Social networks and survival after breast cancer diagnosis

INTRODUCTION

Evidence has been inconsistent regarding the impact of social networks on survival after breast cancer diagnosis. We prospectively examined the relation between components of social integration and survival in a large cohort of breast cancer survivors.

METHODS

Women (N=4,589) diagnosed with invasive breast cancer were recruited from a population-based, multi-center, case-control study. A median of 5.6 years (Interquartile Range 2.7-8.7) after breast cancer diagnosis, women completed a questionnaire on recent post-diagnosis social networks and other lifestyle factors. Social networks were measured using components of the Berkman-Syme Social Networks Index to create a measure of social connectedness. Based on a search of the National Death Index, 552 deaths (146 related to breast cancer) were identified. Adjusted hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards regression.

RESULTS

Higher scores on a composite measure of social connectedness as determined by the frequency of contacts with family and friends, attendance of religious services, and participation in community activities was associated with a 15-28% reduced risk of death from any cause (p-trend=0.02). Inverse trends were observed between all-cause mortality and frequency of attendance at religious services (p-trend=0.0001) and hours per week engaged in community activities (p-trend=0.0005). No material associations were identified between social networks and breast cancer-specific mortality.

CONCLUSIONS

Engagement in activities outside the home was associated with lower overall mortality after breast cancer diagnosis.

Psychosocial determinants of mammography follow-up after receipt of abnormal mammography results in medically underserved women

This article targets the relationship between psychosocial determinants and abnormal screening mammography follow-up in a medically underserved population. Health belief scales were modified to refer to diagnostic follow-up versus annual screening. A retrospective cohort study design was used. Statistical analyses were performed examining relationships among sociodemographic factors, psychosocial determinants, and abnormal mammography follow-up. Women with lower mean internal health locus of control scores (3.14) were two times more likely than women with higher mean internal health locus of control scores (3.98) to have inadequate follow-up (OR=2.53, 95% CI=1.12-5.36). Women with less than a high school education had lower cancer fatalism scores than women who had completed high school (47.5 vs. 55.2, p-value=.02) and lower mean external health locus of control scores (3.0 vs. 5.3) (p-value<.01). These constructs have implications for understanding mammography follow-up among minority and medically underserved women. Further comprehensive study of these concepts is warranted.

Abstract 876: Bilateral oophorectomy and breast cancer: Confounding by non-malignant indications for surgery

Background: Bilateral oophorectomy at early ages (&lt;40 years) is recognized to lower breast cancer risk. Among U.S. women, oophorectomy is often performed with hysterectomy for benign conditions such as endometriosis and uterine fibroids. We aimed to determine whether a prior diagnosis of endometriosis or fibroids would attenuate breast cancer risk reductions conferred by bilateral oophorectomy.

Methods: We analyzed data from a population-based case-control study of women aged 50-79 living in Wisconsin, Massachusetts and New Hampshire during 1992-1995. Incident cases (N=5,068) of invasive breast cancer were identified from state-wide tumor registries. Age-matched controls (N=5,246) were selected from driver's license and Medicare beneficiary lists. Reproductive and medical history (including physician diagnosis of endometriosis or uterine fibroids) and lifestyle factors were self-reported during structured telephone interviews. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using logistic regression and adjusted for reproductive history, exogenous hormone use, body mass index, and family history of breast cancer. Statistical interaction was assessed by including cross-product terms in regression models.

