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home > research > other Bay Area breast cancer research studies

Breast Cancer Research

*Indicates studies that used data from Zero Breast Cancer’s Adolescent Risk Factors Study.

Migration History, Acculturation, and Breast Cancer Risk in Hispanic Women

Authors
Esther M. John; Amanda I. Phipps; Adam Davis; Jocelyn Koo

Abstract
Breast cancer incidence rates vary >10-fold worldwide and have increased in most countries in the past few decades (1, 2). Differences in the prevalence of hormonal and lifestyle factors are likely to explain some of the international variation in incidence. Migrant studies have shown that, over successive generations, incidence rates increase in women who migrate from low-incidence countries in Asia and Latin America to high-incidence countries, such as the United States, Australia, or other Western countries, approaching the incidence rates observed in the host country (3-5). These changing patterns of breast cancer incidence are well shown by the experience of Japanese American women living in Los Angeles and Hawaii who now have the same incidence rates as non-Hispanic White women (6, 7). There is also some evidence to suggest that breast cancer risk among first-generation migrants is higher among those who migrated at a young age (8, 9). Together, these observations suggest that changes in hormonal or lifestyle factors following migration, possibly at a young age, influence breast cancer risk.

Hispanic women constitute a large and rapidly growing migrant population in the United States, accounting for 12.5% of the U.S. population, with a major concentration in California (10). Originating mostly from Mexico and Central American countries, Hispanic women residing in California experience the lowest breast cancer incidence rate (84 per 100,000) compared with Asian Americans (92 per 100,000), African Americans (121 per 100,000), and non-Hispanic Whites (147 per 100,000; ref. 11). As noted for Asian immigrant populations (12), U.S.-born Hispanics have a higher incidence of breast cancer than foreign-born Hispanics (7, 13, 14), but few epidemiologic studies have examined breast cancer risk factors in this population (15, 16). We conducted a large population based case-control study of breast cancer in >2,500 Hispanic women residing in the San Francisco Bay Area and report on the influence of migration patterns and acculturation on breast cancer risk. This is the largest population-based case-control of breast cancer conducted to date in Hispanic women residing in the United States.

> Download the study (pdf - 104kb)

 

*Risk Factors for Estrogen ReceptoröPositive Breast Cancer

Authors
E. Shelley Hwang, MD; Terri Chew, MS; Stephen Shiboski, PhD;
Georgianna Farren, MD; Christopher C. Benz, MD; Margaret Wrensch, PhD

Abstract
The comparatively high incidence of breast cancer in Marin County, a small, affluent county of almost 250,000 inhabitants directly north of San Francisco, has been recognized since the early 1990s. In 1997, in response to growing concern, a community organization-the Marin Breast Cancer Watch joined with researchers from the University of California, San Francisco, and the Division of Research at Kaiser to initiate a large, population-based, case-control study seeking to better understand the breast cancer risk factors that could be unique to Marin County. Their study found that many of the wellestablished factors, such as family history, age at menarche, and parity, were not different in cases and controls, possibly because of overmatching in this relatively homogeneous population. However, significant differences in alcohol consumption, socioeconomic status during adolescence, and frequency of mammographic screening were identified. This study did not find a difference in exogenous hormone use between cases and controls, and neither did the increased incidence of breast cancer in Marin County seem to be attributable to length of Marin County residence.

Recently, based on data from the Northern California Cancer Registry, it has been shown that the excess breast cancer risk in Marin County seems to be due almost entirely to an increased incidence of estrogen receptor (ER)-positive breast cancers. Furthermore, there has been growing evidence from large, prospective, randomized trials linking breast cancer to hormone therapy, substantiating the association that had been suggested by observational studies. Given that up to 70% of women 50 years and older in Marin County report a history of hormone therapy, one biologically plausible explanation for the increased incidence of breast cancer in Marin County could be the effect of exogenous hormone use, particularly on ER-positive tumors. Therefore, this study was undertaken to determine whether there exist specific risk factors for ER-positive vs ER-negative breast cancer, particularly with respect to hormone therapy.

> Download the study (pdf - 104kb)

 

Update on breast cancer incidence patterns in Marin County and the San Francisco Bay Area, California

Northern California Cancer Center, Union City, California

Authors
Christina Clarke, Ph.D; Theresa Keegan, Ph.D; Gem Le, MHS; Sally Glaser, Ph.D; Dee West, Ph.D

Abstract
Previous reports have suggested elevated rates of breast cancer in Marin County, spurring community and scientific interest. This report provides updated data regarding breast cancer patterns among white, non-Hispanic women in Marin County, other parts of the San Francisco Bay Area (SFBA) and California, using the most recent information available from the California Cancer Registry, the California Office of Vital Statistics, and the California Department of Finance (DOF). This information updates prior reports by incorporating newly released DOF population data in all calculations and presenting rates for the years 2000 and 2001.

> Download the study (pdf - 124kb)

 

Breast cancer incidence and mortality trends in an affluent population: Marin County, California, USA, 1990-1999.

