Oral contraceptive formulation and risk of breast cancer.

BACKGROUND: While evidence on the association between oral contraceptive (OC) use and breast cancer generally suggests little or no increased risk, the question of whether breast cancer risk varies by OC formulation remains controversial. Few studies have examined this issue because large samples and extensive OC histories are required. STUDY DESIGN: We used data from a multicenter, population-based, case-control investigation. Women aged 35-64 years were interviewed. To explore the association between OC formulation and breast cancer risk, we used conditional logistic regression to derive adjusted odds ratios, and we used likelihood ratio tests for heterogeneity to assess whether breast cancer risk varied by OC formulation. Key OC exposure variables were ever use, current or former use, duration of use and time since last use. To strengthen inferences about specific formulations, we restricted most analyses to the 2282 women with breast cancer and the 2424 women without breast cancer who reported no OC use or exclusive use of one OC. RESULTS: Thirty-eight formulations were reported by the 2674 women who used one OC; most OC formulations were used by only a few women. We conducted multivariable analyses on the 10 formulations that were each used by at least 50 women and conducted supplemental analyses on selected formulations of interest based on recent research. Breast cancer risk did not vary significantly by OC formulation, and no formulation was associated with a significantly increased breast cancer risk. CONCLUSIONS: These results add to the small body of literature on the relationship between OC formulation and breast cancer. Our data are reassuring in that, among women 35-64 years of age, we found no evidence that specific OC formulations increase breast cancer risk.

The Master of Science in clinical epidemiology degree program of the Perelman School of Medicine at the University of Pennsylvania: a model for clinical research training.

An innovative training program to provide clinical research training for clinicians was created in 1979 at the University of Pennsylvania School of Medicine, now the Perelman School of Medicine. The program's principal and continuing aim is to provide trainees mentored experiences and the training needed to become skilled independent investigators able to conduct clinical research and develop academic careers as independent clinical investigators.The authors identify the vision that led to the creation of the master of science in clinical epidemiology (MSCE) degree program and describe today's training program, including administration, oversight, participating faculty, and trainees. They also describe the program's core curriculum, elective options, seminars on ongoing research, training in the responsible conduct of research, professional development activities, and the development and completion of a closely mentored clinical research project.Approximately 35 new trainees enter the two- to three-year program annually. Funding is provided primarily by National Institutes of Health-funded training programs and supplemented by private industry, private foundations, and employee-based benefits. More than 500 individuals have received or are currently receiving training through the MSCE program. A large percentage of former trainees maintain full-time positions in academic medicine today.The authors identify some challenges that have been met and insights regarding funding, faculty, trainees, and curriculum. Ongoing challenges include recruiting trainees from some selected highly paid, procedure-oriented specialties, maintaining sufficient mentors for the continually increasing numbers of trainees, and distinguishing applicants who truly desire a primary research career from others.

Obesity and survival among black women and white women 35 to 64 years of age at diagnosis with invasive breast cancer.

PURPOSE: To evaluate the effect of obesity on survival among black women and white women with invasive breast cancer and to determine whether obesity explains the poorer survival of black women relative to white women. PATIENTS AND METHODS: We observed 4,538 (1,604 black, 2,934 white) women who were 35 to 64 years of age when diagnosed with incident invasive breast cancer between 1994 and 1998. Multivariate Cox regression models were used to examine the effect of body mass index (BMI, in kilograms per square meter) 5 years before diagnosis on risk of death from any cause and from breast cancer. RESULTS: During a median of 8.6 years of follow-up, 1,053 women died (519 black, 534 white), 828 as a result of breast cancer (412 black, 416 white). Black women were more likely to die than white women (multivariate-adjusted relative risk [RR], 1.33; 95% CI, 1.16 to 1.53). Compared with women with BMI of 20 to 24.9 kg/m(2), those who were obese (BMI ≥ 30 kg/m(2)) had a greater risk of all-cause mortality (RR, 1.23; 95% CI, 1.04 to 1.47) and breast cancer-specific mortality (RR, 1.20; 95% CI, 0.99 to 1.46). These associations were observed among white women (all-cause RR, 1.54; 95% CI, 1.21 to 1.96; breast cancer RR, 1.46; 95% CI, 1.11 to 1.92), but not among black women (all-cause RR, 1.03; 95% CI, 0.81 to 1.29; breast cancer RR, 1.02; 95% CI, 0.79 to 1.33). CONCLUSION: Obesity may play an important role in mortality among white but not black patients with breast cancer. It is unlikely that differences in obesity distributions between black women and white women account for the poorer survival of black women.