Results: Overall, 83% of cases and 78% of controls participated. Women with bilateral oophorectomy at ages ≤40 years had 0.76 times the odds of breast cancer (95% CI: 0.63, 0.92) compared to women with intact ovaries and uterus. Self-reported history of endometriosis (OR=0.86; 95% CI: 0.71, 1.05) and uterine fibroids (OR=1.09; 95% CI: 0.98, 1.21) were not significantly associated with breast cancer risk in multivariate models. However, in analyses restricted to women who reported a hysterectomy with bilateral oophorectomy (N=991 cases, 1,081 controls), a diagnosis of endometriosis was associated with decreased breast cancer risk (OR=0.72; 95% CI: 0.54, 0.98), while uterine fibroids were positively associated with breast cancer (OR=1.36; 1.13, 1.63). Among women with intact ovaries and uterus (N=3,188 cases, 3,275 controls), neither endometriosis (OR=1.18; 95% CI: 0.79, 1.77) nor fibroids (OR=1.12; 95% CI: 0.93, 1.35) appeared to be associated with breast cancer risk. The interaction test for breast cancer risk according to a prior history of endometriosis and gynecologic surgery status was statistically significant (p-interaction=0.02); the cross-product term for fibroids and hysterectomy with bilateral oophorectomy was not (p-interaction=0.2).

Conclusions: In this study, the association between self-reported endometriosis and breast cancer risk was modified by gynecologic surgery status. If replicated, the apparent protective effect of endometriosis on breast cancer risk only among women who undergo gynecologic surgery could be a result of prior treatment with agents such as NSAIDs or gonadatropin-releasing hormone agonists.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 876.

Sleep duration and obesity in a population-based study

BACKGROUND

Previous studies have demonstrated an association between sleep duration and obesity, but few population-based studies have examined the association. We examined the relationship between recent and usual lifetime sleep duration with the odds of obesity in 5549 women that participated in a population-based telephone survey.

METHODS

The structured telephone interview included questions on usual sleep duration in adult life and the recent past, as well as height and weight and other demographic and lifestyle characteristics. We examined odds of overweight (BMI: 25-29.9 kg/m(2)), obesity (BMI: 30-39.9 kg/m(2)) and extreme obesity (BMI: 40 kg/m(2)) according to reported sleep duration.

RESULTS

Compared to women who slept 7-7.9h per night, women who slept an average of <6h per night in the recent past had significantly greater odds of obesity (Odds Ratio [OR]: 1.89; 95% Confidence Interval [CI]: 1.45-2.47) and extreme obesity (OR: 3.12; CI: 1.70-5.75), adjusting for potential confounding factors. Weaker associations were noted for short lifetime sleep duration. Current short sleep (<7h) was associated with greater odds of obesity (30 kg/m(2)) in those reporting less than 7h (OR: 1.59; 95% CI: 0.93-2.78) and in those reporting 8 or more hours (OR: 1.75; 95% CI: 1.33-2.32) of sleep throughout adult life.

CONCLUSIONS

Current short sleepers were more likely to be obese regardless of their usual sleep duration earlier in life. These findings do not support the hypothesis that sleep duration is a causal factor in obesity.

The "Got D'ViBE?" study: an inter-institutional project assessing vitamin D and mammographic breast density

A multi-institutional collaboration was forged to implement a study of the relationship between Vitamin D and breast density among medically underserved women. This effort resulted in techniques to measure vitamin D levels, breast density, and sunlight exposure. Outcomes from this collaboration may provide insight to researchers conducting similar investigations.

Association of COMT haplotypes and breast cancer risk in caucasian women

Catechol-O-methyl transferase (COMT) is an important estrogen-metabolizing enzyme, and common genetic variants in this gene could affect breast cancer risk. We conducted a large population-based case control study in Massachusetts, New Hampshire, and Wisconsin to examine six strategically selected COMT haplotype-tagging (ht) single nucleotide polymorphism (SNPs), including the val158met polymorphism (rs4680), in relation to breast cancer risk. Analyses were based on 1,655 Caucasian women with invasive breast cancer and 1,470 Caucasian controls. None of the six individual SNPs were associated with breast cancer risk. The global test for haplotype associations was nonsignificant (p-value=0.097), although two uncommon haplotypes present in 6% of the study population showed statistically significant inverse associations with risk. These results suggest that genetic variation in COMT has no significant association with breast cancer risk among Caucasian women.

