A review of physical activity and breast cancer

High Injury and Concussion Rates in Female Youth Team Sport: An Opportunity for Prevention

The aim of this study was to investigate sport-related injury rates, types, locations, and mechanisms in female youth team sports.This was a secondary analysis of a cross-sectional study. An anonymous online survey was administered to high school students (ages 14-19) in Canada. The survey included questions regarding demographic information, sport participation and self-reported injuries sustained in the past year. Results were analyzed for girls who reported playing a top ten team sports for female participation. For girls participating in team sports, the overall injury rate was 55.5 injuries/100 participants/year. The rate of at least one concussion was 9.4 concussions/100 participants/year. Injury and concussion rates were highest in ringette (Injury rate=42.9 injuries/100 participants/year, Concussion rate=19.0 concussions/100 participants/year) and rugby (Injury rate=40.0, Concussion rate=15.3). The top three most serious injury locations were the knee (24.7%), ankle (21.6%) and head (16.1%). The most common injury types were joint/ligament sprain (26.71%), fracture (13.0%) and concussion (11.8%). Contact mechanisms accounted for 73.4% of all serious injuries reported in girls team sports.Team sport injury rates are high in female youth team sports. Specific consideration of sport-specific injury rates, types and mechanisms in girls' team sports will inform development and evaluation of targeted sport-specific prevention strategies.

Physical activity reduces breast cancer risk: a case-control study in Tunisia

PURPOSE

This study examined the relationship between lifetime history of physical activity and breast cancer risk.

METHODS

The case-control study was conducted on 400 women with histological confirmed breast cancer operated during the 2006-2009 period at Farhat Hached University Hospital, Sousse, Tunisia, and 400 cancer-free controls, aged 25-75 years. The physical activity was assessed using a structured questionnaire on each activity: type, duration, frequency, and intensity. Odds ratios (ORs), 95% confidence intervals (CI) and a full confounding assessment, included in this analysis, were derived using logistic regression.

RESULTS

These cases had lower lifetime averages for total physical activity for both forms of activity measurements (hours/week/year and MET-hours/week/year) and (P(trend)<0.001 and P(trend)=0.002, respectively). Significant risk reductions were found in total physical activity for both forms of activity measurements (OR=0.27, 95% CI: 0.18-0.52, OR=0.42, 95% CI: 0.26-0.73, respectively) for the highest versus the lowest level of activity (P(trend)=0.001 and 0.004, respectively). The stratification by menopausal status showed a significant 56% reduction in breast cancer risk for post-menopausal women (P(trend)=0.001, adjusted for age). The risk was further reduced to 68% (P(trend)=0.002, multivariate adjusted). Among pre-menopausal women, the total physical activity was not significantly associated with reduced risk, ORs were 0.88 (95% CI: 0.40-1.99, age adjusted) and 0.43 (95% CI: 0.12-1.38, multivariate adjusted).

CONCLUSION

These data are in concordance with the majority of previous reports which involved physical inactivity as an important risk factor for breast cancer.

Validation of the historical adulthood physical activity questionnaire (HAPAQ) against objective measurements of physical activity

BACKGROUND

Lifetime physical activity energy expenditure (PAEE) is an important determinant of risk for many chronic diseases but remains challenging to measure. Previously reported historical physical activity (PA) questionnaires appear to be reliable, but their validity is less well established.

METHODS

We sought to design and validate an historical adulthood PA questionnaire (HAPAQ) against objective PA measurements from the same individuals. We recruited from a population-based cohort in Cambridgeshire, UK, (Medical Research Council Ely Study) in whom PA measurements, using individually calibrated heart rate monitoring, had been obtained in the past, once between 1994 and 1996 and once between 2000 and 2002. 100 individuals from this cohort attended for interview. Historical PA within the domains of home, work, transport, sport and exercise was recalled using the questionnaire by asking closed questions repeated for several discrete time periods from the age of 20 years old to their current age. The average PAEE from the 2 periods of objective measurements was compared to the self-reported data from the corresponding time periods in the questionnaire.

RESULTS

Significant correlations were observed between HAPAQ-derived and objectively measured total PAEE for both time periods (Spearman r = 0.44; P < 0.001). Similarly, self-reported time spent in vigorous PA was significantly correlated with objective measurements of vigorous PA (Spearman r = 0.40; P < 0.001).

CONCLUSIONS

HAPAQ demonstrates convergent validity for total PAEE and vigorous PA. This instrument will be useful for ranking individuals according to their past PA in studies of chronic disease aetiology, where activity may be an important underlying factor contributing to disease pathogenesis.

The adolescent female athlete: current concepts and conundrums

The adolescent female athlete has become a common part of the sports environment at all levels from childhood play to professional adult sports. This article considers various issues common to this athlete to help clinicians care for their patients. Basic sports physiology is reviewed and then specific conditions are considered, including iron deficiency anemia, stress urinary incontinence, breast issues (ie, pain, asymmetry, galactorrhea, injury), the female athlete triad (ie, menstrual dysfunction, abnormal eating patterns, and osteopenia or osteoporosis), and injuries. Clinical conundrums are considered including the difficulty in caring for a dedicated athlete whose intense love of her sport may lead to menstrual and bone loss complications. The knowledgeable clinician in the twenty-first century can be of considerable help to the female athlete who is at and beyond puberty.

Physical activity and survival after breast cancer diagnosis: meta-analysis of published studies

Published data have shown that physical activity (PA) has a positive role on the primary prevention of breast cancer risk. However, the role of PA on breast cancer outcome has been controversial with inconsistent data. The lack of a meta-analysis that addresses that issue prompted the current report. A comprehensive literature search identified eight studies, of which two studies were excluded. The remaining six studies (12,108 patients with breast cancer) were included in this meta-analysis. Pre-diagnosis PA reduced all causes mortality by 18% but had no effect on breast cancer deaths. Post-diagnosis PA reduced breast cancer deaths by 34% (HR=0.66, 95% CI, 0.57-0.77, P<0.00001), all causes mortality by 41% (HR=0.59, 95% CI, 0.53-0.65, P<0.00001), and disease recurrence by 24% (HR=0.76, 95% CI, 0.66-0.87, P=0.00001). Breast cancer mortality was reduced by pre-diagnosis PA in women with body mass index (BMI)<25 kg/m2, while post-diagnosis PA reduced that risk among those with BMI≥25 kg/m2. On the other hand, post-diagnosis PA reduced all causes mortality regardless of the BMI. The analysis showed that post-diagnosis PA reduced breast cancer deaths (HR=0.50, 95% CI, 0.34-0.74, P=0.0005), and all causes mortality (HR=0.36, 95% CI, 0.12-1.03, P=0.06) among patients with estrogen receptor (ER)-positive tumor, while women with ER-negative disease showed no gain. The current meta-analysis provides evidence for an inverse relationship between PA and mortality in patients with breast cancer and supports the notion that appropriate PA should be embraced by breast cancer survivors.

