City of Hope Researchers Find Regular Use of Aspirin Can Lower Risk of Breast Cancer for Women

A new study, using data from the California Teachers Study,
identifies low-dose aspirin as a potential cancer prevention tool

DUARTE, Calif.–(BUSINESS WIRE)–A City of Hope-led study found that the use of low-dose aspirin (81mg)
reduces the risk of breast cancer in women who are part of the California’s
Teacher’s Study
. This study — which is the first to suggest that the
reduction in risk occurs for low-dose aspirin — was proposed by City of
Hope’s Leslie Bernstein, Ph.D., professor and director of the Division
of Biomarkers of Early Detection and Prevention, and published
in the journal, Breast Cancer Research.

Bernstein and her colleagues saw an overall 16 percent lower risk of
breast cancer in women who reported using low-dose aspirin at least
three times per week. Such regular use of low-dose aspirin reduced the
risk by 20 percent of estrogen or progesterone receptor positive, HER2
negative breast cancer, which is the most common breast cancer subtype.

“The study found an interesting protective association between low-dose
aspirin and breast cancer,” said lead author Christina A. Clarke, Ph.D.,
M.P.H., from the Cancer Prevention Institute of California. “We did not
by and large find associations with the other pain medications like
ibuprofen and acetaminophen. We also did not find associations with
regular aspirin since this type of medication is taken sporadically for
headaches or other pain, and not daily for prevention of cardiovascular

This study differed from other studies that have looked at aspirin and
cancer risk because it focused on the dose levels of the aspirin women
had taken and tracked the frequency of the use of low-dose aspirin as
opposed to regular aspirin. It was also able to look in detail at
subtypes of breast cancer.

“We already knew that aspirin is a weak aromatase inhibitor and we treat
women with breast cancer with stronger aromatase inhibitors since they
reduce the amount of estrogen postmenopausal women have circulating in
their blood,” said Bernstein. “We thought that if aspirin can inhibit
aromatase, it ought to reduce the likelihood that breast cancer would
develop and it could also be an effective way to improve breast cancer
patients’ prognosis once they no longer take the more potent aromatase
inhibitors.” Bernstein added, “Aspirin also reduces inflammation, which
may be another mechanism by which aspirin taken regularly can lower risk
of breast cancer developing or recurring.”

As part of the study, researchers analyzed data recorded in
questionnaires submitted by 57,164 women in the California’s Teacher’s
Study. In 2005, participants answered questions regarding family history
of cancer and other conditions, use of aspirin and other nonsteroidal
anti-inflammatory drugs (NSAIDS), menstrual and reproductive history,
use of hormones, weight and height, living environment, diet, alcohol
use and physical activity. In the ensuing years before 2013, 1,457 of
these participants developed invasive breast cancer.

The team of researchers chose to focus on low-dose “baby” aspirin,
because not only is it inexpensive and readily available as potential
means of prevention, but because there are already a lot of people
already taking it for prevention of other diseases such as heart disease
and even colon cancer.

“Now that we have some data separating low-dose from higher-dose
aspirin, more detailed research can be undertaken to understand the full
value of low-dose aspirin for breast cancer prevention,” said Clarke.

Other collaborating authors include Alison J. Canchola, M.S., and Lisa
M. Moy, M.P.H., from the Cancer Prevention Institute of California, and
Susan L. Neuhausen, Ph.D., The Morris & Horowitz Families Professor in
Cancer Etiology & Outcomes Research, Nadia T. Chung, M.P.H., and James
V. Lacey Jr., Ph.D., M.P.H., from City of Hope.

Research reported in Breast Cancer Research was supported through
grants from the National Cancer Institute and the California Breast
Cancer Research Fund under grant numbers: R01 CA77398 and 97-10500. The
content is solely the responsibility of the authors and does not
necessarily represent the official views of the National Institutes of

About City of Hope

City of Hope is an independent research and treatment center for cancer,
diabetes and other life-threatening diseases. Designated as one of only
47 comprehensive cancer centers, the highest recognition bestowed by the
National Cancer Institute, City of Hope is also a founding member of the
National Comprehensive Cancer Network, with research and treatment
protocols that advance care throughout the world. City of Hope is
located in Duarte, California, just northeast of Los Angeles, with
community clinics
throughout Southern California. It is ranked
as one of “America’s Best Hospitals” in cancer by U.S. News & World
Report. Founded in 1913, City of Hope is a pioneer in the fields of bone marrow transplantation,
and numerous
breakthrough cancer drugs
based on technology developed at the

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City of Hope
Denise Heady