Dietary carotenoids and the risk of invasive breast cancer

Certain classes of vitamins and nutrients found in fruits and vegetables have been of particular interest in relation to cancer prevention, owing to their potential anticarcinogenic properties. We examined the association between certain fruits, vegetables, carotenoids, and vitamin A and breast cancer risk in a large population-based case-control study of women residing in the states of Massachusetts, New Hampshire and Wisconsin. The study was comprised of 5,707 women with incident invasive breast cancer (2,363 premenopausal women and 3,516 postmenopausal women) and 6,389 population controls (2,594 premenopausal women and 3,516 postmenopausal women). In an interview, women were asked about their intake of carotenoid rich fruits and vegetables 5 years prior to a referent date. An inverse association observed among premenopausal women was for high levels of vitamin A (OR: 0.82, 95% CI: 0.68-0.98, p for trend = 0.01), beta-carotene (OR: 0.81, 95% CI 0.68-0.98, p for trend = 0.009), alpha-carotene (OR: 0.82, 95% CI: 0.68-0.98, p for trend = 0.07) and lutein/zeaxanthin (OR: 0.83, 95% CI 0.68-0.99, p for trend = 0.02). An inverse association was not observed among postmenopausal women. Among premenopausal women who reported ever smoking, these results were stronger than among never smokers, although tests for interaction were not statistically significant. Results from this study are comparable to previous prospective studies, and suggest that a high consumption of carotenoids may reduce the risk of premenopausal but not postmenopausal breast cancer, particularly among smokers.

Estrogen exposure, metabolism, and enzyme variants in a model for breast cancer risk prediction

Estrogen is a well-known risk factor for breast cancer. Current models of breast cancer risk prediction are based on cumulative estrogen exposure but do not directly reflect mammary estrogen metabolism or address genetic variability between women in exposure to carcinogenic estrogen metabolites. We are proposing a mathematical model that forecasts breast cancer risk for a woman based on three factors: (1) estimated estrogen exposure, (2) kinetic analysis of the oxidative estrogen metabolism pathway in the breast, and (3) enzyme genotypes responsible for inherited differences in the production of carcinogenic metabolites. The model incorporates the main components of mammary estrogen metabolism, i.e. the conversion of 17β-estradiol (E₂) by the phase I and II enzymes cytochrome P450 (CYP) 1A1 and 1B1, catechol-O-methyltransferase (COMT), and glutathione S-transferase P1 (GSTP1) into reactive metabolites, including catechol estrogens and estrogen quinones, such as E₂-3,4-Q which can damage DNA. Each of the four genes is genotyped and the SNP data used to derive the haplotype configuration for each subject. The model then utilizes the kinetic and genotypic data to calculate the amount of E₂-3,4-Q carcinogen as ultimate risk factor for each woman. The proposed model extends existing models by combining the traditional “phenotypic” measures of estrogen exposure with genotypic data associated with the metabolic fate of E₂ as determined by critical phase I and II enzymes. Instead of providing a general risk estimate our model would predict the risk for each individual woman based on her age, reproductive experiences as well as her genotypic profile.

Meat consumption, heterocyclic amines, NAT2, and the risk of breast cancer

Meat consumption and heterocyclic amine (HCA) intake have been inconsistently associated with breast cancer risk in epidemiologic studies. Genetic variation in N-acetyltransferase2 (NAT2) has been suggested to modify the association of meat intake with breast cancer through its influence on metabolism of HCAs. We examined associations between meat intake, HCA exposure, acetylator genotype, and breast cancer risk in a case-control study of 2,686 case women and 3,508 controls. Women were asked to report their usual intake, cooking method, and preferred doneness of specific meats. We observed no association between total meat, red meat, or chicken with breast cancer risk. Women who consumed 5 or more servings of meat per week had no increased risk of breast cancer compared to women consuming fewer than 2 servings per week (OR = 0.99, 95% CI 0.84-1.15). No statistically significant associations with breast cancer were found for individual HCAs or for total estimated mutagenic activity of meat. Results varied modestly according to menopausal status. There were no statistically significant interactions with NAT2 genotype. Results do not support an important association of HCAs with breast cancer risk, although potential biases in case-control studies should be considered.