Authors
Christina A Clarke, Sally L Glaser, Dee W West, Rochelle R Ereman, Christine A Erdmann, Janice M Barlow and Margaret R Wrensch

Abstract
Elevated rates of breast cancer in affluent Marin County, California, were first reported in the early 1990s. These rates have since been related to higher regional prevalence of known breast cancer risk factors, including low parity, education, and income. Close surveillance of Marin County breast cancer trends has nevertheless continued, in part because distinctive breast cancer patterns in well-defined populations may inform understanding of breast cancer etiology.

> Download the study (pdf - 197kb)

 

Breast cancer in Marin County

Author
Alice S. Whittemore

Abstract
Two articles previously published in Breast Cancer Research illustrate the high rates of breast cancer in Marin County, a wealthy, urban county immediately northwest of the city of San Francisco. I herein comment on these articles, and on the political/psychological/scientific dilemma presented by regions with high cancer rates, such as Marin County. I discuss possible causes of such cancer “clusters,” and conclude with some thoughts about the future.

> Download the study (pdf - 40kb)

 

3,3âDiindolymethane (DIM) Supplements on Urinary Hormone Metabolites (including cortisol) in Postmenopausal Women with a History of Early-Stage Breast Cancer

Authors
Kathie M. Dalessandri, Gary L. Firestone, Mark D. Fitch, H. Leon Bradlow, and Leonard F. Bjeldanes

Abstract
Dietary indoles, present in Brassica plants such as cabbage, broccoli, and Brussels sprouts, have been shown to provide potential protection against hormone-dependent cancers. 3,32-Diindolylmethane(DIM)is under study as one of the main protective indole metabolites. Postmenopausal women aged 50-70 yr from Marin County, California, with a history of early-stage breast cancer,were screenedfor interestandeligibility in this pilot study on the effect of absorbable DIM (BioResponse-DIM®) supplements on urinary hormone metabolites. The treatment group received daily DIM (108 mg DIM/day) supplements for 30 days, and the control group receivedaplacebo capsule daily for30days.Urinarymetabolite analysis included 2-hydroxyestrone (2-OHE1), 16-_ hydroxyestrone (16_-OHE1), DIM, estrone (E1), estradiol (E2), estriol (E3), 6_-hydroxycortisol (6 ß-OHC), and cortisol in the first morning urine sample before intervention and 31 days after intervention. Nineteen women completed the study, for a total of 10 in the treatment group and 9 in the placebo group. DIM-treated subjects, relative to placebo, showed a significant increase in levels of2-OHE1 (P=0.020),DIM(P= 0.045), and cortisol (P=0.039), and a nonsignificant increase of 47% in the 2-OHE1/16 a-OHE1 ratio from 1.46 to 2.14 (P= 0.059). In this pilot study, DIM increased the 2-hydroxylation of estrogen urinary metabolites.

> Download the study (pdf - 77kb)

 

Evaluating local differences in breast cancer incidence rates: A census-based methodology (United States).

Authors
Angela Witt Prehn and Dee W. West

Objectives
We used readily accessible, existing data to assess whether or not geographic variation in breast cancer incidence rates in the San Francisco Bay Area was related to the unequal distribution of known breast cancer risk factors.

Methods
Cancer registry and 1990 census block-group data were used to look at the associations between breast cancer incidence and known risk factors (including parity, urban/rural status, and socioeconomic indicators) in 25 California counties. Average annual age-adjusted invasive breast cancer incidence rates were calculated for the period 1988-1992, and adjusted morbidity ratios were computed.

Results
While breast cancer incidence in Marin County was 9 percent higher than that of the other 24 counties combined (relative risk = 1.09, 95 percent confidence interval = 1.01-1.18), this increase appeared to be due to the unequal distribution of known risk factors. Block-groups that had a high level of any risk factor had higher incidence rates, regardless of geographic location. After multivariate adjustment, breast cancer incidence no longer differed between Marin and the other counties (adjusted morbidity ratio = 1.02).

Conclusions
The results suggest that the unequal distribution of known risk factors was responsible for Marin Countyâs high breast cancer incidence rate.

> Cancer Causes and Control 1998;9:511-517 (url)

 

*Geographic Excess of Estrogen Receptor-Positive Breast Cancer

Authors
Christopher C. Benz, Christina A Clarke, and Dan H. Moore II

Abstract
Elevated and more rapidly increasing breast cancer incidence rates have been described for Marin County, California (CA), a homogeneous, high socioeconomic status population for which yearly surveillance is facilitated by its status as a county. The present study evaluates the histology and hormonal phenotype of the excess breast cancer cases occurring in white, non-Hispanic women living in Marin County between 1992 and 2000 and compares them with patterns occurring in the rest of the San Francisco Bay Area (SFBA) and other urban parts of CA. Incidence data for invasive breast cancer histological subtypes and estrogen receptor (ER) and progesterone receptor (PR) status were obtained from the 1992-2000 Surveillance, Epidemiology, and End Results program. Expected numbers for Marin County were computed based on age-specific rates for five other SFBA counties. Incidence rates were age-adjusted to the 2000 United States standard. Marin County breast cancer diagnoses during 1992-2000 compared with other SFBA and other urban CA Surveillance, Epidemiology, and End Results county rates for white, non-Hispanic women consisted of a disproportionate increase in ER+/PR+ tumors. The observed absolute excess (versus expected) numbers of Marin County ER+/PR+ lobular and nonlobular (predominantly ductal) cases were similar; however, the relative increase appeared greatest for lobular breast cancer. The progressive increase in breast cancer incidence rates observed in Marin County over the past decade is occurring in women with high prevalence of risk factors predisposing toward excess development of ER+/PR+ breast cancer.