Physical activity and breast cancer risk among women in the southwestern United States

Physical activity may influence breast cancer risk through multiple mechanisms and at different periods in life. In this study we evaluate breast cancer risk associated with total and vigorous physical activity at ages 15, 30, and 50 years and the referent year prior to diagnosis/selection. Participants were non-Hispanic white (NHW) (1527 cases and 1601 control subjects) and Hispanic/American Indian (HAI) (798 cases and 924 controls) women. Both total and vigorous activity reduced risk of breast cancer in a dose-response manner. Among premenopausal women, only high total metabolic equivalent of the task (MET) hours of activity during the referent year was associated with reduced breast cancer risk in NHW women (odds ratio [OR] 0.62; 95% confidence interval [CI] 0.43, 0.91). Among postmenopausal women, physical activity had the greatest influence among women not recently exposed to hormones. Among these women, high total lifetime activity reduced risk of breast cancer for both NHW (OR 0.60; 95% CI 0.36, 1.02; p trend 0.01) and HAI women (OR 0.52; 95% CI 0.23, 1.16; p trend 0.07). Additionally, high total MET hours of activity at age 30 years (OR 0.56; 95% CI 0.37, 0.85) and at age 15 years (OR 0.57; 95% CI 0.38, 0.88) reduced breast cancer risk among postmenopausal NHW women not recently exposed to hormones. Among HAI women, more recent activity performed during the referent year and at age 50 appeared to have the greatest influence on breast cancer risk. Among postmenopausal NHW women. there was a significant interaction between physical activity and hormone replacement therapy (p value, 0.01), while among postmenopausal HAI women, physical activity interacted with body mass index (p value, 0.04). These data suggest that physical activity is important in reducing risk of breast cancer in both NHW and HAI women.

Physical Activity and Breast Cancer

BACKGROUND

Many epidemiologic studies have found an association between physical activity and breast cancer risk, although this has not been a consistent finding.

METHODS

Studies were identified through a systematic review of literature available on PubMed through February 2006. We included all cohort and case-control studies that assessed total or leisure time activities in relation to occurrence or mortality of breast cancer. The fully adjusted risk estimates and 95% confidence intervals for the highest versus lowest level of activity were documented for each study as well as evidence for a dose-response relationship. Methodologic quality was also assessed. Due to statistical and methodologic heterogeneity among studies, we did not carry out statistical pooling. To draw conclusions, we performed a best-evidence synthesis taking study quality into account.

RESULTS

Nineteen cohort studies and 29 case-control studies were evaluated. There was strong evidence for an inverse association between physical activity and postmenopausal breast cancer with risk reductions ranging from 20% to 80%. For premenopausal breast cancer, however, the evidence was much weaker. For pre- and postmenopausal breast cancer combined, physical activity was associated with a modest (15-20%) decreased risk. Evidence for a dose-response relationship was observed in approximately half of the higher-quality studies that reported a decreased risk. A trend analysis indicated a 6% (95% confidence interval = 3% to 8%) decrease in breast cancer risk for each additional hour of physical activity per week assuming that the level of activity would be sustained.

CONCLUSIONS

There is evidence for an inverse association between physical activity and breast cancer risk. The evidence is stronger for postmenopausal breast cancer than for premenopausal breast cancer.

Fatness at birth predicts adult susceptibility to ovarian suppression: an empirical test of the Predictive Adaptive Response hypothesis

Poor fetal environments are thought to produce adaptive changes in human developmental trajectories according to the Predictive Adaptive Response hypothesis. Although many studies have demonstrated correlations between indicators of fetal environment and negative adult health outcomes, the adaptive significance of these outcomes is unclear. Our study explicitly tests the adaptive nature of fetal programming in humans. We show that differences in nutritional status at birth are associated with adaptive differences in the sensitivity of adult ovarian function to energetic stress. Women who were born as relatively fat babies do not exhibit ovarian suppression in response to moderate levels of physical activity at adulthood, in contrast to women who were born as skinnier babies. The levels of estradiol in women born in the highest tertile of ponderal index (an indicator of neonatal nutritional status) were 37% and 46% higher, respectively, than levels of estradiol in women born in the low and middle ponderal index tertiles. These findings suggest that fetal programming of reproductive function results in developmentally plastic, but essentially adaptive, shifts in set points of ovarian response to energetic stress, such that women who were gestated under conditions of energetic constraint show greater sensitivity to energetic stress in adulthood. Our results have practical implications in terms of behavioral strategies for reducing the risk of breast cancer. We suggest that the amount of activity necessary to reduce levels of estrogen, which may in turn reduce cancer risk, can depend on a woman's nutritional status at birth.

Physical activity patterns and obesity in Hispanic and non-Hispanic white women

PURPOSE

Cultural differences in diet and lifestyle patterns probably contribute to cancer rates among ethnic groups in the United States. In this paper, we describe physical activity patterns of Hispanic and non-Hispanic white women living in the southwestern United States and the effects of these patterns on obesity.

METHODS

We use data from population-based controls (N = 2039) participating in the 4-Corner's Breast Cancer Study to evaluate associations between physical activity and language acculturation and the associated effects on obesity.

RESULTS

The majority of both Hispanic and non-Hispanic white women did not perform 30 min of activity > or = 5 d x wk(-1), although a greater percentage of Hispanic women meet the goal if they reported higher levels of language acculturation. However, the type and intensity of activities performed by Hispanic and non-Hispanic women differed; Hispanic women reported more housework, dependent care giving, dancing, and work activity. Differences in activity patterns existed by level of language acculturation among Hispanic women. Hispanic women who had higher levels of language acculturation reported continued activity throughout their lives. Prevalence of obesity was greater among Hispanic than non-Hispanic white women for all levels of language acculturation. Women with intermediate levels of language acculturation had the greatest relative risk of obesity compared with non-Hispanic white women (odds ratio (OR) = 2.79, 95% confidence interval (CI) = 1.85-4.02); Hispanic women with higher levels of language acculturation also were at increased relative risk of obesity (OR = 1.78, 95% CI = 1.28-2.47).

