history. We studied 1883 postmenopausal breast cancer case subjects and 1628 postmenopausal control subjects ranging in age from 55-72 years. Cases were diagnosed with incident breast cancer in the late 1980s and 1990s. Controls were individually matched to case subjects on age, ethnic origin and neighborhood. In-person interviews determined known breast cancer risk factors including: height, weight, lifetime exercise, and family history of breast and other cancers. Breast cancer risk was raised among women who had at least 1 first-degree relative with breast cancer (odds ratio [OR] = 1.68; 95% confidence interval [CI] = 1.36-2.08). Risk increased with increasing levels of body-mass index (wt-kg/ht-m(2)) (p-trend = 0.005). Breast cancer risk was reduced among women who maintained, on average, 17.6 metabolic equivalent of energy expenditure (MET)-hr of activity/week from menarche onward (OR = 0.66; 95% CI = 0.48-0.90). Body-mass index, adjusted for lifetime exercise, was strongly associated with breast cancer risk among women with a positive family history of breast cancer (p-trend < 0.0001), but only weakly associated among women with no family history (p-trend = 0.08; homogeneity of trends p = 0.0005). In contrast, the risk reduction associated with exercise activity, adjusting for body-mass index, was limited to women without a family history of breast cancer (p-trend = 0.001; homogeneity of trends p = 0.005). Body-mass index and exercise activity, both modifiable risk factors for breast cancer, seem to have differential effects depending on a woman's family history of breast cancer, and may impact risk through different biological mechanisms.     

Interaction of family history of breast cancer and dietary antioxidants with breast cancer risk (New York,United States)

We sought to determine if specific dietary antioxidants may be particularly effective in reducing breast cancer risk for women reporting family history (FH) of breast cancer in a first-degree relative. Interviews regarding usual diet, health, and family histories were conducted with 262 premenopausal and 371 postmenopausal women with incident, primary breast cancer from western New York (United States). These women were frequencymatched by age and county of residence with community controls. Among premenopausal women, there was a significant interaction between FH and -tocopherol; -tocopherol was associated with significantly decreased risk among FH+ women (adjusted fourth-quartile odds ratio [OR]=0.01, 95 percent confidence interval [CI]=0.0–0.3). This association was much weaker for FH-women [OR=0.7, CI=0.4–1.2]. For FH-women, a significant inverse association was observed between -carotene and premenopausal breast-cancer risk (OR=0.4, CI=0.3–0.5), but not for FH+ women (OR=0.5, CI=0.1–4.0). Similar relationships, although not as strong, were noted among postmenopausal women. Although limited by small numbers, these results suggest that biologic mechanisms of tumorigenesis may differ in FH+ and FH-women, and that -tocopherol may be a potential chemopreventive agent for women with a family history of breast cancer, particularly premenopausal women.This research was conducted by the Department of Social and preventive Medicine, State University of New York at Buffalo. This publication is supported in part by grants CA11535 and 5 R25 CA1820117 from the US National Cancer Institute and PDT-434 from the American Cancer Society. Dr Freudenheim is a recipient of a Research Career Development Award from the National Cancer Institute (CA01633). This work is solely the responsibility of the authors and does not necessarily represent the views of the NCI.     

Diet and risk of colon cancer in a large prospective study of older women: an analysis stratified on family history (Iowa, United States)

Objective: The purpose was to investigate whether dietary associations with risk of colon cancer in women differ by family history of the disease.Methods: Data were analyzed from a prospective cohort study of 35,216 Iowa (United States) women aged 55 to 69 years at baseline. Through 31 December 1995, 241 colon cancers were identified through record linkage with the State Health Registry. The cohort was stratified on family history of colon cancer in first-degree relatives; nutrient intakes were divided into tertiles.Results: Analyses using Cox regression revealed that the association of most dietary components with colon cancer incidence were similar for individuals with and without a family history. However, total calcium intake was associated inversely with colon cancer among women with a negative family history (relative risk [RR]=0.50 for upper cf lower tertile, P < 0.001), but was unrelated to incidence for women with a positive family history (RR=1.1 for upper cf lower tertile, P=0.69). Similarly, total vitamin E intake was associated with lower risk among women with a negative family history (RR=0.67 for upper cf lower tertile, P=0.04), but not among women with a positive family history (RR=0.87 for upper cf lower tertile, P=0.67). High intakes of fiber, fruits, and vegetables were each weakly inversely associated with risk among family-history negative women, but not among family-history positive women.Conclusions: These data, if corroborated, suggest that dietary factors typically associated with lower risk may be less effective risk-reduction interventions against colon cancer for individuals with a family history of colon cancer.     

