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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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