CONCLUSIONS

Interventions to increase physical activity among Hispanic women are needed to address the problems of physical inactivity and obesity in that population. Facilitating culturally relevant activities might be reasonable approaches to increasing physical activity.

Energy balance and breast cancer risk: a prospective cohort study

While there is evidence that breast cancer risk is positively associated with body mass index (in postmenopausal women) and energy intake and inversely associated with physical activity, few studies have examined breast cancer risk in association with energy balance, the balance between energy intake and expenditure. Therefore, in the cohort study reported here, we studied the independent and combined associations of vigorous physical activity, energy consumption, and body mass index (BMI), with breast cancer risk. The investigation was conducted in 49,613 Canadian women who were participants in the National Breast Screening Study (NBSS) and who completed self-administered lifestyle and food frequency questionnaires between 1980 and 1985. Linkages to national mortality and cancer databases yielded data on deaths and cancer incidence, with follow-up ending between 1998 and 2000. During a mean 16.4 years of follow-up, we observed 2545 incident breast cancer cases. Due to exclusions for various reasons, the analyses were based on 40,318 subjects amongst whom there were 1673 incident cases of breast cancer. Participation in vigorous physical activity and body mass index were not independently associated with breast cancer risk in the total cohort. A statistically significant positive trend was observed, however, between energy intake and breast cancer risk (P (trend )= 0.01). Although there was some variation in risk associated with vigorous physical activity, and BMI when the analyses were stratified by menopausal status, these interactions were not statistically significant. The interaction between menopausal status and energy intake, however, was of borderline statistical significance (P (interaction )= 0.06), with a statistically significant increased risk of breast cancer associated with highest versus lowest quartile of energy intake among premenopausal women (Hazard Ratio [HR] = 1.45, 95% confidence interval [CI] = 1.13- 1.85, P (trend) = 0.001). There was evidence of an increased risk of breast cancer associated with a relatively high body mass index among postmenopausal women in the highest quartile level of energy intake (Hazard Ratio [HR] = 1.72, 95% confidence interval [CI] = 1.01- 2.93, P (trend) = 0.05). In addition, there was evidence of an increased risk of breast cancer among premenopausal, physically inactive, overweight/obese women who consumed > or =1972 kcal/day compared to physically active normal weight women who consumed <1972 kcal/day (HR = 1.60, 95% CI = 1.08-2.37). Our data suggest that obese premenopausal women with relatively high energy intake may be at increased risk of breast cancer. In addition, energy imbalance, represented by a relatively high energy intake, lack of participation in vigorous physical activity, and a relatively high body mass index, may be associated with increased breast cancer risk, particularly among premenopausal women.

A combined breast health/weight loss intervention for Black women

BACKGROUND

Overall incidence of breast cancer is slightly lower, but mortality rates are higher, for Black women compared to White women. Higher body mass index (BMI), sedentary lifestyles, and lower compliance with recommended breast health behaviors may contribute to higher risk and mortality.

METHODS

A randomized pilot intervention trial was conducted to assess feasibility and efficacy of a combined breast health/weight loss intervention for 64 overweight or obese Black women, ages 35-65. The primary objectives were to determine whether a 20-week (twice weekly) intervention could decrease weight and dietary fat intake and increase physical activity and breast self-exam (BSE) proficiency.

RESULTS

The project was implemented in two cohorts and retention was high for both (96% and 89%, respectively). Both cohorts showed increased proficiency in BSE in the intervention versus the control group (2.4 vs. -0.4, P<0.05; 3.3 vs. -0.2, P<0.001, respectively), but only cohort 2 showed decreased percent body weight (4.0% decrease vs. 0.9% increase, P<0.01), increased physical activity frequency (2.4 vs. 0.1 times/week, P<0.05), and a trend for decreased dietary fat (-2.6% kcal vs. 0.0% kcal, P=0.07) in the intervention compared to the control group.

CONCLUSION

Few studies have documented weight loss among Black women, and no combined breast health/weight loss intervention has been conducted. This study documents the feasibility of recruiting, randomizing, and retaining women in a combined intervention and demonstrated weight loss and associated lifestyle changes.

Physical activity in adolescence and young adulthood and breast cancer risk: a quantitative review

Physical activity habits are potentially modifiable and could therefore be targeted in a primary prevention strategy against breast cancer, provided there is causality and a sufficiently strong relationship. Our objective of this quantitative review was to provide a summary estimate of the association of moderate/vigorous recreational physical activity during adolescence/young adulthood with breast cancer risk, and to determine whether a dose-response relationship exists. Data sources included studies in humans relating physical activity to breast cancer risk, published between January 1966 and October 2002, identified on Medline, the Web of Science, from reference lists and related reviews. The main characteristics of each study, the point estimates of relative risk (RR) and confidence intervals (CI) were extracted from 19 case-control and four cohort studies. Comparing the highest to the lowest category of physical activity, the summary RR from the random effects model was 0.81 (95% CI 0.73-0.89). This almost 20% risk reduction proved to be fairly consistent, despite variation in populations and methods. Each one-hour increase of recreational physical activity/week during adolescence was associated with a 3% (95% CI 0-6%) risk reduction. Physical activity in 12-24-year-old females significantly reduces risk of breast cancer. Heterogeneity may be explained by different methods to measure activity.

Energetic factors and seasonal changes in ovarian function in women from rural Poland

Female mammals can optimize their fitness by temporal suppression of reproductive function in response to unfavorable environmental conditions. Since reproduction is energetically demanding for a human female, ovarian function is expected to be sensitive to factors influencing energy availability and metabolism. Dieting and exercise in women from industrial countries, and low-calorie diet and workload in women from developing countries, are often associated with ovarian suppression. This study shows that in Polish rural women seasonal changes in workload correlate with seasonal changes in indices of ovarian function (progesterone measured in saliva samples collected daily for six menstrual cycles for each subject). Mean levels of energy expenditure of the most work demanding weeks of the summer exceeded mean levels of energy expenditure during winter by 37%. Energy intake in this population was sufficient throughout the year. During the summer, when physical work was most intense, low values of progesterone levels were observed (178.2 pmol/L in July and 182.2 pmol/L in August), indicating ovarian suppression. Mean progesterone levels rose to 234.6 pmol/L in October when levels of energy expenditure were lower due to cessation of harvest-related activities. As indicated by several causal models tested through path analysis, energy expenditure was the only variable responsible for suppressed progesterone levels during the summer. Variables describing the nutritional status and energy balance did not correlate significantly with progesterone levels; neither body weight nor body fat or seasonal changes of these variables seem to influence ovarian function in this population. Thus work-related energy expenditure does not need to lead to negative energy balance in order to cause suppression of reproductive function in women.

