Prostate cancer: trends in mortality and stage-specific incidence rates by racial/ethnic group in Los Angeles County,California (United States)

Between 1976 and 1988 in the United States, the secular trends in age-adjusted incidence rates of prostate cancer were significantly different by racial/ethnic group (P<0.001), and increased significantly only among non-Hispanic Whites at a rate of 2.7 percent (95 percent confidence interval [CI]=2.3–3.1%) annually. While incidence rates of regional disease increased significantly (7.7 percent to 11.3 percent annually) among all racial/ethnic groups during this period, localized disease increased significantly only among non-Hispanic Whites, by 1.8 percent (CI=1.4–2.3%) annually. Prostate cancer mortality in Los Angeles County (California) remained constant among Hispanics, non-Hispanic Whites, and Asians, but increased 1.6 percent (CI=0–3.2%) annually among Blacks. While the increase in localized disease rates of non-Hispanic Whites may be due to increased detection of asymptomatic disease, this apparently has not occurred among other racial/ethnic groups in Los Angeles County. The secular increase in regional disease rates among all racial/ethnic groups without a concurrent increase in mortality (except Blacks), suggests increased accuracy of staging rather than a true increase in incidence may account for these trends. Adjusted for socioeconomic status, year and age at diagnosis, Black and Hispanic men were at significantly higher risk of being diagnosed with non-localized disease (odds ratio = 1.39 and 1.24, respectively) than were non-Hispanic Whites.Drs Ross and Bernstein are also with the Cancer Surveillance ProgramThis work was supported in part by grant CA17054 from the US National Institutes of Health, and grant SIG#20 from the American Cancer Society. Cancer incidence data were collected under Subcontract 050H-8709 with the California Public Health Foundation. The subcontract is supported by the California Department of Health Services as part of its statewide cancer reporting program, mandated by Health and Safety Code Section 210 and 2113.     

Socioeconomic status and breast cancer incidence in California for different race/ethnic groups

Objective: The majority of research on breast cancer risk and socioeconomic status (SES) has been conducted for blacks and whites. This study evaluates the relationship between SES and breast cancer incidence in California for four race/ethnic groups. Methods: Principal component analysis was used to create an SES index using 1990 Census data. Untracted cases were randomly allocated to census block groups within their county of residence. A total of 97,227 female breast cancer cases diagnosed in California between 1988 and 1992 were evaluated. Incidence rates and rate ratios (RRs) were estimated and a ² test for trend across SES levels was performed. Results: SES was positively related to breast cancer incidence, and this effect was stronger for Hispanics and Asian/others than for whites and blacks. Adjusting by SES did not eliminate the differences in breast cancer rates among race/ethnic groups. RR differences between the race/ethnic groups were greatest in the lowest SES category and attenuated with increasing SES. An increasing trend over SES was statistically significant for all race/ethnic groups. Including randomly allocated cases affected RR estimates for white women only. Conclusions: Our results are consistent with similar findings for the Los Angeles area but differ from previous results for the San Francisco Bay area.     

Proportional melanoma incidence and occupation among White males in Los Angeles County (California,United States)

A case-control analysis of cancer registry data was used to examine the hypothesis that occupational exposure to sunlight influences the risk of melanoma. Occupation at diagnosis was available for 3,527 cutaneous melanomas and 53,129 other cancers identified by the Los Angeles County (California, United States) Cancer Surveillance Program among non-Spanish-surnamed White males aged 20 to 65 years between 1972 and 1990. Occupational exposure to sunlight was assessed by blinded expert coding of job titles as indoor, outdoor, and mixed indoor/outdoor. Relative to indoor occupations, proportionate odds ratios (OR) adjusted for age, level of education, and birthplace were 1.16 (95 percent confidence interval [CI]=1.07–1.27) for indoor/outdoor occupations and 1.15 (CI=0.94–1.40) for outdoor occupations. However, increasing levels of the education or training required for the occupation was associated more strongly with increased melanoma occurrence (ORs adjusted for age, occupational sun exposure, and birthplace, were 1.0, 1.63, 2.09, 2.23, and 2.99 for low-skill occupation, high school, college, postgraduate, and doctoral levels, respectively). Analysis of melanoma occurrence by job titles confirmed a clear variation by the required education or training level but not by the category of occupational sunlight exposure. The findings suggest that lifestyle factors associated with higher levels of education may be more important determinants of melanoma risk than characteristics of the work environment.where Drs London and Mack continue their affiliation. This activity has been supported in part by the California Department of Health Services as part of its statewide cancer reporting program, mandated by Health and Safety Code Section 210 and 211.3. The ideas and opinions expressed herein are those of the authors, and no endorsement of the State of California, Department of Health Services or the California Public Health Foundation is intended or should be inferred. Contract number N01-CN-25403 of the Division of Cancer Prevention and Control, National Cancer Institute, National Institutes of Health, Department of Health and Human Services provided further support for this research.     