Body mass index before and after breast cancer diagnosis: associations with all-cause, breast cancer, and cardiovascular disease mortality

BACKGROUND

Factors related to improving outcomes in breast cancer survivors are of increasing public health significance. We examined postdiagnosis weight change in relation to mortality risk in a cohort of breast cancer survivors.

METHODS

We analyzed data from a cohort of 3,993 women with ages 20 to 79 years living in New Hampshire, Massachusetts, or Wisconsin with invasive nonmetastatic breast cancers diagnosed in 1988 to 1999 identified through state registries. Participants completed a structured telephone interview 1 to 2 years after diagnosis and returned a mailed follow-up questionnaire in 1998 to 2001 that addressed postdiagnosis weight and other factors. Vital status information was obtained from the National Death Index through December 2005. Hazard ratios and 95% confidence intervals were estimated from Cox proportional hazards models and adjusted for prediagnosis weight, age, stage, smoking, physical activity, and other important covariates.

RESULTS

During an average 6.3 years of follow-up from the postdiagnosis questionnaire, we identified 421 total deaths, including 121 deaths from breast cancer and 95 deaths from cardiovascular disease. Increasing postdiagnosis weight gain and weight loss were each associated with greater all-cause mortality. Among women who gained weight after breast cancer diagnosis, each 5-kg gain was associated with a 12% increase in all-cause mortality (P = 0.004), a 13% increase in breast cancer-specific mortality (P = 0.01), and a 19% increase in cardiovascular disease mortality (P = 0.04). Associations with breast cancer mortality were not modified by prediagnosis menopausal status, cigarette smoking, or body mass index.

CONCLUSION

These findings suggest that efforts to minimize weight gain after a breast cancer diagnosis may improve survival.

Exposure to breast milk in infancy and risk of breast cancer

Early life exposures, such as being breastfed in infancy, may influence the risk of breast cancer in adulthood. We evaluated the risk of breast cancer in relation to ever having been breastfed in infancy among 9,442 women who participated in a population-based, case-control study. Cases were identified through cancer registries in three states (Massachusetts, New Hampshire, and Wisconsin); controls were identified through statewide drivers' license lists or medicare lists. Data on known and suspected risk factors were obtained through telephone interview. We used unconditional logistic regression to assess the relation of breast cancer with ever having been breastfed and with breastfeeding duration (available for only 19% of breastfed women) in premenopausal women (1,986 cases and 1,760 controls) and postmenopausal women (2,600 cases and 2,493 controls). We found no evidence that ever having been breastfed in infancy was associated with breast cancer risk in either premenopausal women (odds ratio [OR] = 0.96; 95% confidence interval [CI] = 0.83-1.10) or postmenopausal women (OR = 0.98; 95% CI = 0.87-1.10). The association did not differ according to breast cancer stage, mother's history of breast cancer, or any other reproductive factor assessed. Likewise, we found no association between breastfeeding duration and risk of breast cancer. Our results did not support the hypothesis that exposure to breast milk in infancy influences the risk of adult breast cancer.

Association of CYP1B1 haplotypes and breast cancer risk in Caucasian women

CYP1B1 is a key enzyme involved in estrogen metabolism and may play an important role in the development and progression of breast cancer. In a population-based case-control study, we examined eight CYP1B1 haplotype-tagging single nucleotide polymorphisms in relation to invasive breast cancer risk. Analyses were based on 1,655 cases and 1,470 controls; all women were Caucasian. Among the individual single nucleotide polymorphisms, one (rs9341266) was associated with increased risk of breast cancer (P(trend) = 0.021), although the association was no longer significant after adjusting for multiple tests. A marginally significant haplotype effect was identified (P(global) = 0.015), with significant associations identified for 2 uncommon haplotypes comprising 4% of the controls. Results suggest that genetic variation in CYP1B1 has at most a minor influence on breast cancer susceptibility among Caucasian women.