Estimating physical activity using the CSA accelerometer and a physical activity log

PURPOSE

To compare two methods for measuring time spent in physical activity of differing absolute intensities.

METHODS

Over a 7-d period, 59 women wore Computer Science and Applications, Inc. (CSA) accelerometers and recorded their activity in physical activity logs (PAL) at 15-min intervals. Three published cut points were used to classify CSA data into resting/light, moderate, and vigorous intensity categories. Data were analyzed using descriptive statistics, Spearman rank-order correlations, and Bland-Altman plots.

RESULTS

The CSA estimates of total (moderate plus vigorous) physical activity using the three cut points ranged from a mean (+/- SD) of 38.1 (+/-26.8) min.d-1 to 312.6 (+/- 101.1) min.d-1. Using the PAL, women self-reported a mean (+/- SD) of 75.1 (+/- 51.7) min.d-1 of total activity. There was fair to modest rank-order agreement between each of the three CSA measures and the PAL measure of total activity, with correlations ranging from r = 0.15 to 0.24. Correlations between CSA and PAL estimates of total activity were higher in women with body mass index values (BMI) below 25 kg.m-2 (r = 0.23-0.38) compared with women with BMI > or = 25 kg.m-2 (r = 0.06-0.08) but did not differ according to age. Correlations between the three CSA cut points ranged from r = 0.45 to 0.86.

CONCLUSIONS

Three published cut points designed to classify CSA output by intensity level produced different estimates of physical activity participation. Correlations between CSA and PAL measures of activity intensity were fair overall but higher among leaner women.

Exposures in childhood, adolescence and early adulthood and breast cancer risk: a systematic review of the literature

A growing body of work indicates that exposures over the life course have important roles to play in the aetiology of breast cancer. This review synthesises the literature that has been published in the area of early life events and female breast cancer risk. The review finds some evidence, primarily from cohort studies on the relationship between birthweight and breast cancer, to suggest that in utero events are related to breast cancer risk in adulthood. Strong evidence to support a positive association between height and breast cancer exists. Postulated mechanisms for this relationship include the role of early diet in subsequent disease risk, and the influence of endogenous growth factors mediating the relationship. There is some evidence to suggest that leg length is the component of height which is generating the observed associations between height and breast cancer. There is no consistent pattern of association between relative weight in childhood or adolescence and risk of breast cancer. The evidence to suggest an association between physical activity in early life and breast cancer risk is convincing from case-control studies, but is not fully substantiated by the results of three cohort studies. There are inconsistent results regarding the association between smoking at a young age and breast cancer risk. There is little evidence for an association between passive smoking in early life and breast cancer risk. No clear association between early drinking and breast cancer risk exists. These results are discussed in relation to possible underlying mechanisms and health promotion strategies which could reduce breast cancer risk.

Exercise, cachexia, and cancer therapy: a molecular rationale

Evidence from recent publications indicates that repeated exercise may enhance the quality of life of cancer patients. The lack of reported negative effects and the consistency of the observed benefits lead one to conclude that physical exercise may provide a low-risk therapy that can improve patients' capacity to perform activities of daily living and improve their quality of life. Repeated physical activity may attenuate the adverse effects of cancer therapy, prevent or reverse cachexia, and reduce risk for a second cancer through suppression of inflammatory responses or enhancement of insulin sensitivity, rates of protein synthesis, and anti-oxidant and phase II enzyme activities. These results most likely come about through the ability of physical exercise to attenuate a chronic inflammatory signaling process and to transiently activate the mitogen-activated protein kinase, c-Jun NH2-terminal kinase, c-Jun NH2-terminal kinase-mitogen-activated protein kinase, and nuclear factor-kappa B pathways and through its ability to enhance insulin sensitivity. Expanded molecular-based research into these areas may provide new insights into the biological mechanisms associated with cancer rehabilitation and endogenous risk.

The female athlete. Before and beyond puberty

As the twentieth century progressed, the female athlete became an accepted participant of sports at all levels. This article reviews various aspects of female sports participation. After an historical perspective, selected comments are provided on psychologic and physiologic aspects. Concepts of adolescent gynecology are reviewed, including breast and menstrual problems and pregnancy. Other areas reviewed include iron deficiency anemia, stress urinary incontinence, and sports injuries in female athletes.

Validity and reproducibility of a physical activity questionnaire in women

PURPOSE

To determine the validity and reproducibility of a self-administered physical activity questionnaire that assesses the frequency, intensity, and duration of recreational, household, and occupational activity in women.

METHODS

The questionnaire was administered by mail twice to 131 participants 1 yr apart. During this interval, participants completed four 1-wk activity logs corresponding to different seasons throughout the year.

RESULTS

The intraclass correlation coefficients used to measure reproducibility were 0.82 for total activity, 0.79 for moderate activity, 0.86 for vigorous activity, 0.80 for recreational activity, and 0.73 for household activity. The distribution of activity scores was similar between the questionnaires and the average of the four logs, indicating the participants' ability to incorporate seasonal variation into their recall on a questionnaire. The correlations between the questionnaire-based activity scores and log-based activity scores, indicating validity, were 0.26 for total activity, 0.15 for moderate activity, and 0.52 for vigorous activity. Women younger than age 50 tended to have higher validity scores than women aged 50 yr and older (r = 0.31 vs r = 0.19, respectively, for total activity).

CONCLUSION

These data indicate that this physical activity questionnaire is reproducible and provides a useful measure of current activity, particularly vigorous activity, over a 1-yr period.

Epidemiology of breast cancer in older women: implications for future healthcare

Breast cancer in elderly women is already a significant public health problem. Elderly women have a 6-fold higher breast cancer incidence rate and 8-fold higher mortality rate compared with non-elderly women. Because of demographic trends, the number of elderly women diagnosed with breast cancer is likely to increase substantially in the coming decades. Specifically, if incidence rates remain constant, we project a 72% increase in the number of elderly women in the US diagnosed with breast cancer by 2025, an increase from approximately 89,500 in 1998 to almost 154,000 in 2025. If this projection holds true, the sheer magnitude of the increase in patients has profound implications for the delivery of medical care. Considerable planning is needed to ensure that the infrastructure is in place to effectively treat these patients. The burgeoning number of elderly patients with breast cancer accentuates the need for more definitive evidence concerning preventing and treating breast cancer in the elderly. Treatment patterns for elderly patients with breast cancer have been shown to differ from those for non-elderly patients, but the evidence base for differentiating treatment plans by age is deficient. For example, information is needed to tease apart the relative importance of age per se compared with important age-related factors, such as comorbidity. Patient care will benefit from an interdisciplinary team approach that includes oncologists, geriatricians, surgeons, radiation oncologists, nurses and social workers. The continued increase in life expectancy necessitates well-crafted strategies for the primary and secondary prevention of breast cancer. Carefully addressing the priorities for breast cancer prevention and control in the elderly during the first portion of the century may reap substantial dividends by the end of the century.