Sexual, reproductive, and other risk factors for adenocarcinoma of the cervix: results from a population-based case-control study (California, United States)

The incidence of adenocarcinoma of the cervix increased steadily in young women in the United States between the early 1970s and the mid-1980s. Despite this increase, little is known about the etiology of this cancer, although a role for risk factors for both squamous cell carcinoma of the cervix and endometrial adenocarcinoma has been suggested. Incident cases of adenocarcinoma of the cervix diagnosed in women born after 1935 (ages 42 to 56 at diagnosis) were identified from the Los Angeles (California) County Cancer Surveillance Program (LACCSP). Data from personal interviews with 195 cases and 386 controls (matched on age, race, and neighborhood) were analyzed. Compared with women in the highest categories of education and income, women in the lowest categories had a 2.5 and 3.1-fold elevated risk of adenocarcinoma of the cervix. Number of sexual partners, especially before age 20, was strongly predictive of risk (odds ratio = 5.6, 95 percent confidence interval = 1.4–22.0 for 10 or more compared with no partners before age 20). Smoking was not associated significantly with risk. Weight gain and long-term use of oral contraceptives increased risk, while long-term diaphragm use was protective. This study suggests that both sexual and hormonal factors are important etiologic factors for adenocarcinoma of the cervix.Drs Ursin, Pike, Preston-Martin, and Peters are with the Department of Preventive Medicine, University of Southern California School of Medicine, Los Angeles, CA, USA. Dr D'Ablaing, now deceased, was with the Department of Pathology at the University of Southern California School of Medicine. Address correspondence to Dr Ursin, Department of Preventive Medicine, University of Southern California Norris Comprehensive Cancer Center, 1441 Eastlake Ave., MS#44, P.O. Box 33800, Los Angeles, CA 90033-0800, USA. This study was supported by grants P01 CA1754 and CA 44401-05 from the US National Cancer Institute, and by the California Department of Health Services, through the California Public Health Foundation, as part of its statewide cancer reporting program, mandated by Health and Safety Code Sections 210 and 211.3. The ideas and opinions expressed herein are those of the authors, and no endorsement by the State of California Department of Health Services or the California Public Health Foundation is intended or should be inferred.     

Physical activity in usual occupation and risk of breast cancer (United States)

We have used data from a large population-based case-control study inthe United States to evaluate the effect of occupational physical activity onbreast cancer risk. Women diagnosed with breast cancer identified from fourstate cancer registries, and controls randomly selected from lists oflicensed drivers or Medicare beneficiaries, were interviewed by telephone forinformation on usual occupation and other factors. We classified usualoccupation into one of four categories of physical activity. After excludingsubjects for whom a strength rating could not be assigned, we had a finalsample size of 4,863 cases and 6,783 controls. Using conditional logisticregression models, we calculated adjusted odds ratios (OR) and 95 percentconfidence intervals (CI) for occupations having light, medium, and heavyactivity compared with sedentary ones. Women with heavy-activity occupationshad a lower risk of breast cancer than women with sedentary jobs (OR = 0.82,CI = 0.63-1.08), as di d women with jobs with medium activity (OR = 0.86, CI= 0.77-0.97) or light activity (OR = 0.92, CI = 0.84-1.01). There was asignificant decreasing trend in the ORs from sedentary to heavy work (P =0.007). Although limited by exposure misclassification, these data areconsistent with the hypothesis that physical activity reduces the risk ofbreast cancer.     