Oral contraceptive use and survival in women with invasive breast cancer.

BACKGROUND: Oral contraceptives (OC) are widely used in the United States. Although the relation between OC use and breast cancer incidence has been widely studied, the few studies examining associations between OC use prior to breast cancer diagnosis and survival are inconsistent. METHODS: Women with invasive breast cancer participating in the Women's Contraceptive and Reproductive Experiences (CARE) Study, a population-based case-control study (4565 women ages 35-64 years), and the California Teachers Study (CTS) cohort (3929 women ages 28-91 years) were followed for vital status. A total of 1,064 women died in the CARE Study (median follow-up, 8.6 years) and 523 died in the CTS (median follow-up, 6.1 years). Cox proportional hazards regression provided hazard rate ratio estimates [(relative risk, RR)] with 95% confidence intervals (CIs) for risk of death from any cause and from breast cancer. RESULTS: No association was observed for any OC use prior to diagnosis and all-cause mortality [CARE Study: RR = 1.01 (95% CI = 0.86-1.19); CTS: RR = 0.84 (95% CI = 0.67-1.05)]. A decreased risk of all-cause mortality was observed in the CTS among women with more than 10 years of OC use (RR = 0.67, 95% CI = 0.47-0.96); however, no trend of decreasing risk with increasing OC duration was observed (P(trend) = 0.22), and no association was observed in the CARE study. No associations were observed for breast cancer-specific mortality. CONCLUSIONS: OC use is not associated with all-cause or breast cancer-specific mortality among women with invasive breast cancer. IMPACT: These 2 independent studies demonstrated no overall association between OC use and survival among women with breast cancer.

Breast cancer risk and ovariectomy, hysterectomy, and tubal sterilization in the women's contraceptive and reproductive experiences study.

Removal or impairment of ovaries before menopause may affect a woman's breast cancer risk by altering her cumulative exposure to ovarian hormones. The Women's Contraceptive and Reproductive Experiences Study, a population-based, multicenter case-control study of incident invasive breast cancer, recruited women aged 35-64 years (4,490 cases and 4,611 controls) who provided data on ovariectomy, hysterectomy, and tubal sterilization during in-person interviews. Controls were frequency-matched to cases by age, race, and study site. Unconditional logistic regression analysis was used. Women who had not undergone premenopausal reproductive surgery were the referent group. Bilateral ovariectomy was associated with reduced breast cancer risk overall (odds ratio (OR) = 0.59, 95% confidence interval (CI): 0.50, 0.69) and among women <45 years of age (ORs ranged from 0.31 to 0.52), but not among those who were older at surgery. It was also associated with a reduced risk for estrogen and progesterone receptor-positive tumors (OR = 0.63, 95% CI: 0.52, 0.75) but not receptor-negative tumors. Hysterectomy with ovarian conservation (OR = 0.83, 95% CI: 0.72, 0.96) and hysterectomy with partial ovary removal (OR = 0.73, 95% CI: 0.59, 0.91) were also associated with lower risk. No association with breast cancer risk was observed with tubal sterilization only or partial ovariectomy without hysterectomy. Reproductive organ surgeries may alter ovarian hormone levels, thereby affecting breast cancer risk.

Risk factors for lymphedema after breast cancer treatment.