Epidemiology of endocrine-related risk factors for breast cancer

Ovarian and other hormones are major determinants of breast cancer risk. Particularly important is the accumulative exposure of the breast to circulating levels of the ovarian hormones estradiol and progesterone. A number of breast cancer risk factors can be understood in light of how they affect women's hormone profiles. Age is a marker for the onset and cessation of ovarian activity. Racial differences in hormone profiles correlate with breast cancer incidence patterns. Age at menarche not only serves as the chronological indicator of the onset of ovarian activity, but as a predictor of ovulatory frequency during adolescence and hormone levels in young adults, and has a long-lasting influence on risk. Age at menopause, another established breast cancer risk factor, marks the cessation of ovarian activity. Pregnancy history and lactation experience also are hormonal markers of breast cancer risk. Postmenopausal obesity, which is associated with higher levels of estrogen following cessation of ovarian activity, increases breast cancer risk, whereas physical activity, which can limit menstrual function, reduces risk. A relatively recent area of investigation is prenatal exposures like preeclampsia and low birth weight; both may be associated with lower in utero exposure to estrogen and also may predict lower breast cancer risk as an adult. Improved understanding of these exposures and their potential interactions with breast cancer susceptibility genes may, in the future, improve our prospects for breast cancer prevention.

Physical activity, anthropometric factors and risk of pancreatic cancer: results from the Canadian enhanced cancer surveillance system

To explore the hypothesis that insulin resistance may be an etiologic factor in pancreatic cancer, we assessed the pancreatic cancer risk associated with anthropometric factors and physical activity, both of which are important determinants of insulin sensitivity in humans. Three hundred and twelve patients with histologically confirmed pancreatic cancer were compared to 2,919 controls in a population-based, case-control study in 7 of the 10 Canadian provinces. Participants were asked to report their exposure status for the period 2 years before interview. Men in the highest quartile of body mass index (BMI, > or =28.3 kg/m(2)) were at increased risk of pancreatic cancer [adjusted odds ratio (OR) = 1.90, 95% confidence interval (CI) 1.08-3.35]. In addition, men who reported a decrease in weight of at least 2.9% from their lifetime maximum were at reduced risk compared to those reporting a < or =2.9% loss (> or =10.2% loss, OR = 0.51, 95% CI 0.30-0.86). BMI 2 years before interview was not associated with pancreatic cancer risk among women, though those reporting a > or =12.5% decrease in weight from their lifetime maximum had substantially lower risk compared to those in the baseline quartile (OR = 0.53, 95% CI 0.29-0.99). After adjustment for age, province of residence, dietary intake and anthropometric factors, men in the highest quartile of the composite moderate and strenuous physical activity index were at reduced risk of pancreatic cancer (OR = 0.53, 95% CI 0.31-0.90). Physical activity did not appear to be associated with pancreatic cancer among women, though a tendency for reduced risk with increasing levels of strenuous activity was suggested (p for trend = 0.06). Our findings support the hypothesis that insulin resistance is an etiologic factor in the development of pancreatic neoplasms among men and possibly women.

Relationships of physical activity with dietary behaviors among adults

BACKGROUND

Physical activity and diet are important influences on health, but few data are available about the relationship between these two factors. The purpose of this study was to examine relationships between physical activity and dietary quality and to identify determinants of the combination of sedentary behavior and suboptimal diet.

METHODS

The design of this study was cross-sectional. The setting was a large managed-care organization and the participants were 1,322 racially diverse men and women ages 25-91 years. We categorized subjects' physical activity into vigorous, moderate, and sedentary based on answers to two validated interviewer-administered questions about intensity and duration of specified activities. Dietary assessment was by means of a validated short food frequency questionnaire. We defined suboptimal diet as consuming unhealthful quantities of at least two of the following five food groups: fruits, vegetables, whole grain foods, whole-fat dairy foods, and red and processed meats.

RESULTS

Seven hundred fifty-four (57%) subjects were sedentary and 617 (47%) consumed a suboptimal diet. Using multiple linear regression, we found that sedentary individuals consumed smaller amounts of foods and nutrients considered to be healthful, such as fruits and vegetables, fiber, calcium, folate, and vitamins A, C, and E, than more active participants. For nutrients considered to be harmful, such as saturated fat, trans fat, and dietary cholesterol, the association with physical activity was inverse. In multiple logistic regression analyses, the strongest sociodemographic correlates of the joint presence of inactivity and poor diet were less education [odds ratio for 1-year decrease 1.14 (95% confidence interval 1.06, 1.22)], nonwhite race [1.48 (1.05, 2.07)], and nonmarried status [1.49 (1.06, 2.10)].

CONCLUSIONS

Physical activity and diet quality are correlated behaviors. Suboptimal diet and sedentary behavior tend to cluster in individuals who are less educated, not married, and of nonwhite race. Programs that target diet and activity together, informed by their joint determinants, may attain enhanced outcomes.

Energetic factors, ovarian steroids and the risk of breast cancer

In industrial countries, women often have excess metabolic energy due to high food consumption and low physical activity. High lifetime energy availability results in high lifetime levels of ovarian steroid hormones. Oestrogens and progesterone are hypothesized to play a crucial role in the development and prognosis of breast cancer. Epidemiological studies document the importance of physical activity and caloric limitations in reducing breast cancer risk. The risk of breast cancer is much higher in industrial countries than in developing countries, where women are characterized by lower energy intake and higher energy expenditure. It is likely, that the beneficial effects of physical activity and of negative energy balance are mediated by the reduced levels of ovarian steroids. While both weight loss and physical activity may have similar efficacy in suppressing ovarian function and, therefore, in reducing the risk of breast cancer, we suggest that it may be more advantageous for premenstrual women to achieve lifetime reduction in steroid levels by increasing their physical activity, rather than by weight loss due to caloric restriction alone.