Tea consumption and risk of breast cancer

OBJECTIVE

The purpose of our study was to examine the association of regular tea consumption with the risk of breast cancer in a large population-based case-control study from the United States.

METHODS

Five thousand and eighty-two women with incident breast cancer between the ages of 20 and 74 years old from population-based cancer registries in Wisconsin, Massachusetts, and New Hampshire and 4,501 age-matched controls from lists of licensed drivers and Medicare beneficiaries completed a structured telephone interview that included information on usual tea consumption 5 years prior to the interview and other breast cancer risk factors. Logistic regression was used to obtain covariate-adjusted odds ratios and 95% confidence intervals associated with quantities of tea consumed.

RESULTS

Tea consumption was not related to breast cancer risk overall (P for trend = 0.18). However, when stratified by age, an inverse association was observed among women less than 50 years: those consuming three or more cups per day had a 37% reduced breast cancer risk when compared with women reporting no tea consumption (age and study site-adjusted odds ratios, 0.63; 95% confidence intervals, 0.44-0.89; P = 0.01) with a significant test for trend (P = 0.01). The inverse association noted among younger women was consistent for in situ and invasive breast cancer, and for ductal and lobular breast cancer. All results were unchanged after adjustment for established risk factors.

CONCLUSION

We observed evidence to support a potential beneficial influence for breast cancer associated with moderate levels of tea consumption (three or more cups per day) among younger women. Further research is needed to confirm this association.

Childbearing recency and modifiers of premenopausal breast cancer risk

The purpose of this study was to examine the risk of premenopausal breast cancer for women in relation to childbearing recency and whether this association differs by breast-feeding history and/or the amount of weight gained during pregnancy. This analysis was based on data from a population-based case-control study composed of 1,706 incident cases of invasive breast cancer and 1,756 population controls from Wisconsin, New Hampshire, and Massachusetts. In a telephone interview conducted from 1996 to 2001, information was gathered on established breast cancer risk factors, as well as reproductive history, including amount of weight gained during the last full-term pregnancy and whether the child was breast-fed. Unconditional logistic regression was used to estimate odds ratios and Wald 95% confidence intervals for the risk of breast cancer. When compared with nulliparous women, women that had given birth within the past 5 years before breast cancer diagnosis in the cases or a comparable period in controls had a nonsignificant 35% increased risk of invasive breast cancer (odds ratio, 1.35; 95% confidence interval, 0.90-2.04), adjusting for age and known breast cancer risk factors (Ptrend = 0.14). We did not find a significant interaction with breast-feeding (Pinteraction = 0.30) or pregnancy weight gain (Pinteraction = 0.09).

Family history is a significant risk factor for pancreatic cancer: results from a systematic review and meta-analysis

Epidemiologic evidence suggests a family history of pancreatic cancer (PC) is a risk factor for the disease, yet the magnitude of risk varies between studies. We performed a systematic review of studies that quantified familial risks of PC, and through a meta-analysis, obtained more precise estimates of familial risk. A MEDLINE search identified published studies that reported relative risks (RR) of PC associated with a family history of the disease. A random effects model was used to summarize study-specific RRs and 95% confidence intervals (CI). Sensitivity and sub-group analyzes were performed. Seven case-control and two cohort studies involving 6,568 PC cases were identified. There was no evidence of statistical heterogeneity between studies (I(2) = 0%; P = 0.483). Results from case-control (RR = 2.82; 95% CI: 1.99-3.66) and cohort (RR = 1.62; 95% CI: 1.28-1.97) studies showed a significant increase in PC risk associated with having an affected relative, with an overall summary RR = 1.80 (95% CI: 1.48-2.12). Similar RR were observed for early (RR = 2.69; 95% CI: 0.56-4.82) and later (RR = 3.41; 95% CI: 0.79-6.03) onset disease in the index case. Data was too sparse to generate an overall summary RR based on the number or type of affected relatives. Individuals with a family history of PC have nearly a two-fold increased risk for developing PC compared to those without such a history. Families with two or more PC cases may benefit from comprehensive risk assessment that involves collection of detailed family history information and data regarding various risk factors for PC, especially smoking history. Those at highest risk may be referred to screening programs and studies; these are important steps toward early detection and greater odds of surviving this disease.