BACKGROUND: As cancer treatments evolve, it is important to reevaluate their effect on lymphedema risk in breast cancer survivors. METHODS: A population-based random sample of 631 women from metropolitan Philadelphia, Pennsylvania, diagnosed with incident breast cancer in 1999 to 2001, was followed for 5 years. Risk factor information was obtained by questionnaire and medical record review. Lymphedema was assessed with a validated questionnaire. Using Cox proportional hazards models, we estimated the relative incidence rates [hazard ratios (HR)] of lymphedema with standard adjusted multivariable analyses ignoring interactions, followed by models including clinically plausible treatment interactions. RESULTS: Compared with no lymph node surgery, adjusted HRs for lymphedema were increased following axillary lymph node dissection [ALND; HR, 2.61; 95% confidence interval (95% CI), 1.77-3.84] but not sentinel lymph node biopsy (SLNB; HR, 1.04; 95% CI, 0.58-1.88). Risk was not increased following irradiation [breast/chest wall only: HR, 1.18 (95% CI, 0.80-1.73); breast/chest wall plus supraclavicular field (+/- full axilla): HR, 0.86 (95% CI, 0.48-1.54)]. Eighty-one percent of chemotherapy was anthracycline based. The HR for anthracycline chemotherapy versus no chemotherapy was 1.46 (95% CI, 1.04-2.04), persisting after stratifying on stage at diagnosis or number of positive nodes. Treatment combinations involving ALND or chemotherapy resulted in approximately 4- to 5-fold increases in HRs for lymphedema [e.g., HR of 4.16 (95% CI, 1.32-12.45) for SLNB/chemotherapy/no radiation] compared with no treatment. CONCLUSION: With standard multivariable analyses, ALND and chemotherapy increased lymphedema risk whereas radiation therapy and SLNB did not. However, risk varied by combinations of exposures. IMPACT: Treatment patterns should be considered when counseling and monitoring patients for lymphedema.

Hormone therapy and fatal breast cancer.

PURPOSE: Among unanswered questions is whether menopausal use of estrogen therapy (ET) or estrogen-plus-progestin therapy (CHT) increases risk of developing fatal breast cancer i.e., developing and dying of breast cancer. Using a population-based case-control design, we estimated incidence rate ratios of fatal breast cancer in postmenopausal hormone therapy (HT) users compared to non-users by type, duration, and recency of HT use. METHODS: HT use prior to breast cancer diagnosis in 278 women who died of breast cancer within 6 years of diagnosis (cases) was compared with use in 2224 controls never diagnosed with breast cancer using conditional logistic regression. Measures taken to address potential bias and confounding inherent in case-control studies included collecting and adjusting for detailed data on demographic and other factors potentially associated both with HT use and breast cancer. RESULTS: Fifty-six per cent of cases and 68% of controls reported HT use. Among current 3+ year HT users, odds ratios and 95% confidence intervals for death were 0.83 (0.50, 1.38) and 0.69 (0.44, 1.09), respectively, for exclusive use of CHT or of ET, and were 0.94 (0.59, 1.48) and 0.70 (0.45, 1.07) for any use of CHT or of ET regardless of other hormone use. CONCLUSION: Point estimates suggest no increased risk of fatal breast cancer with HT use, although 50% increases in risk in longer-term current CHT users cannot be ruled out.

Lymphedema in breast cancer survivors: incidence, degree, time course, treatment, and symptoms.

PURPOSE: To examine the incidence, degree, time course, treatment, and symptoms of lymphedema in breast cancer survivors. METHODS: We conducted a 5-year, population-based prospective study of 631 randomly selected Philadelphia and Delaware County, Pennsylvania female residents with incident breast cancer who were diagnosed from 1999 to 2001. Using a questionnaire previously validated against physical therapists' measurement-based clinical criteria, we assigned a score indicating the degree of lymphedema (none, mild, or moderate/severe) to each month of follow-up based on the respondent's perceived differences in hand/arm size. Standard survival analysis methods permitted maximum use of follow-up. RESULTS: Five-year cumulative incidence of lymphedema was 42 (42%) per 100 women. Among the 238 affected women, lymphedema first occurred within 2 years of diagnosis in 80% and within 3 years in 89%. Among 433 women observed for 3 years, 23% reported no more than mild lymphedema, 12% reported moderate/severe lymphedema, and 2% reported chronically moderate/severe lymphedema. Women with mild lymphedema were more than three times more likely to develop moderate/severe lymphedema than women with no lymphedema. Thirty-seven percent of women with mild lymphedema and 68% with moderate/severe lymphedema received treatment. Increasing proportions of women with increasing degree of lymphedema reported symptoms (eg, jewelry too tight, tired/thick/heavy arm). Symptoms present before the first occurrence of lymphedema were associated with a higher probability of later lymphedema (eg, hazard ratio for jewelry too tight = 7.37; 95% CI, 4.26 to 12.76). CONCLUSION: Lymphedema after breast cancer is common but mostly mild. Subtle differences in self-reported hand/arm size and symptoms can be early signs of progressing lymphedema.