Leisure-time physical activity in relation to breast cancer among young women (Washington, United States)

It has been hypothesized that women who participate in vigorous physical activity may have lower risk of breast cancer due to lower lifetime exposure to ovarian hormones. A population-based case-control study was conducted to investigate the association between leisure-time physical activity and risk of breast cancer among women aged 21 to 45 years. Cases were 747 women diagnosed with invasive breast cancer between 1983 and 1990 in three counties of western Washington state (United States), and were identified through the Seattle-Puget Sound Surveillance, Epidemiology, and End Results (SEER) registry. Controls were 961 women selected from the same area by random-digit telephone dialing. Physical activity was assessed through personal interview, with questions on frequency and duration of each type of recreational activity during the two-year period immediately prior to reference date (date of diagnosis for cases and a comparable assigned date for controls) and between ages 12 and 21. For the two-year time period before diagnosis, there was no association with frequency of activity (age-adjusted odds ratio [OR]=0.93, 95 percent confidence interval [CI]=0.71-1.22 for four or more episodes per week cf none), total hours spent in physical activity (age-adjusted OR=0.92, CI=0.71-1.22 for four or more hours per week cf none) or MET (metabolic equivalent energy expenditure unit) (age-adjusted OR=0.95, CI=0.73-1.23 for 18 or more METs per week cf none), nor any trend in risk with increasing activity levels. Similarly, there was no association between leisure activity during adolescence and breast cancer risk. These results were not confounded further by body mass index (wt/ht2), age at menarche, age at first full-term pregnancy, parity, family history of breast cancer, or other measured health behaviors. Our findings do not support a protective effect of leisure-time physical activity either in the adolescent years or in adulthood on breast cancer in young women.     

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.     

Age at menarche, time to regular cycling, and breast cancer (North Carolina, United States)

Objectives: Later menarche, and a longer time until onset of regular cycling, are considered markers of lower lifetime exposure to circulating ovarian hormones. While later age at menarche is associated with reduced breast cancer risk, evidence for the relationship between time until onset of regular cycles and breast cancer is inconsistent. We evaluated both associations with breast cancer risk.Methods: We used data from the Carolina Breast Cancer Study, a population-based case-control study of breast cancer among White and Black women aged 20 to 74 years, residing in central and eastern North Carolina (United States). Cases were diagnosed between May 1993 and June 1996. Unconditional logistic regression models were limited to women with complete data for the risk factors considered (n = 830 cases, 758 controls).Results: We observed an inverse relationship between age at menarche and breast cancer risk, but found little support for the hypothesis that a longer time until onset of regular menstrual cycling was associated with reduced risk of breast cancer (odds ratios=1.0 [95 percent confidence interval (CI) = 0.7-1.5], and 1.2 [CI = 0.8-1.6], respectively, for 1-4 years and < 1 year until onset of regular cycling, relative to 5+ years). There was little relationship between age at menarche and time until regular cycling. We found strong evidence that delays in onset of regular cycling were associated with increased frequency of irregular cycles throughout young adulthood.Conclusions: Given the inconsistent findings regarding the links between menstrual cycle characteristics and breast cancer, and recent recommendations to delay menarche and alter the patterns of cycles of young women in order to reduce breast cancer risk, this topic calls for further, innovative study.     