Meat consumption and risk of breast cancer in the UK Women's Cohort Study

We performed a survival analysis to assess the effect of meat consumption and meat type on the risk of breast cancer in the UK Women's Cohort Study. Between 1995 and 1998 a cohort of 35 372 women was recruited, aged between 35 and 69 years with a wide range of dietary intakes, assessed by a 217-item food frequency questionnaire. Hazard ratios (HRs) were estimated using Cox regression adjusted for known confounders. High consumption of total meat compared with none was associated with premenopausal breast cancer, HR=1.20 (95% CI: 0.86-1.68), and high non-processed meat intake compared with none, HR=1.20 (95% CI: 0.86-1.68). Larger effect sizes were found in postmenopausal women for all meat types, with significant associations with total, processed and red meat consumption. Processed meat showed the strongest HR=1.64 (95% CI: 1.14-2.37) for high consumption compared with none. Women, both pre- and postmenopausal, who consumed the most meat had the highest risk of breast cancer.     

Reproductive factors and colon cancer: the influences of age,tumor site,and family history on risk (Utah,United States)

The Utah (United States) Population Database was used to evaluate the associations between reproductive factors and colon cancer risk and the impact that family history, age at diagnosis, and tumor site have on these associations. From the cohort of (White) women in the database, all first-primary cases of colon cancer (n=819) and controls who had complete fertility information (n=3, 202) were examined. The majority of tumors (68.6 percent) among women diagnosed at age 64 years or less were in the distal segment of the colon, while among women 65 or older, the majority of tumors (55.7 percent) were proximal. Women diagnosed before age 65 had a lower risk of colon cancer with increasing numbers of liveborn children (odds ratio [OR]=0.6, 95 percent confidence interval [CI]=0.3–0.9 for women with five or more children compared with women with one or two children). A long interval between first and second births (first birth-interval) was associated with increased risk of tumors in the distal segment of the colon (OR=1.4, CI=1.0–2.0) and among women diagnosed before age 65 (OR=1.6, CI=1.0–2.5); a longer, average birth-interval was associated with increased risk of proximal tumors (OR=1.5, CI=1.1–2.1). A longer, first birth-interval increased the risk associated with a family history of colon cancer, as did a longer average birth-interval and an older age at first or last birth. From these data, it appears that reproductive factors have heterogeneous effects on the risk of colon cancer that vary with age at diagnosis, tumor site, and family history of disease.This study was supported by grant and contract numbers CA48998 and CN0552 from the US National Cancer Institute. Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Cancer Institute.     

Family history and risk of breast cancer in hispanic and non-hispanic women: the New Mexico Women's Health Study

Objectives: Many epidemiologic studies have demonstrated that an increased risk of breast cancer is associated with positive family history of this disease. Little information had been available on the relationship of breast cancer risk with family history in Hispanic women. To investigate the association of family history of breast cancer on the risk of breast cancer, we examined the data from the New Mexico Women's Health Study (NMWHS), a statewide case–control study. Methods: In this study 712 women (332 Hispanics and 380 non-Hispanic whites) with breast cancer and 844 controls (388 Hispanics and 456 non-Hispanic whites) were included. Conditional logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (95% CI), adjusted for sociodemographic, medical, and reproductive factors. Results: We found an increased risk in women with a history of breast cancer in one or more first-degree or second-degree relatives (OR = 1.5, 95% CI 1.2–1.9), first-degree relatives (OR = 1.3, 95% CI 1.0–1.8) and second-degree relatives (OR = 1.6, 95% CI 1.2–2.2). Hispanic women had higher risk estimates for a positive family history (OR = 1.7, 95% CI 1.1–2.5) than non-Hispanic white women (OR = 1.4, 95% CI 1.0–2.0); however, the differences were not statistically significant. In both ethnic groups a higher risk was observed in premenopausal women compared with postmenopausal women and women diagnosed with breast cancer before age 50years compared with older women. Conclusions: The results indicate that Hispanic women with a family history of breast cancer are at increased risk of breast cancer.     