Exercise and the immune system: regulation, integration, and adaptation

Stress-induced immunological reactions to exercise have stimulated much research into stress immunology and neuroimmunology. It is suggested that exercise can be employed as a model of temporary immunosuppression that occurs after severe physical stress. The exercise-stress model can be easily manipulated experimentally and allows for the study of interactions between the nervous, the endocrine, and the immune systems. This review focuses on mechanisms underlying exercise-induced immune changes such as neuroendocrinological factors including catecholamines, growth hormone, cortisol, beta-endorphin, and sex steroids. The contribution of a metabolic link between skeletal muscles and the lymphoid system is also reviewed. The mechanisms of exercise-associated muscle damage and the initiation of the inflammatory cytokine cascade are discussed. Given that exercise modulates the immune system in healthy individuals, considerations of the clinical ramifications of exercise in the prevention of diseases for which the immune system has a role is of importance. Accordingly, drawing on the experimental, clinical, and epidemiological literature, we address the interactions between exercise and infectious diseases as well as exercise and neoplasia within the context of both aging and nutrition.

Diminishing educational differences in breast cancer mortality among Finnish women: a register-based 25-year follow-up

OBJECTIVES

This study examined trends in breast cancer mortality by education, age, and birth cohort.

METHODS

Census records of Finnish women 35 years and older were linked with death records for 1971 through 1995.

RESULTS

Excess breast cancer mortality of more-educated women has declined rapidly, mainly because of increasing mortality among less-educated women and stable or decreasing mortality among more-educated 35- to 64-year-old women. During the 1990s, mortality among more-educated 50- to 64-year-old women declined particularly fast.

CONCLUSIONS

The causes of declining differences by education in breast cancer mortality are difficult to verify, but they may be due in part to narrowing differences in reproductive behavior among the younger birth cohorts and to a period effect possibly associated with the introduction of breast cancer screening in the late 1980s.

Alternative therapies used by women with breast cancer in four ethnic populations

BACKGROUND

Interest in alternative therapies is growing rapidly in the United States. We studied the types and prevalence of conventional and alternative therapies used by women in four ethnic groups (Latino, white, black, and Chinese) diagnosed with breast cancer from 1990 through 1992 in San Francisco, CA, and explored factors influencing the choices of their therapies.

METHODS

Subjects (n = 379) completed a 30-minute telephone interview in their preferred language. Logistic regression models assessed factors associated with the use of alternative therapies after a diagnosis of breast cancer.

RESULTS

About one half of the women used at least one type of alternative therapy, and about one third used two types; most therapies were used for a duration of less than 6 months. Both the alternative therapies used and factors influencing the choice of therapy varied by ethnicity. Blacks most often used spiritual healing (36%), Chinese most often used herbal remedies (22%), and Latino women most often used dietary therapies (30%) and spiritual healing (26%). Among whites, 35% used dietary methods and 21% used physical methods, such as massage and acupuncture. In general, women who had a higher educational level or income, were of younger age, had private insurance, and exercised or attended support groups were more likely to use alternative therapies. About half of the women using alternative therapies reported discussing this use with their physicians. More than 90% of the subjects found the therapies helpful and would recommend them to their friends.

CONCLUSIONS

Given the high prevalence of alternative therapies used in San Francisco by the four ethnic groups and the relatively poor communication between patients and doctors, physicians who treat patients with breast cancer should initiate dialogues on this topic to better understand patients' choices with regard to treatment options.

Occupational physical activity and breast cancer risk in the upper Cape Cod cancer incidence study

BACKGROUND

In several epidemiological studies, breast cancer risk has been reduced among women who reported high levels of occupational or leisure-time physical activity. We used data from a population-based case control study to evaluate the effect of occupational physical activity on breast cancer risk.

METHODS

Two hundred-thirty three incident cases of breast cancer and 670 controls or their next of kin were interviewed for information on breast cancer risk factors and a complete job history. Physical activity level of jobs were classified using a Department of Labor rating scheme. We calculated adjusted odds ratios for light and medium/heavy activity jobs compared to sedentary jobs.

RESULTS

Odds ratios for women who held medium/heavy jobs for less than 10 years and more than ten years were, respectively, 0.7 (95% CI = 0.4,1.3) and 1.7 (95% CI = 0.9,3.3).

CONCLUSIONS

In these data there was no evidence that holding a job of medium/heavy activity reduced breast cancer risk. The study was limited by misclassification inherent in the occupational exposure scheme and by the lack of information on leisure time physical activity. The modest risk increase for subjects holding a medium/heavy job for at least 10 years probably represents either confounding or random variation.

The Working Healthy Project: a worksite health-promotion trial targeting physical activity, diet, and smoking

Worksites are a key channel for delivery of interventions designed to reduce chronic disease among adult populations. Although some evaluations of worksite physical-activity interventions have been conducted, to date very few randomized trials of worksite health promotion have included the goal of increasing physical-activity levels as part of a comprehensive multiple risk factor approach to worksite health promotion. This article presents the results regarding behavior change found among the cohort of 2055 individuals who completed three health-behavior assessments as part of their worksites' participation in The Working Healthy Project (WHP), a multiple risk factor intervention implemented in 26 manufacturing worksites. In this study, a randomized matched-pair design was used. Fifty-one percent (n = 2,761) of the employees who completed the baseline assessment also completed the interim survey. Eighty-three percent of those who completed the interim assessment also completed the final survey. The WHP intervention targeted smoking, nutrition, and physical activity. At baseline, 38% of the sample reported engaging in regular exercise, and subjects reported consuming an average of 2.7 servings of fruits and vegetables per day, 7.9 grams of fiber per 1000 kilocalories, and 35.4% calories from fat per day; 28% of the sample were smokers. By the time of both the interim (intervention midpoint) and final (end of intervention) assessments, participants in the intervention condition had significantly increased their exercise behavior, compared with the control condition. There was also increased consumption of fruits and vegetables and fiber in the intervention condition by the time of the final assessment, compared with the control condition. No differences by condition were found with regard to percentage of calories from fat consumed or smoking cessation. These results suggest that among a cohort of participants in a worksite health promotion study, there were significant health behavior changes across two risk factors over time. These data suggest that further investigation of multiple risk factor worksite health promotion is warranted, particularly with a focus on ways to increase participation in these programs and to diffuse intervention effects throughout the entire workforce.

Breast cancer and occupational exposures in women in Finland

BACKGROUND

The etiology of breast cancer is not fully understood. Environmental and occupational exposures may contribute to breast cancer risk.