> Cancer Epidemiology, Biomarkers & Prevention 2003 Dec;12(12):1523-7 (url)

 

Increase in Breast Cancer Incidence in Middle-aged Women during the 1990s

Authors
Angela Witt Prehn, PhD; Christina Clarke, PhD; Barbara Topol, MS; Sally Glaser, PhD; and Dee West, PhD

Objectives
The San Francisco Bay Area has a history of high breast cancer incidence rates relative to the rest of the United States. For Marin County, where Bay Area rates are highest and, moreover, have continued to increase over time, age- and tumor-specific incidence trends were compared with the rest of the region.

Methods
The study included all white women diagnosed with invasive breast cancer in 1988 to 1997 in the five-county Bay Area (N = 19807). Annual age-specific incidence rates and estimated annual percent changes (EAPCs) were calculated for women ages less than 45, 45 to 64, and greater than or equal to age 65.

Results
Women aged 45 to 64 from Marin County experienced a marked increase in breast cancer rates between 1991 and 1997 (EAPC = 8%, p = 0.02), regardless of disease stage or tumor histology. For the youngest and oldest women, no rate differences were observed by region or over time.

Conclusions
This regional difference in trend by age did not appear to be due to screening mammography or environmental exposures. Cohort exposures to breast cancer risk factors, such as oral contraceptive and/or hormone replacement therapy use, may have contributed to these rate increases. Although the reasons remain unclear, the finding may signal a rising risk of breast cancer in this demographic group.

> AEP 2002 Oct;12(7):476-81 (url)

 

*Risk factors for breast cancer in a population with high incidence rates (Adolescent Risk Factor Study)

Authors
Margaret Wrensch, Terri Chew, Georgianna Farren, Janice Barlow, Flavia Belli, Christina Clarke, Christine A. Erdmann, Marion Lee, Michelle Moghadassi, Roni Peskin-Mentzer, Charles P. Quesenberry Jr., Virginia Souders-Mason, Linda Spence, Marisa Suzuki and Mary Gould

Objectives
This report examines generally recognized breast cancer risk factors and years of residence in Marin County, California, an area with high breast cancer incidence and mortality rates.

Methods
Eligible women who were residents of Marin County diagnosed with breast cancer in 1997-99 and women without breast cancer obtained through random digit dialing, frequency-matched by cases’ age at diagnosis and ethnicity, participated in either full in-person or abbreviated telephone interviews.

Results
In multivariate analyses, 285 cases were statistically significantly more likely than 286 controls to report being premenopausal, never to have used birth control pills, a lower highest lifetime body mass index, four or more mammograms in 1990-94, beginning drinking after the age of 21, on average drinking two or more drinks per day, the highest quartile of pack-years of cigarette smoking and having been raised in an organized religion. Cases and controls did not significantly differ with regard to having a first-degree relative with breast cancer, a history of benign breast biopsy, previous radiation treatment, age at menarche, parity, use of hormone replacement therapy, age of first living in Marin County, or total years lived in Marin County. Results for several factors differed for women aged under 50 years or 50 years and over.

Conclusions
Despite similar distributions of several known breast cancer risk factors, case-control differences in alcohol consumption suggest that risk in this high-risk population might be modifiable. Intensive study of this or other areas of similarly high incidence might reveal other important risk factors proximate to diagnosis.

> Download the study (pdf - 106kb)

 

 

Studies Coming Soon

*Breast Cancer and Psychosocial Factors: Early Stressful Life Events, Social Support and Well Being

Author
Karni Ginzburg, PhD, Margaret Wrensch, PhD, Terri Chew, PhD, Georgianna Farren, MD, David Spiegel, MD

About Dr. Spiegel
Dr. David Spiegel, MD is the Medical Director of the Center for Integrative Medicine at Stanford Medical Center. Since beginning research on the effects of support groups for women with metastatic breast cancer in 1976, Dr. Spiegel has published numerous studies showing that group psychotherapeutic interventions have positive effects on mood disturbance, coping and pain. He is the author of the landmark study, Effect of Psychosocial Treatment on Survival of Patients With Metastatic Breast Cancer, and a book "Living Beyond Limits." His work was the subject of a segment on Bill Moyerâs Emmy Award-winning special "Healing and the Mind." Dr. Spiegel recently completed a study entitled Breast Cancer and Psychosocial Factors: Early Stressful Life Events, Social Support and Well Being. The sample for this study was the 600 women from Marin County who participated in the Adolescent Risk Factor Study and the Development of Breast Cancer in Marin.

This study has not yet been published.

 

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