Dietary and other lifestyle factors of women with brain gliomas in Los Angeles County (California, USA)

A population-based interview study in Los Angeles County (California, USA) of 94 women with intracranial gliomas and 94 individually matched neighborhood controls investigated the relationship to various sources of exposure to N-nitroso compounds and their precursors and to vitamins which inhibit the endogenous formation of these compounds. The study offers some support for the hypothesis that dietary sources of nitroso exposure relate to risk. Risk increased with increasing consumption of cured meats, most notably of bacon (odds ratio [OR] for the third tertile of intake=6.6, 95 percent confidence interval [CI]=1.9-22.5, P trend < 0.001). Risk was reduced with increasing intake of vegetables such as bell peppers (OR for third tertile=0.2, CI=0.1-0.7, P trend < 0.01). In addition, use of vitamin supplements appeared protective, and there was some suggestion that eating cured meats in combination with foods which inhibit endogenous nitrosation mitigates risk. Other potential sources of nitroso exposure such as smoking, cosmetics, and drinking water did not relate to risk. Despite the limitations of data on usual adult diet, it appears that dietary sources of nitroso compounds may be important in the development of gliomas.     

Recent oral contraceptive use and risk of breast cancer (United States)

We examined the association between recent oral contraceptive (OC) use and the risk of breast cancer in data from a large population-based case-control study in the United States. Cases (n=6,751) were women less than 75 years old who had breast cancer identified from statewide tumor registries in Wisconsin, Massachusetts, Maine, and New Hampshire. Controls (n=9,311) were selected randomly from lists of licensed drivers (if aged under 65 years) and from lists of Medicare beneficiaries (if aged 65 through 74 years). Information on OC use, reproductive experiences, and family and medical history was obtained by telephone interview. After adjustment for parity, age at first delivery, and other risk factors, women who had ever used OCs were at similar risk of breast cancer as never-users (relative risk [RR]=1.1, 95 percent confidence interval [CI]=10–1.2). Total duration of usealso was not related to risk. There was a suggestion that more recent use was associated with an increased risk of breast cancer; use less than two years ago was associated with an RR of 1.3 (CI=0.9–1.9). However, only among women aged 35 to 45 years at diagnosis was the increase in risk among recent users statistically significantly elevated (RR=2.0, CI=1.1–3.9). Use prior to the first pregnancy or among nulliparous women was not associated with increased risk. Among recent users of OCs, the risk associated with use was greatest among non-obese women, e.g., among women with body mass index (kg/m²) less than 20.4, RR=1.7, CI=1.1–2.8. While these results suggest that, in general, breast cancer risk is not increased substantially among women who have used OCs, they also are consistent with a slight increased risk among subgroups of recent users.Authors are with the University of Wisconsin Comprehensive Cancer Center, Madison, WI, USA (Dr Newcomb, Ms Trentham Dietz); NIEHS Epidemiology Branch, Research Triangle Park, NC (Dr Longnecker); Fred Hutchinson Cancer Research Center, Seattle, WA (Dr Surer); Department of Obstetrics and Gynecology, Pritzker School of Medicine, The University of Chicago, Chicago, IL (Dr Mittendorf); Department of Community and Family Medicine, Dartmouth Medical School, Hanover, NH (Dr Baron); Boston University, School of Public Health, Boston, MA (Dr Clapp); Department of Epidemiology and Department of Nutrition, Harvard School of Public Health, and Channing Laboratory, Harvard Medical School and Department of Medicine, Brigham and Women's Hospital, Boston, MA (Dr Willett). Address correspondence to: Dr Polly A. Newcomb, University of Wisconsin-Madison Comprehensive Cancer Center, 1300 University Ave., #4780, Madison, WI 53706, USA. Supported by Public Health Service (National Cancer Institute) grants R01 CA 47147 and R01 CA 47305.     

Dietary relationships with early onset (under age 45) breast cancer in a case-control study in the United States: influence of chemotherapy treatment