Timing of menarche and first full-term birth in relation to breast cancer risk.

Ages at menarche and first birth are established risk factors for breast cancer. The interval between these ages may also affect risk, since the breast is more susceptible to carcinogenic insults during this period than during the parous period. However, few investigators have studied this relation. Using logistic regression, the authors evaluated associations between the timing of reproductive events and breast cancer risk among 4,013 cases and 4,069 controls enrolled in a multicenter, population-based US case-control study of White and African-American women (1994-1998). For White, parous premenopausal and postmenopausal women, those who had an interval of > or =16 years between the ages of menarche and first birth had 1.5-fold (95% confidence interval (CI): 1.0, 2.2) and 1.4-fold (95% CI: 1.1, 1.8) increased risks of breast cancer, respectively, in comparison with those who had < or =5 years between these ages. Adjusting for age at first birth altered these risk estimates somewhat, to odds ratios of 1.5 (95% CI: 0.8, 2.9) and 1.0 (95% CI: 0.6, 1.5), respectively. These associations were stronger for lobular and hormone-receptor-positive tumors but were absent among premenopausal African-American women. The authors conclude that the interval between age at menarche and age at first birth is associated with the risk of hormonally sensitive types of breast cancer, particularly among White women.

Projecting individualized absolute invasive breast cancer risk in African American women.

BACKGROUND: The Breast Cancer Risk Assessment Tool of the National Cancer Institute (NCI) is widely used for counseling and determining eligibility for breast cancer prevention trials, although its validity for projecting risk in African American women is uncertain. We developed a model for projecting absolute risk of invasive breast cancer in African American women and compared its projections with those from the Breast Cancer Risk Assessment Tool. METHODS: Data from 1607 African American women with invasive breast cancer and 1647 African American control subjects in the Women's Contraceptive and Reproductive Experiences (CARE) Study were used to compute relative and attributable risks that were based on age at menarche, number of affected mother or sisters, and number of previous benign biopsy examinations. Absolute risks were obtained by combining this information with data on invasive breast cancer incidence in African American women from the NCI's Surveillance, Epidemiology and End Results Program and with national mortality data. Eligibility screening data from the Study of Tamoxifen and Raloxifene (STAR) trial were used to determine how the new model would affect eligibility, and independent data from the Women's Health Initiative (WHI) were used to assess how well numbers of invasive breast cancers predicted by the new model agreed with observed cancers. RESULTS: Tables and graphs for estimating relative risks and projecting absolute invasive breast cancer risk with confidence intervals were developed for African American women. Relative risks for family history and number of biopsies and attributable risks estimated from the CARE population were lower than those from the Breast Cancer Risk Assessment Tool, as was the discriminatory accuracy (i.e., concordance). Using eligibility screening data from the STAR trial, we estimated that 30.3% of African American women would have had 5-year invasive breast cancer risks of at least 1.66% by use of the CARE model, compared with only 14.5% by use of the Breast Cancer Risk Assessment Tool. The numbers of cancers predicted by the CARE model agreed well with observed numbers of cancers (i.e., it was well calibrated) in data from the WHI, except that it underestimated risk in African American women with breast biopsy examinations. CONCLUSIONS: The CARE model usually gave higher risk estimates for African American women than the Breast Cancer Risk Assessment Tool and is recommended for counseling African American women regarding their risk of breast cancer.