Estrogen replacement therapy and risk of fatal breast cancer in a prospective cohort of postmenopausal women in the United States

This study examines the relationship between fatal breast cancer and use of estrogen replacement therapy (ERT) among women in a large prospective study in the United States. After nine years of follow-up, 1,469 breast cancer deaths were observedin a cohort of 422,373 postmenopausal women who were cancer free at study entry and who supplied information on estrogen use. Results from Cox proportional hazards modeling, adjusted for 11 other potential risk factors, showed that ever-use of ERT was associated with a significantly decreased risk of fatal breast cancer (rate ratio [RR]=0.84,95 percent confidence interval [CI]=0.75–0.94). There was a moderate trend (P=0.07) of decreasing risk with younger age at first use of ERT. This decreased risk was most pronounced in women who experienced natural menopause before the age of 40 years (RR=0.59, CI=0.40–0.87). There was no discernible trend of increasing risk with duration of use in estrogen users at baseline or former users, nor was there any trend in years since last use in former users. The relationship between ERT and breast cancer mortality differed by age at menarche and by a self-reported history of breast cysts. No increased risk of fatal breast cancer with ERT was observed with estrogen use status (baseline/former), age at first use, duration of use, or years since last use. These findings suggest that ever-use of ERT is associated with a 16 percent decreased risk of fatal breast cancer.     

Risk factors for meningioma in postmenopausal women: results from the Iowa Women's Health Study

Few risk factors for meningioma, aside from increasing age and female sex, have been identified. We investigated risk factors for meningioma in elderly women, a group with a high incidence. We evaluated associations of demographic, lifestyle, medical history, and anthropometric variables with risk of meningioma in the Iowa Women's Health Study (IWHS), a population-based, prospective cohort study. Risk factors were collected via questionnaires mailed in 1986 and 1992. Incident meningiomas were identified via linkages to Medicare. Cox regression models were used to examine the association of risk factors with meningioma incidence. The mean age at baseline of the 27,791 women in the analysis cohort was 69.3 years (range, 65.0-84.6 years). During 291,021 person-years of follow-up, 125 incident meningiomas were identified. After adjusting for age, lower levels of physical activity (relative risk [RR] , 0.68 for high versus low; P for trend = .039), greater body mass index (BMI; RR, 2.14 for ≥35 versus 19.5-24.9 kg/m(2); P for trend = .0019), greater height (RR, 2.04 for >66 versus ≤62 inches; P for trend = .013), and a history of uterine fibroids (RR, 1.72; 95% confidence interval, 1.19, 2.50) were positively associated with meningioma risk in multivariate analysis. BMI at age 18 and 30 years were not associated with risk. There were no associations with menstrual or reproductive factors or other medical history and lifestyle factors. Physical activity, BMI, height, and history of uterine fibroids were associated with meningioma risk in older women. The positive association with height suggests a role for early life influences on risk, whereas the associations with BMI and physical activity suggest a role for modifiable factors later in life.     

Type of postmenopausal hormone use and risk of breast cancer: 12-year follow-up from the Nurses' Health Study

We prospectively examined the use of hormone replacement therapy in relation to breast cancer incidence in a cohort of women 30 to 55 years of age in 1976. During 12 years of follow-up (480,665 person-years) among postmenopausal women, 1,050 incident cases of breast cancer were documented. Overall, past users of replacement estrogen were not at increased risk. After adjustment for established risk factors, type of menopause, age at menopause, and current age, the rate ratio (RR) was 0.91, 95 percent confidence interval (CI) = 0.78–1.07. the risk of breast cancer was elevated significantly among current users (RR = 1.33, CI = 1.12–1.57); after adjusting for age, we observed no evidence of increasing risk with increasing duration of use among current users (P trend = 0.41), or among past users (P trend = 0.46). Women currently using unopposed estrogen (RR = 1.42, CI = 1.19–1.70), estrogen and progesterone (RR = 1.54, CI = 0.99–2.39), or progesterone alone (RR = 2.52, CI = 0.66–9.63), were all at increased risk of breast cancer compared with never users. These data suggest that long-term past use of estrogen replacement therapy is not related to risk, that current estrogen use increases risk of breast cancer to a modest degree, and that the addition of progesterone does not remove the increased risk observed with current use of unopposed estrogen.The authors are with the Nurses' Health Study, Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, MA; and Harvard Medical School, Boston, MA, USA. Address correspondence to Dr Colditz, Channing Laboratory, 180 Longwood Ave., Boston, MA 02115-5899, USA. Supported by research grant CA40356 from the National Cancer Institute, NIH, Department of Health and Human Services. Dr Colditz is supported by an American Cancer Society Faculty Research Award FRA-398.     