Methodologic investigations have addressed selection and recall biasin case-control studies of diet and breast cancer, whereas the effect ofdisease progression and medical treatment on estimates of dietary intake hasbeen largely overlooked. In a multicenter, population-based case-controlstudy of breast cancer in the United States, 1,588 newly diagnosed cases and1,451 controls completed a self-administered food-frequency questionnaire.Initial evaluation suggested increased risk related to high intakes ofcalories, carbohydrates, fat, and protein. All nutrient associations werediminished after adjustment for calories. Evaluation by stage of diseaserevealed no relation of calories to risk among women with in situ disease,but elevated risks among women with localized (odds ratio [OR] = 1.33, 95percent confidence interval [CI] = 1.0-1.7 highest cf lowest quartile) orregional and distant disease (OR = 1.79, CI = 1.3-2.4). Further evaluationshowed that the increased risk a ssociated with calories was restricted tocases who reported having been treated with chemotherapy (OR = 1.66, CI =1.3-2.1). A gradient of increasing risk with time interval from diagnosis tointerview suggested the chemotherapy regimen itself and not necessarilycharacteristics of tumors requiring this treatment was responsible for theobserved increased risk. These results indicate that epidemiologic studies ofdiet and breast cancer, particularly among young women, should evaluatepossible bias related to post-diagnosis influences.     

Risk factors for extrahepatic bile duct cancers: Los Angeles County,California (USA)

Extrahepatic bile duct (EBD) cancers are rare and their risk factors are poorly understood. Except for a history of gallbladder diseases, evidence for other potential risk factors, such as excess body weight and use of tobacco and alcohol, is scant. A case-control study was conducted to examine risk factors for EBD cancers, including ampulla of Vater tumors, among Los Angeles County (California, USA) residents. Included were 105 histologically confirmed cases diagnosed between 1 March 1985 and 31 October 1989, aged 30 to 84 years, and 255 population-based controls frequency-matched to cases by gender and age in five-year groups. Cases and controls were interviewed about their demographic background and potential risk factors, including tobacco, alcohol, and beverage consumption, diet, medical history, and reproductive factors among women. For deceased cases, their next-of-kin were interviewed. Risk of cancers of both subsites of extrahepatic duct and ampulla of Vater increased with smoking of cigars/pipes or cigarettes. For both men and women, risks increased twofold or more among those who smoked cigarettes for 50 or more pack-years. While a history of gallbladder diseases substantially increased the risk of cancers of both subsites, excess body mass index was associated only with cancer of extrahepatic duct subsite (odds ratio [OR]=4.0, 95 percent confidence interval [CI]=1.1–14.2 among men and OR=2.7; CI=0.8–9.4 among women in the highest quartile relative to those in the lowest quartile). Alcohol drinkers had lower risks compared with nondrinkers, but no consistent trend was observed with amount consumed. No consistent patterns of risks were found for coffee, tea, diet, occupation, or reproductive factors. These results suggest that lifestyle-related factors, such as use of tobacco and excess body weight, play a role in EBD cancer risk.     

A population-based study of contralateral breast cancer following a first primary breast cancer (Washington, United States)

To evaluate predictors of contralateral breast cancer risk, we examined data from a nested case-control study of second primary cancers among a cohort of women in western Washington (United States) diagnosed with breast cancer during 1978 through 1990 and identified through a population-based cancer registry. Cases included all women in the cohort who subsequently developed contralateral breast cancer at least six months after the initial diagnosis, but prior to 1992 (n=234). Controls were sampled randomly from the cohort, matched to cases on age, stage, and year of initial breast cancer diagnosis. Information on potential risk factors for second primary cancer was obtained through medical record abstractions and physician questionnaires. Women who were postmenopausal due to a bilateral oophorectomy (i.e., a surgical menopause) at initial breast cancer diagnosis had a reduction in contralateral breast cancer risk compared with premenopausal women (matched odds ratio [mOR]=0.25, 95 percent confidence interval [CI]=0.09–0.68), whereas no reduction in risk was noted among postmenopausal women who had had a natural menopause (mOR=0.90, CI=0.39–2.09). Among postmenopausal women, there was a suggestion of a lower risk associated with relatively high parity (2+). A family history of breast cancer was associated with an increased risk (mOR=1.96, CI=1.22–5.15) and varied little by menopausal status. Having an initial tumor with a lobular component (c.f. a ductal histology) was not related strongly to risk (mOR=1.47, CI=0.79–2.74). The results of the present and earlier studies argue that we have limited ability to predict the occurrence of a contralateral breast tumor. Better predictors will be required before diagnostic and preventive interventions can be targeted to subgroups of patients with unilateral breast cancer.Authors are with the Department of Epidemiology, University of Washington, Seattle, WA, USA (Drs Cook, White, Schwartz, Daling, Weiss); with the Fred Hutchinson Cancer Research Center, Seattle, WA (Drs Cook, White, Schwartz, McKnight, Daling, Weiss); and the Department of Biostatistics, University of Washington, Seattle, WA (Dr McKnight). Address correspondence to Dr Cook, MP-381, Fred Hutchinson Cancer Research Center, 1124 Columbia Street, Seattle, WA 98104, USA. This research was supported in part by grants from the US National Cancer Institute (R35 CA 39779), the Agency for Health Care Policy and Research (1 RO3 HS08004-01), and by the Cancer Surveillance System of the Fred Hutchinson Cancer Research Center, which is funded by Contract No. N01-CN-05230 from the Surveillance, Epidemiology and End Results (SEER) program of the National Cancer Institute with additional support from the Fred Hutchinson Cancer Research Center.     