Protection of mammography screening against death from breast cancer in women aged 40-64 years.

OBJECTIVE: This study assessed the efficacy of community-based screening mammography in protecting against breast cancer death, asking whether age differences in efficacy persisted in the 1990s. METHODS: In a case-control study with follow-up, odds ratios (OR) were used to estimate the relative mortality rates from invasive breast cancer among women with at least one screening mammogram in the two years prior to a baseline reference date compared to non-screened women, adjusting for potential confounding. The multicenter population-based study included 553 black and white women diagnosed during 1994-1998 who died in the following five years, and 4016 controls without breast cancer. RESULTS: Efficacy for reducing the rate of breast cancer death within five years after diagnosis was greater at ages 50-64 years (OR = 0.47, 95% confidence interval (CI) 0.35-0.63) than at ages 40-49 (OR = 0.89, 95% CI 0.65-1.23), and greater among postmenopausal (OR = 0.45, 95% CI 0.33-0.62) than premenopausal women (OR = 0.74, 95% CI 0.53-1.04). Estimates of efficacy were conservative, as shown by sensitivity analyses addressing whether cancer was discovered by a screening mammogram, age at which screening was received, the length of the screening observation window, and years of follow-up after diagnosis. CONCLUSIONS: Despite the persistence of age differences in efficacy of mammography screening, with greater observed benefit for women aged 50-64 years, these findings support current screening recommendations for women 40-64 years old.

The intersection of cancer and aging: establishing the need for breast cancer rehabilitation.

The increasing success of treatments for common cancers has resulted in growing awareness of the unique health care needs of cancer survivors. Cancer treatments can be toxic and have long-lasting effects on health, potentially accelerating the aging process and producing associated declines in physical function. In this synthesis of the literature, we critically examine the strength of existing evidence that breast cancer diagnosis and treatment are associated with a disproportionate decline in physical function compared with the effects of living without cancer for the same number of years. There is some observational epidemiologic evidence that women treated for breast cancer report greater declines in physical function than their peers. Discerning the factors associated with such declines and their clinical significance remains to be addressed. Physiologic, psychological, and behavioral changes associated with both aging and cancer treatment are reviewed. Parallels are proposed between existing preventive and rehabilitative programs and possibilities for similar interventions aimed at preventing, reversing, or halting declines in physical function in cancer survivors. Finally, a program of research is proposed to evaluate whether there is some subset of breast cancer survivors for whom prevention or rehabilitation of functional status declines is needed, as well as development of targeted, mechanistically driven interventions.

Modifiable risk factors for breast cancer recurrence: what can we tell survivors?

The potential for recurrence causes considerable distress for breast cancer survivors. Major information sources for survivors and providers offer few clear recommendations for postdiagnosis lifestyle change related to recurrence. To design interventions to improve long-term survivors' care and quality of life, we must know what survivors are doing to prevent recurrence in the absence of solid evidence, whether survivors' perceptions and behaviors correspond to hypothesized modifiable risk factors for recurrence, and whether survivors are adopting behaviors that could otherwise be harmful to their health. Our review first addresses the general lack of consensus on the impact of specific lifestyle factors on breast cancer recurrence and the resulting equivocal lifestyle recommendations for survivors. Second, we describe inadequacies of the studies of survivors' lifestyle changes related to recurrence. Because much of the existing knowledge about modifiable risk factors for recurrence comes from studies of survivors whose participation and behavior change were potentially influenced by their concern about recurrence, we need large, population-based observational studies of randomly selected breast cancer survivors, adequately representing the target population. Critical are data on lifestyle change from prediagnosis to postdiagnosis and changes over time after diagnosis, extensive data on conventional and nonconventional treatments, and the temporal relationship between behaviors and treatments, and inclusion of the full complement of potential lifestyle risk factors for recurrence. Understanding in detail the current status of survivors' perceptions and behaviors related to modifiable risk factors for recurrence can provide considerable practical information to inform future interventions and communication strategies for breast cancer survivors.