METHODS

We linked 324 job titles from the 1970 census of 892,591 Finnish women with incidence of breast cancer (23,638 cases) during 1971-1995. We converted job titles to 31 chemical and two ergonomic agents through a measurement-based, period-specific, national job-exposure matrix. Poisson regression models were fit to the data, with adjustment for birth cohort, follow-up period, socioeconomic status, mean number of children, mean age at first delivery, and turnover rate.

RESULTS

For premenopausal breast cancer, medium/high level of occupational exposure to ionizing radiation was associated with a standardized incidence ratio (SIR) of 1.3 (95% confidence interval (CI) 0.7-2.5; trend P = 0.03). For postmenopausal breast cancer, we found on SIR of 1.2 (1.1-1.3) for low level and 1.4 (1.1-1.8) for medium/high level of ionizing radiation (trend P = 0.001); and an SIR 1.3 (1.1-1.7) for medium/high levels of both asbestos and man-made vitreous fibers. Aromatic hydrocarbon solvents showed a significant trend for a modest excess of postmenopausal breast cancer.

CONCLUSIONS

Our study indicates that occupational exposure to ionizing radiation may be associated with an increased risk of female breast cancer. High-quality studies on environmental and occupational etiology of breast cancer are needed for further elucidation of risk factors.

Asian-Islamic women and breast cancer screening: a socio-cultural analysis

This article explores religious and socio-cultural issues relevant to breast cancer screening practices among older immigrant Asian-Islamic women in the U.S. Some of the Islamic tenets that facilitate breast cancer screening include cleanliness, prevention and individual responsibility in health promotion, diet and eating habits, and exercise, and those that hinder screening practice include gender and modesty considerations and patriarchal marital beliefs. Socio-cultural barriers include patient-physician communication and beliefs about cancer and cancer prevention. Recommendations to increase knowledge and practice of breast cancer screening within a religious and socio-cultural context are provided.

Occupational physical activity and non-Hodgkin's lymphoma

PURPOSE

The purpose of this study was to evaluate the role of physical activity in the development of non-Hodgkin's lymphoma (NHL).

METHODS

Incident NHL cases and population-based controls were identified from three case-control studies conducted in four midwestern states: Iowa, Kansas, Minnesota, and Nebraska. A total of 1177 cases (993 men, 184 women) and 3625 controls (2918 men, 707 women) were interviewed. Usual occupation (all states) and lifetime occupational histories (Iowa and Minnesota only), obtained from interviews, were classified for energy expenditure (EE) and sitting time. Odds ratios (OR) and 95% confidence intervals were calculated comparing moderate and high activity levels with sedentary levels.

RESULTS

There was no evidence of an association between NHL and occupational physical activity measured either by EE or sitting time. Among men, the OR associated with usual occupation moderate and high EE were 1.1 and 1.0, respectively. For sitting time, the OR were also 1.1 and 1.0 for moderate and high activity, respectively. Among women, slight nonsignificant elevations in risk of NHL were observed among the high energy level and high activity sitting categories. The trends were not significant. There was no evidence of confounding or effect modification by vital status, hair dye use, or solvent exposure. Among subjects with lifetime occupational histories, there were no significant increases or trends for cumulative or average EE or sitting time. There was no association between occupational physical activity and NHL.

CONCLUSION

Research on nonoccupational physical activity, which in the U.S. is likely the more important component of daily activity than occupational activity, may still be warranted given the laboratory evidence linking physical activity and immune function, an important factor in the etiology of NHL.

Health psychology: mapping biobehavioral contributions to health and illness

Our evolving understanding of how psychosocial and behavioral factors affect health and disease processes has been marked by investigation of specific relationships and mechanisms underlying them. Stress and other emotional responses are components of complex interactions of genetic, physiological, behavioral, and environmental factors that affect the body's ability to remain or become healthy or to resist or overcome disease. Regulated by nervous, endocrine, and immune systems, and exerting powerful influence on other bodily systems and key health-relevant behaviors, stress and emotion appear to have important implications for the initiation or progression of cancer, HIV, cardiovascular disease, and other illnesses. Health-enhancing and health-impairing behaviors, including diet, exercise, tobacco use, and protection from the sun, can compromise or benefit health and are directed by a number of influences as well. Finally, health behaviors related to being ill or trying to avoid disease or its severest consequences are important. Seeking care and adhering to medical regimens and recommendations for disease surveillance allow for earlier identification of health threats and more effective treatment. Evidence that biobehavioral factors are linked to health in integrated, complex ways continues to mount, and knowledge of these influences has implications for medical outcomes and health care practice.

Physical activity and the primary prevention of cancer

Evidence has been accumulating that suggests that physical activity may help reduce the risk of cancer. Physically active people have been shown to have a decreased rate of all-cancer mortality. The incidence of colon, breast, and perhaps prostate cancer are decreased in more active people when compared with their sedentary peers. Chronic physical activity may decrease tumor risk by its effect on natural immunity, antioxidant defenses, improved energy balance, hormonal changes, or by other unknown mechanisms.

Physical activity and women in the United States: an overview of health benefits, prevalence, and intervention opportunities

Despite decades of physical activity research and interventions conducted on men, very little is known about the patterns of physical activity among US women. Rates from several national surveys show much lower rates of physical activity for women than for men. Among women, rates may vary by socioeconomic status. Studies relating physical activity and experience with heart disease, cancer, osteoporosis, and mental health are discussed. Interventions in the workplace and the community may increase the level of physical activity among US women. A history of not participating in exercise and lack of time for this activity appear to be important constraints for many women. The Surgeon General's Report on physical activity sanctioned future research on specific groups, such as women. Applied research coupled with community and workplace policies that support women's efforts to be more physically active may decrease the rates of some chronic diseases in this population.

Continuity and change in sporting and leisure time physical activities during adolescence

OBJECTIVES

To map the pattern of involvement in physical activities by adolescents at ages 15 and 18 years.

METHODS

Data from a longitudinal cohort study were used. Participants in the Dunedin Multidisciplinary Health and Development Study provided information about their sporting and similar physical activities during the 12 months before study assessments at ages 15 and 18 years.