Hormone replacement therapy, reproductive history, and colon cancer: a multicenter, case-control study in the United States

Hormonal factors have been inconsistently associated with coloncancer risk in women. The associations between reproductive events, menstrualfactors, exogenous hormones, and colon cancer were evaluated in a largecase-control study (894 female cases and 1,120 female age-matchedpopulation-based controls) in the United States, stratifying by age atdiagnosis, tumor site, family history and other potential risk factors.Overall, higher parity was associated with a marginally decreased risk ofcolon cancer (five or more births compared with nulliparous: odds ratio [OR]= 0.75, 95 percent confidence interval [CI] = 0.53-1.06) after adjusting forage at diagnosis, family history of colorectal cancer, vigorous lifetimephysical activity, body mass index (BMI) (wt/ht 1.5 ), total energy intake,and aspirin use. No important associations were observed for otherreproductive or menstrual events. An inverse association between recent useof hormone replacement therapy (HRT) and colon cancer was observed (OR = 0.71, CI = 0.56-0.89). Although interaction termswere not significant, this inverse association appeared to be more pronouncedfor those with an older age at diagnosis; for those without a first-degreerelative with colorectal cancer; and for those with a relatively low BMI. Thereduced risk associated with HRT use did not appear to be explained by otherbehaviors related to HRT use.     

Using central cancer-registry data to monitor progress in early detection of breast and cervical cancer (Illinois,United States)

Cases of breast and cervical cancer account for almost 40 percent of all cancers diagnosed in Illinois (United States) women. Information on screening rates, however, is not collected routinely for the populations at risk. This paper reports on surveillance indicators designed to identify target populations and evaluate programs. All cases of cancers of the breast (n=38,824, including in situ) and invasive cervix (n=2,763) with a known stage, among women aged 40 to 74, were identified through the population-based Illinois State Cancer Registry for 1986 to 1992. The proportion of breast cancer cases with in situ disease-stage and cervical cancer cases with a late invasive stage were selected as surveillance indicators. Differences by age and race were evaluated, as were age-and race-specific trends. The data suggest that Black women, aged 40 to 74 years, and White women, aged 65 to 74 years, should be targeted for breast-cancer-screening interventions. All women, aged 40 to 74, should be targeted for enhanced cervical-cancer-screening interventions. Significant trends in in situ breast cancer diagnoses were apparent in all age-race groups, however no significant decline in invasive cervical cancer was found for any age-race group. The indicators identified the age- and race-specific disparities among potential target populations for breast and cervical cancer screening.The work was supported in part by a grant from the Centers for Disease Control and Prevention, number U57/CCU508384.     

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.     