Pairwise combinations of estrogen metabolism genotypes in postmenopausal breast cancer etiology.

Estrogen exposures have been associated with breast cancer risk, and genes involved in estrogen metabolism have been reported to mediate that risk. Our goal was to better understand whether combinations of candidate estrogen metabolism genotypes are associated with breast cancer etiology. A population-based case-control study in three counties of the Philadelphia Metropolitan area was undertaken. We evaluated seven main effects and 21 first-order interactions in African Americans and European Americans for genotypes at COMT, CYP1A1, CYP1A2, CYP1B1, CYP3A4, SULT1A1, and SULT1E1 in 878 breast cancer cases and 1,409 matched random digit-dialed controls. In European Americans, we observed main effect associations of genotypes containing any CYP1A1*2C (odds ratio, 1.71; 95% confidence interval, 1.09-2.67) and breast cancer. No significant main effects were observed in African Americans. Three significant first-order interactions were observed. In European Americans, interactions between SULT1A1*2 and CYP1A1*2C genotypes (P(interaction) < 0.001) and between SULT1E1 and CYP1A2*1F genotypes were observed (P(interaction) = 0.006). In African Americans, an interaction between SULT1A1*2 and CYP1B1*4 was observed (P(interaction) = 0.041). We applied the false-positive report probability approach, which suggested that these associations were noteworthy; however, we cannot rule out the possibility that chance led to these associations. Pending future confirmation of these results, our data suggest that breast cancer etiology in both European American and African American postmenopausal women may involve the interaction of a gene responsible for the generation of catecholestrogens with a gene involved in estrogen and catecholestrogen sulfation.

Risk of breast cancer associated with short-term use of oral contraceptives.

OBJECTIVE: To estimate breast cancer risk associated with short-term (<6 months) oral contraceptive use, and explore variation in estimates by use characteristics and medical, menstrual, and reproductive history. METHODS: We analyzed data from the Women's Contraceptive and Reproductive Experiences Study. Case subjects were white women and black women, 35-64 years old, diagnosed with invasive breast cancer in July 1994-April 1998. Control subjects identified by random-digit dialing were matched to case subjects by age, race, and study site. Conditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: Overall, short-term oral contraceptive use was not associated with breast cancer risk (OR = 1.0; 95% CI = 0.8-1.1). However, significant interaction between short-term use and menopausal status led to an observed increased breast cancer risk in pre-menopausal women (OR = 1.3; 95% CI = 1.0-1.7) and a reduced risk in post-menopausal women (OR = 0.8; 95% CI = 0.6-1.0) associated with short-term use. The association was more pronounced in women with non-contraceptive reasons for use and underlying risk factors for breast cancer. CONCLUSIONS: These associations may result from underlying characteristics of users or unmeasured factors influencing duration of use and breast cancer risk.

A retrospective case-control study of the use of hormone-related supplements and association with breast cancer.

Hormone-related supplements (HRS), many of which contain phytoestrogens, are widely used to manage menopausal symptoms, yet their relationship with breast cancer risk has generally not been evaluated. We evaluated whether use of HRS was associated with breast cancer risk, using a population-based case-control study in 3 counties of the Philadelphia metropolitan area consisting of 949 breast cancer cases and 1,524 controls. Use of HRS varied significantly by race, with African American women being more likely than European American women to use any herbal preparation (19.2% vs. 14.7%, p=0.003) as well as specific preparations including black cohosh (5.4% vs. 2.0%, p=0.003), ginseng (12.5% vs. 7.9%, p<0.001) and red clover (4.7% vs. 0.6%, p<0.001). Use of black cohosh had a significant breast cancer protective effect (adjusted odds ratio 0.39, 95% CI: 0.22-0.70). This association was similar among women who reported use of either black cohosh or Remifemin (an herbal preparation derived from black cohosh; adjusted odds ratio 0.47, 95% CI: 0.27-0.82). The literature reports that black cohosh may be effective in treating menopausal symptoms, and has antiestrogenic, antiproliferative and antioxidant properties. Additional confirmatory studies are required to determine whether black cohosh could be used to prevent breast cancer.