Proportion of invasive breast cancer attributable to risk factors modifiable after menopause

A number of breast cancer risk factors are modifiable later in life, yet the combined impact of the population changes in these risk factors on breast cancer incidence is not known to have been evaluated. The population attributable risk (PAR) associated with individual risk factors and the summary PAR for sets of modifiable and nonmodifiable risk factors were estimated by using data on 3,499 invasive breast cancer cases and 4,213 controls from a population-based study in Wisconsin, Massachusetts, and New Hampshire, conducted from 1997 to 2001. The summary PAR for factors modifiable after menopause, including current postmenopausal hormone use, recent alcohol consumption, adult weight gain, and recent recreational physical activity, was 40.7%. Of the individual modifiable factors, the highest PARs were observed for weight gain (21.3%) and recreational physical activity (15.7%), which together showed a summary PAR of 33.6%. The summary PAR for factors not modifiable after menopause, including family history of breast cancer, personal history of benign breast disease, height at age 25 years, age at menarche, age at menopause, age at first birth, and parity, was 57.3%. These findings suggest that a substantial fraction of postmenopausal breast cancer may be avoided by purposeful changes in lifestyle later in life.

Inverse association of NSAID use and ovarian cancer in relation to oral contraceptive use and parity

We examined the association between non-steroidal anti-inflammatory drug (NSAID) use and ovarian cancer by potential effect modifiers, parity and oral contraceptive use, in a population-based case–control study conducted in Wisconsin and Massachusetts. Women reported prior use of NSAIDs and information on risk factors in a telephone interview. A total of 487 invasive ovarian cancer cases and 2653 control women aged 20–74 years were included in the analysis. After adjustment for age, state of residence and other covariates, ever use of NSAIDs was inversely associated with ovarian cancer in never users of oral contraceptives (odds ratio (OR)=0.58, 95% confidence interval (CI) 0.42–0.80) but not for ever users (OR=0.98, 95% CI 0.71–1.35) (P-interaction=0.03). A reduced risk with NSAID use was also noted in nulliparous women (OR=0.47, 95% CI 0.27–0.82) but not among parous women (OR=0.81, 95% CI 0.64–1.04) (P-interaction=0.05). These results suggest that use of NSAIDs were beneficial to women at greatest risk for ovarian cancer.

Prediagnostic use of hormone therapy and mortality after breast cancer

BACKGROUND

A few studies have observed reduced breast cancer mortality in women who used hormone therapy before diagnosis. Due to the high prevalence of past and current hormone use, it is important to investigate whether these preparations are related to breast cancer mortality.

METHODS

To evaluate the influence of prediagnostic use of hormone therapy on breast cancer mortality, a prospective cohort of 12,269 women ages 50 years or more diagnosed with incident invasive breast cancer and residents of Wisconsin, Massachusetts, or New Hampshire were enrolled in three phases beginning in 1988. They were followed for death until December 31, 2005, using the National Death Index. Cumulative mortality and multivariable adjusted hazard rate ratios for breast cancer and other mortality causes were calculated for women according to any hormone therapy use, and for exclusive use of estrogen or estrogen-progestin (EP).

RESULTS

During an average 10.3 years of follow-up, 1,690 deaths from breast cancer were documented. Cumulative mortality from breast cancer was lower among hormone therapy users, specifically current users at the time of diagnosis, and EP users, compared with nonusers. Adjusted survival varied by type and duration of hormone therapy before diagnosis. A reduced risk of death from breast cancer was associated with EP preparations (hazard rate ratio, 0.73; 0.59-0.91) and with > or =5 years of EP use (0.60; 0.43-0.84). No association was observed for women who were former or current users of E-alone preparations.