Sugar,meat, and fat intake,and non-dietary risk factors for colon cancer incidence in Iowa women (United States)

To investigate the relation of dietary intakes of sucrose, meat, and fat, and anthropometric, lifestyle, hormonal, and reproductive factors to colon cancer incidence, data were analyzed from a prospective cohort study of 35,215 Iowa (United States) women, aged 55–69 years and without a history of cancer, who completed mailed dietary and other questionnaires in 1986. Through 1990, 212 incident cases of colon cancer were documented. Proportional hazards regression was used to adjust for age and other risk factors. Risk factors found to be associated significantly with colon cancer included: (i) sucrose-containing foods and beverages other than ice cream/milk; relative risks (RR) across the quintiles=1.00, 1.73, 1.56, 1.54, and 2.00 (95% confidence intervals [CI] for quintiles two and five exclude 1.0); (ii) sucrose; RR across the quintiles=1.00, 1.70, 1.81, 1.82, and 1.45 (CI for quintiles two through four exclude 1.0); (iii) height; RR=1.23 for highest to lowest quintile (P for trend-0.02); (iv) body mass index; RR=1.41 for highest to lowest quintile (P for trend=0.03); and (v) number of livebirths, RR=1.59 for having had one to two livebirths and 1.80 for having had three or more livebirths compared with having had none (P for trend=0.04). These data support hypotheses that sucrose intake or being tall or obese increases colon cancer risk; run contrary to the hypothesis that increased parity decreases risk; support previous findings of no association with demographic factors other than age, cigarette smoking, or use of oral contraceptives or estrogen replacement therapy; and raise questions regarding previous associations with meat, fat, protein, and physical activity.Cancer Causes and Control 1994, 5, 38–52.This project was supported by research grant CA 39742 from the US National Cancer Institute.     

Reproductive factors and family history of breast cancer in relation to plasma prolactin levels in premenopausal and postmenopausal women

Many reproductive factors are associated with breast cancer risk, potentially through a hormonal pathway. The peptide hormone prolactin is essential in mammary development and lactation and may be a link between risk factors and breast cancer. While higher prolactin levels are associated with increased breast cancer risk, few determinants of prolactin levels are known. We conducted a cross-sectional analysis among 1,089 premenopausal and 1,311 postmenopausal women within the Nurses' Health Study (NHS) and the NHS II to examine the associations of reproductive factors, benign breast disease and family history of breast cancer with plasma prolactin levels. Parous women had significantly lower prolactin levels than nulliparous women (parous vs. nulliparous multivariate-adjusted geometric means = 14.1 ng/mL vs. 16.6 ng/mL, p<0.001 for premenopausal and 9.1 vs. 10.1, p=0.04 for postmenopausal women), although levels did not decrease with increasing number of children for either premenopausal (p-trend = 0.23) or postmenopausal (p-trend = 0.07) parous women. Age at first birth was not associated with prolactin levels. The reduction in prolactin levels among parous premenopausal women appeared to attenuate with increasing time since first birth, but the trend was not statistically significant (p-trend = 0.12). Age at menarche, duration of lactation and benign breast disease were not associated with prolactin levels. Family history of breast cancer was associated with significantly higher prolactin levels when compared with no family history among premenopausal (15.9 ng/mL vs. 14.3 ng/mL, p=0.04) but not postmenopausal (p=0.73) women. In conclusion, the associations of parity and family history with breast cancer risk may be mediated, at least in part, by prolactin levels.     

BRCA1 susceptibility markers and postmenopausal breast cancer: the Iowa Women's Health Study.