Prevalence and predictors of BRCA1 and BRCA2 mutations in a population-based study of breast cancer in white and black American women ages 35 to 64 years.

Although well studied in families at high-risk, the roles of mutations in the BRCA1 and BRCA2 genes are poorly understood in breast cancers in the general population, particularly in Black women and in age groups outside of the very young. We examined the prevalence and predictors of BRCA1 and BRCA2 mutations in 1,628 women with breast cancer and 674 women without breast cancer who participated in a multicenter population-based case-control study of Black and White women, 35 to 64 years of age. Among cases, 2.4% and 2.3% carried deleterious mutations in BRCA1 and BRCA2, respectively. BRCA1 mutations were significantly more common in White (2.9%) versus Black (1.4%) cases and in Jewish (10.2%) versus non-Jewish (2.0%) cases; BRCA2 mutations were slightly more frequent in Black (2.6%) versus White (2.1%) cases. Numerous familial and demographic factors were significantly associated with BRCA1 and, to a lesser extent, BRCA2 carrier status, when examined individually. In models considering all predictors together, early onset ages in cases and in relatives, family history of ovarian cancer, and Jewish ancestry remained strongly and significantly predictive of BRCA1 carrier status, whereas BRCA2 predictors were fewer and more modest in magnitude. Both the combinations of predictors and effect sizes varied across racial/ethnic and age groups. These results provide first-time prevalence estimates for BRCA1/BRCA2 in breast cancer cases among understudied racial and age groups and show key predictors of mutation carrier status for both White and Black women and women of a wide age spectrum with breast cancer in the general population.

Benefit of screening mammography in reducing the rate of late-stage breast cancer diagnoses (United States).

OBJECTIVE: We studied the benefit of modern mammography screening in community settings, evaluating age-related differences in rates of late-stage breast cancer detection. METHODS: Our multicenter population-based case-control study included 931 black and white women with incident breast cancer (American Joint Commission on Cancer Stage IIB or higher) diagnosed 1994-1998 and 4,016 randomly sampled controls never diagnosed with breast cancer. Adjusted odds ratios (ORs) estimated the relative rate of late-stage diagnosis in screened and non-screened women. RESULTS: Women aged 50-64 at diagnosis with at least one screening mammogram in the previous 2 years were significantly less likely to have late-stage diagnosis (OR = 0.41, 95% CI 0.33-0.52). Results for women aged 40-49 were consistent with a screening benefit, although the confidence interval marginally overlapped the null (OR = 0.81, 95% CI 0.64-1.02). Mammography screening was associated with lower rates of late-stage breast cancer among both premenopausal (OR = 0.64, 95% CI 0.50-0.81) and postmenopausal (OR = 0.44, 95% CI 0.35-0.56) women. CONCLUSIONS: With modern mammography in the community, rates of late-stage breast cancer diagnoses are lower in screened compared to non-screened women ages 40 and older, but age-related differences persist.

Measuring screening intensity in case-control studies of the efficacy of mammography.

Of great interest in studies of screening for breast cancer is the relative efficacy of different screening frequencies (intensities). Prior work has suggested that estimates of the association between screening intensity and outcome in case-control studies would not produce valid results and that only binary indicators (no screens vs. one or more) of exposure can be used. Using case-control studies drawn from simulated cohorts of 30,000-40,000 women, the authors found that biases demonstrated in prior studies can be explained by 1) misclassification of true exposure groups by observed screening history, and 2) differential exposure misclassification of cases and controls. Binary as well as ordered categorical and interval measures can be biased unless they account for misclassification. By combining measurements of screening history from multiple periods of observation of varying lengths and using repeated-measures logistic regression models, the effect of screening intensity can be estimated in the presence of misclassification. Assessing the effect of screening intensity in case-control studies of mammography is possible if principles and methods for misclassification and measurement error guide the analysis.