RESULTS

Total participation time at age 18 was 63% of that reported at age 15. Mean participation time for girls decreased from 7.5 hours a week to 4.3 hours a week (p<0.001) whereas for boys it decreased from 11.7 hours a week to 7.8 hours a week (p<0.001). At both ages, boys spent significantly more time in physical activity than girls. More time in physical activity at age 18 was reported by participants who judged their fitness higher than their peers (odds ratio (OR) 1.7: 1.2, 2.5), those who played sport for their school (OR 1.8: 1.3, 2.4), and those reporting very good self assessed health (OR 1.4: 1.0, 1.8) at age 15. The overall median number of activities decreased from seven at age 15 to three at 18. Boys were involved in more activities at age 15 but there was no sex difference at age 18 in the number of different activities reported.

CONCLUSION

Although involvement in school sporting activities and high levels of fitness in mid-adolescence may protect against marked reductions in physical activity in late adolescence, social and organisational factors are also likely to be important. There is a need for innovative approaches to health promotion which will encourage adolescents to maintain higher levels of physical activity after they leave school.

Quality of reviews in epidemiology

OBJECTIVES

This study examined the quality of recent reviews in epidemiology.

METHODS

All 1995 issues of 7 widely read epidemiology journals were searched to identify reviews.

RESULTS

Twenty-nine reviews were identified. Methodology was not specified or incomplete for literature searches in 79% of reviews; the same was true for inclusion criteria in 83% and for combining studies in 62%. More than 60% of the reviews were not methodologically systematic.

CONCLUSIONS

There is a need to improve the quality of review papers in epidemiology. If systematic methodology were followed more frequently, epidemiologic science and its application could be improved.

Recreational and occupational physical activities and risk of breast cancer

Physical activity has been hypothesized to reduce breast cancer risk, but an inverse association has not been consistently reported. In this review, we critically evaluate for coherence, validity, and bias the epidemiologic studies on recreational or occupational physical activity, discuss the biologic plausibility of the association, and identify areas for future research. Results from seven of nine studies suggest that higher levels of occupational physical activity may be associated with a reduction in risk, at least among a subgroup of women. Eleven of 16 investigations on recreational exercise reported a 12%-60% decrease in risk among premenopausal and postmenopausal women, although a dose-response trend was not evident in most of the studies. The reduction in risk associated with exercise was more likely to be observed in case-control studies than in cohort studies. Most investigations incompletely assessed physical activity, which contributed to conflicting findings on the optimal time period, duration, frequency, or intensity of activity to minimize risk. Physical activity may exert its effects through changes in menstrual characteristics, reduced body size, or alterations in immune function. In summary, most epidemiologic studies of physical activity reported a reduction in the risk of breast cancer among physically active women. Future research studies should focus on using a cohort design to rule out recall bias as a possible explanation for the decrease in risk associated with exercise, on improving assessment of lifetime physical activity from all sources to clarify whether there is a dose-response relation or an optimal time period, duration, frequency, or intensity of activity, and on elucidating the underlying mechanisms for the inverse association.

Methodological aspects of physical activity assessment in epidemiological studies

A range of epidemiological studies conducted over the past decades has produced strong support for the view that lack of physical activity is associated with increased risks of several chronic diseases, such as cardiovascular disease, diabetes mellitus, cancer, etc. Much is still unknown about the type and degree of activity that is required to influence the risk of specific diseases. Furthermore, physical activity can act as a confounder in relationships between other exposure variables (e.g. diet) and disease. Thus, the measurement of physical activity in epidemiological studies is of great importance. The questionnaire is the most frequently used method in epidemiological research. Before using a questionnaire on a large scale, validity and reproducibility should be assessed in a representative population. Some practical and methodological aspects of physical activity validation studies are described, together with the possible implications of the results.

The epidemiology of physical activity and cancer

Experimental studies in animals and epidemiological studies in human populations support an inverse association between exercise and the development of cancer. Physical activity has been shown to be protective against the development of breast and colon cancer and may also be important for other kinds of cancer such as that of the prostate. The proposed biological mechanisms for the physical activity--cancer association include exercise's effect on immune function, transit time of digestion, hormones, and body fat. There has been little research on physical activity and the effect on progression of cancer, although there are studies to suggest that it may slow the clinical course of the disease. Furthermore, exercise may be beneficial in the treatment of cancer through mood elevation, decreased loss of lean tissue, and increased quality of life. Much is still to be learned about the effect of exercise on cancer. The intensity, duration, frequency, and type of exercise that is relevant need to be clarified. As well, the time period during life when exercise is important has not been determined. It seems reasonable to conclude that exercise, a modifiable risk factor, is beneficial in preventing certain forms of cancer. Public health interventions may hold promise for cancer prevention.

Human activities that may lead to high inhaled intake doses in children aged 6-13

This paper focuses on possible activities of children aged 6-13 that may make them susceptible to high hourly intake doses of ozone (O(3)) air pollution. Data from an O(3) exposure modeling exercise indicates that relatively few hours can account for a significant amount of the total cumulative ozone intake dose (D(I)(T)) received in a year. While O(3) concentration levels affected the hourly intake dose (D(Ih)) more than breathing rate (V ̇ (E)), there was a distinct and significant relationship between V ̇ (E) and D(Ih) when hours in a year were stratified by concentration levels. By investigating the V ̇ (E) levels associated with high dose hours, it appears that activities with an hourly V ̇ (E) rate of between 25 and 45 l/min can lead to high intake doses of O(3). The exercise literature was reviewed to ascertain which activities could lead to that range of V ̇ (E)'s and be sustained by children for 1 h. A list of such activities was developed. If an analyst is interested only in modeling high D(Ih) hours for children aged 6-13, an efficient approach might be to focus on those activities and estimate D(I)(T) for the other hours in an aggregated manner.

Risk factors, lifetime risk, and age at onset of breast cancer

PURPOSE

We evaluated the relationship between exposure variables and both lifetime risk and mean age at diagnosis of breast cancer in subjects from the Adventist Health Study who developed breast cancer before the age of 91 years.

METHODS

Multiple decrement life-table analysis was used. This study provided data from 20,341 women followed for 6 years.

RESULTS

In the total population, 30-year-old women with a parental history of any cancer or a maternal history of breast cancer had, respectively, 72% (P < 0.002) and 98% (P < 0.03) higher lifetime risks of breast cancer. Thirty-year-old women who had their first delivery after age 24 years or body mass indices above the 50th percentile had, respectively, 53% (P < 0.007) or 57% (P = 0.01) greater lifetime risk of breast cancer. Women who exercised infrequently had a 27% higher life-time risk (P = 0.09) and an age at diagnosis of breast cancer 6.6 years younger (P < 0.005) than other women.

CONCLUSIONS

Standard risk factors account for substantial increases in lifetime risk of breast cancer and may be associated with differences in age at diagnosis.