Strenuous physical activity in young adulthood and risk of breast cancer (United States)

The epidemiologic data on the relation between strenuous physical activity and breast cancer are limited and inconsistent. Because risk of breast cancer may be influenced by ovarian function which, in turn, is modulated by physical activity, the hypothesis that exercise may be associated with a reduced risk of breast cancer merits further investigation. We, therefore, conducted a large case-control study in 1988–91, and interviewed 6,888 women (17 to 74 years of age) with breast cancer in Maine, Massachusetts, New Hampshire, and Wisconsin (United States). Interviewed controls (9,539 women, 18 to 74 years of age) were selected randomly from lists of licensed drivers (for younger women) or from a roster of Medicare enrollees (for older women). We used multivariate adjusted odds ratios (OR) and 95 percent confidence intervals (CI) from logistic regression models to estimate relative risks between self-reported physical activity when 14 to 22 years of age and breast cancer. When compared with sedentary controls, women who reported any strenuous physical activity during ages 14 to 22 years had a modest reduction in the risk of breast cancer (OR=0.95, CI=0.93–0.97). However, those who exercised vigorously at least once a day had a 50 percent reduction in risk of breast cancer (OR=0.5, CI=0.4–0.7). These data support the hypothesis that women who are physically active have a reduced risk of breast cancer.This project is funded by grants (R01 CA 47147 and R01 CA 47305) from the US Public Health Service.Dr Mittendorf was also supported by National Research Service Award No. 5 T32 ES07069.     

Determinants of breast cancer detection among Wisconsin (United States) women, 1988–90

Early detection is advocated widely as the best method to reduce the high rate of breast cancer mortality in women. The purpose of this study was to describe the detection histories of women with breast cancer and to identify factors related to the method of detection. During the period 1988–90, 3,197 women with invasive breast cancer, identified through the Wisconsin (United States) tumor registry, were interviewed. The method of cancer detection (classified as self, screening mammography, or clinical breast examination [CBE]) was analyzed using polychotomous logistic regression. Fifty-five percent (1,754/3,197) of the women found their own cancers, while 35 percent (1,122/3,197) were detected by screening mammography. Compared with self-detection, the likelihood of non-localized disease was significantly lower for tumors detected by mammography (odds ratio [OR]=0.3, 95 percent confidence interval [CI]=0.2–0.4) and CBE (OR=0.6, CI=0.4–0.7). The likelihood of cancer being detected by screening mammography increased with increasing age, education, number of prior mammograms, family history, and body mass index (weight/height²) (BMI). Women in the highest BMI quintile were 2.3 times (CI=1.7–3.0) more likely than women in the lowest BMI quintile to have their cancers diagnosed by mammography. This association most likely results from breast tumors being more difficult to palpate in heavier women.This work was undertaken while Dr Reeves was an Epidemic Intelligence Officer, assigned to the Wisconsin Division of Health from the Division of Field Epidemiology, Centers for Disease Control and Prevention, Atlanta, GA, USA.     

Menopausal estrogen and estrogen-progestin replacement therapy and risk of breast cancer (United States)

This study examines the relationship between menopausal estrogen and estrogen-progestin replacement therapy and risk of breast cancer, focusing on whether associations differ according to whether the tumors arein situ or invasive. Data are from a prospective study conducted 1980–89 on 49,017 selected participants in the Breast Cancer Detection Demonstration Project, a five-year screening program conducted between 1973 and 1980 in the United States. Overall, the rate ratio for estrogen-only use compared with no-hormone use was 1.0, and that for the estrogen-progestin combination was 1.2 (95 percent confidence interval [CI]=1.0–1.6). However, the associations differed according to whether the tumors werein situ or invasive. The rate ratios ofin situ breast cancer associated with use of estrogens alone and the combination regimen were 1.4 (CI=1.0–2.0) and 2.3 (CI=1.3–3.9), respectively. Duration of estrogen-only use also was associated with risk ofin situ tumors, with users for 10 or more years at twice the risk of nonusers (P-value for trend test =0.02). Duration of use was not associated with risk of in vaisve cancer. Our results are consistent with the hypothesis that hormone replacement therapy is related to earlier-stage breast cancer; however, the possibility that the results reflect increased breast cancer surveillance among those taking hormones cannot be ruled out.