CONCLUSIONS

Although use of combined EP preparations increases breast cancer risk, in this study, use of these hormones before diagnosis was associated with reduced risk of death after a breast cancer diagnosis. The better survival among users, particularly of EP, persisted after adjustment of screening, stage, and measured confounders.

Cigarette smoking and risk of breast carcinoma in situ

BACKGROUND

Although the associations with cigarette smoking have been explored extensively for invasive breast cancer, the relation to in situ cancer has not previously been examined in depth.

METHODS

We analyzed data from a population-based case-control study of women living in Wisconsin, Massachusetts, and New Hampshire. Eligible cases of incident breast carcinoma in situ were reported to statewide registries in 1997-2001 (n = 1878); similarly aged controls (n = 8041) were randomly selected from population lists. Smoking history and other risk factor information were collected through structured telephone interviews. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated from logistic regression models adjusting for potential confounders.

RESULTS

In multivariate models, the OR for breast carcinoma in situ among current smokers was 0.8, compared with never-smokers (95% CI = 0.7-1.0). Risk estimates increased towards the null with greater time since smoking cessation. Odds ratios were also less than 1.0 among women who initiated smoking in adolescence (OR = 0.8) or after a full-term birth (OR = 0.7), relative to women who never smoked. The reduced odds ratios associated with current smoking were strongest among women with annual screening mammograms (OR = 0.7; 95% CI = 0.6-0.9). Odds ratios were not less than 1.0 among current smokers without a recent screening mammogram (1.3; 0.9-2.0).

CONCLUSIONS

Our findings suggest an inverse association between current smoking and risk of breast carcinoma in situ among women undergoing breast cancer screening.

Physical activity and survival after diagnosis of invasive breast cancer

Previous studies suggest that increased physical activity may lower the risk of breast cancer incidence, but less is known about whether levels of physical activity after breast cancer diagnosis can influence survival. We prospectively examined the relation between postdiagnosis recreational physical activity and risk of breast cancer death in women who had a previous invasive breast cancer diagnosed between 1988 and 2001 (at ages 20-79 years). All women completed a questionnaire on recent postdiagnosis physical activity and other lifestyle factors. Among 4,482 women without history of recurrence at the time of completing the questionnaire, 109 died from breast cancer within 6 years of enrollment. Physical activity was expressed as metabolic equivalent task-hours per week (MET-h/wk); hazard ratios (HR) and 95% confidence intervals (95% CI) were estimated using Cox proportional hazards regression. After adjusting for age at diagnosis, stage of disease, state of residence, interval between diagnosis and physical activity assessment, body mass index, menopausal status, hormone therapy use, energy intake, education, family history of breast cancer, and treatment modality compared with women expending <2.8 MET-h/wk in physical activity, women who engaged in greater levels of activity had a significantly lower risk of dying from breast cancer (HR, 0.65; 95% CI, 0.39-1.08 for 2.8-7.9 MET-h/wk; HR, 0.59; 95% CI, 0.35-1.01 for 8.0-20.9 MET-h/wk; and HR, 0.51; 95% CI, 0.29-0.89 for > or =21.0 MET-h/wk; P for trend = 0.05). Results were similar for overall survival (HR, 0.44; 95% CI, 0.32-0.60 for > or =21.0 versus <2.8 MET-h/wk; P for trend <0.001) and were similar regardless of a woman's age, stage of disease, and body mass index. This study provides support for reduced overall mortality and mortality from breast cancer among women who engage in physical activity after breast cancer diagnosis.

Timing is everything: methodologic issues locating and recruiting medically underserved women for abnormal mammography follow-up research

OBJECTIVES

Recruiting underserved women in breast cancer research studies remains a significant challenge. We present our experience attempting to locate and recruit minority and medically underserved women identified in a Nashville, Tennessee public hospital for a mammography follow-up study.