Much research on early-onset breast cancer families has been performed and has shown that breast cancer in many of these families is linked to either BRCA1 or BRCA2. Fewer studies have examined the role of genetic predisposition in postmenopausal breast cancer. A nested case-control family study of breast cancer was conducted within the Iowa Women's Health Study, a population-based prospective study of 41,836 postmenopausal women. Probands were 251 incident cases diagnosed between 1988 and 1989. Three-generation pedigrees were developed through mailed questionnaires. From this collection of pedigrees, thirteen were identified for more detailed genetic analysis. Sibling-pair linkage analyses were performed using polymorphic markers in candidate regions in these 13 families with multiple cases of breast and other cancers. Four of the DNA markers are located on chromosome 17, and two of these (D17S579 and THRA1) flank the BRCA1 locus. Significant evidence for linkage to D17S579 was obtained in the total sample, in a model without inclusion of covariates or age at onset (P = 0.005), and in a model adjusted for five measured covariates and for variable age at onset (P = 0.008). Complete sequencing of the BRCA1 gene in these families, including all intron/exon boundaries, failed to reveal any mutations in 24 women with breast cancer from the 13 families. These data suggest that in some families identified by postmenopausal breast cancer cases, breast cancer risk may be mediated by a gene (or genes) in the BRCA1 region, but not BRCA1 itself.     

Dietary catechins and cancer incidence among postmenopausal women: the Iowa Women's Health Study (United States)

Objective: Catechins are bioactive flavonoids present in tea, fruits, and vegetables. Previous epidemiological studies regarding tea and cancer risk were inconclusive, possibly because catechins are also present in other plant foods. We investigated whether a high intake of catechins are associated with cancer incidence among postmenopausal women. Methods: A cohort of 34,651 postmenopausal cancer-free women aged 55–69 years were followed from 1986 to 1998. At baseline, data on diet, medical history, and lifestyle were collected. Incident cancers were obtained through linkage with a cancer registry. Cox proportional hazards analysis was used to estimate risk ratios. Results: After adjustment for potential confounders, catechin intake was inversely associated with rectal cancer incidence only (risk ratios from lowest to highest quartile: 1.00, 0.93, 0.73, and 0.55; p for trend 0.02). Non-significant inverse trends were found for cancer of the upper digestive tract, pancreas, and for hematopoietic cancers. Catechins derived primarily from fruits, (+)-catechin and (–)-epicatechin, tended to be inversely associated with upper digestive tract cancer, whereas catechins derived from tea were inversely associated with rectal cancer. Conclusions: Among several cancers studied, our data suggest that catechin intake may protect against rectal cancer. The distinct effects found for catechins derived from solid foods (fruits) and beverages (tea) may be due to differences in bioavailability or metabolism of the catechins, or to their interactions with other dietary components.     

A prospective study of oral contraceptive use and risk of breast cancer (Nurses' Health Study, United States)

Results of previous epidemiologic studies have provided reassurance that there is little, if any, increase in risk of breast cancer with oral contraceptive (OC) use in general. However, in several studies, an increased risk of breast cancer has been observed in two subgroups, young women who used OCs for extended durations and in women who used OCs prior to a first-term pregnancy. We evaluated these relationships using data from the ongoing Nurses' Health Study cohort (United States). We documented 3,383 cases of breast cancer from 1976 to 1992 among 1.6 million person-years of follow-up. We observed no overall relationship between duration of OC use and breast cancer risk, even among women who reported using OCs for 10 or more years (multivariate relative risk [RR]=1.11, 95 percent confidence interval [CI]=0.94-1.32). Among women less than 45 years of age, the multivariate RR for using OCs for 10 or more years was 1.07 (CI=0.70-1.65) compared with never-users. The risk associated with five or more years of OC use prior to a first full-term pregnancy compared with never-use was 0.96 (CI=0.65-1.43). Among women less than 45 years of age, we observed no evidence of an increased risk with OC use before a first full-term pregnancy (use for five or more years: RR=0.57, CI=0.24-1.31). Because of the age distribution of our cohort, we were unable to evaluate these relationships among women less than 40 years of age. Our study provides considerable evidence that long-term past OC use, either overall or prior to a first full-term pregnancy, does not result in any appreciable increase in breast cancer risk in women over 40 years of age.