STUDY DESIGN

The study design was a retrospective hospital-based case-control study.

METHODS

We identified 227 women (88 African-American, 65 Caucasian, 36 other minority, 38 race undocumented in the medical record) who had undergone screening mammography and received an abnormal result during 2003-2004. Of the 227 women identified, 159 women were successfully located with implementation of a tracking protocol and more rigorous attempts to locate the women using online directory assistance and public record search engines. Women eligible for the study were invited to participate in a telephone research survey. Study completion was defined as fully finishing the telephone survey.

RESULTS

An average of 4.6 telephone calls (range 1-19) and 2.7 months (range 1-490 days) were required to reach the 159 women contacted. Within three contact attempts, more cases were located than controls (61% cases vs. 49% controls, p=0.03). African-American women cases were four times likely to be recruited than African-American controls, (OR, 4.07; 95% CI, 1.59-10.30) (p=0.003). After 3 months of effort, we located 67% of African-American women, 63% of Caucasian women, and 56% of other minorities. Ultimately, after a maximum of 12 attempts to contact women, 77% of African-American women and 71% of Caucasian women were eventually found. Of these, 59% of African-American women, 69% Caucasian women, and 50% other minorities were located and completed the study survey for an overall response rate of 59%, 71%, and 47% respectively.

CONCLUSIONS

Data collection and study recruitment efforts were more challenging in racial and ethnic minorities. Continuing attempts to contact women may increase minority group study participation but does not guarantee retention or study completion.

Whole-genome amplification of oral rinse self-collected DNA in a population-based case-control study of breast cancer

The availability of large amounts of genomic DNA (gDNA) is the limiting factor for many of the molecular biology assays in genetic epidemiologic studies. Whole-genome amplification using multiple displacement amplification is used to amplify a representative sample of gDNA from small amounts of gDNA to optimize gDNA yield. We collected oral rinse DNA samples through the mail from 3,377 women enrolled in a population-based U.S. breast cancer case-control study and did whole-genome amplification by multiple displacement amplification. Genotyping was done for 66 single nucleotide polymorphisms (SNP) in 18 candidate susceptibility genes using amplified DNA with genomic replicates included for quality control. The concordance rates (percentages of agreement) in 95 quality control replicates of gDNA and amplified DNA for 66 SNPs ranged from 88% to 100% (median, 97%). The average allelic error rate was 0.9%. However, in further analyses based on the full control series (n = 1,492), >60% of the SNPs failed tests for Hardy-Weinberg equilibrium (P < 0.05), with evidence of heterozygote loss in the great majority. Even eliminating the 9% of samples with lower quality or input DNA, tests for Hardy-Weinberg equilibrium indicated persistent allele bias in nearly a third of the SNPs. Whole-genome amplification may introduce substantial allele amplification bias in gDNA collected using a common protocol in population-based epidemiologic studies.

Occupational exposure to electromagnetic field and breast cancer risk in a large, population-based, case-control study in the United States

OBJECTIVE

Our objective was to evaluate women who were occupationally exposed to electromagnetic fields (EMF) and breast cancer risk.

METHODS

Women diagnosed with breast cancer (n=6213) and randomly selected age-matched control subjects (n=7390) provided breast cancer risk factor information and occupational history. A qualified industrial hygienist classified each job for EMF exposure as background, low, medium, or high.

RESULTS

When compared with the referent of background exposure, the odds ratio adjusted for age and state of residence was 1.06 (95% CI=0.99-1.14) for low exposure, 1.09 (95% CI=0.96-1.23) for medium exposure, and 1.16 (95% CI=0.90-1.50) for high exposure.

CONCLUSION

Our findings, taken together with previous epidemiological studies, suggest that exposure to EMF in the workplace may be associated with a slight elevation in breast cancer risk.