Navigation Links
Multiple childbirth linked to increased risk of rare, aggressive 'triple-negative' breast cancer

SEATTLE Full-term pregnancy has long been associated with a reduced risk of breast cancer, but a new study finds that the more times a woman gives birth, the higher her risk of "triple-negative" breast cancer, a relatively uncommon but particularly aggressive subtype of the disease. Conversely, women who never give birth have a 40 percent lower risk of such breast cancer, which has a poorer prognosis than other types of breast cancer and doesn't respond to hormone-blocking therapies such as tamoxifen.

These findings, from a study led by Amanda Phipps, Ph.D., a postdoctoral research associate in the Public Health Sciences Division of Fred Hutchinson Cancer Research Center, are published online ahead of the March 16 issue of the Journal of the National Cancer Institute.

"Unlike most breast cancers, triple-negative tumors don't depend on hormonal exposures to grow and spread, so our assumption going into the study was that reproductive factors would not be associated with a woman's risk of this cancer subtype," Phipps said. "We were surprised by these findings because researchers have known for quite some time that women who have children, especially those who have them at an early age and have multiple full-term pregnancies, have a lower risk of breast cancer overall."

While never giving birth appears to be protective against triple-negative breast cancer, the researchers found that women who remain childless have about a 40 percent higher risk of estrogen-receptor-positive breast cancer the most common form of the disease, which can be treated with estrogen-blocking drugs as compared to those who have one or more offspring. This higher risk of estrogen-receptor-positive breast cancer among women who have not had children is well established, and it is thought to be related to the fact that such women do not undergo pregnancy-related changes in the breast that confer a lifelong protective effect.

"The mechanisms by which full-term pregnancy contributes to an increased risk of triple-negative breast cancer and a decreased risk of other forms of the disease are not clear," Phipps said. "We do know that the hormones of pregnancy induce certain changes in the cellular structure of the breast. Overall, those changes seem to make the breast less susceptible to cancer. It is possible, however, that the increased risk of triple-negative breast cancer we found in women who had given birth may be due to some abnormal response of their breast tissue to the hormones of pregnancy. Another possibility is that pregnancy somehow makes the breast more susceptible to certain carcinogens even while reducing breast cancer risk overall," she said.

For the study, which was based on data from the Women's Health Initiative, Phipps and colleagues analyzed the detailed reproductive histories of some 150,000 postmenopausal women, more than 300 of whom went on to develop triple-negative breast cancer. "This particular study is significant because it is one of the largest studies ever conducted on the impact of reproductive history on triple-negative breast cancer," Phipps said.

Triple-negative breast cancer, which refers to any breast cancer that does not express the genes for estrogen receptor (ER), progesterone receptor (PR) or Her2/neu, accounts for only 10 percent to 20 percent of all breast cancers, and only in the past decade have researchers become aware that this cancer subtype exists. "This research reinforces the notion that breast cancer is not just one disease," Phipps said.

"The mechanisms that lead to triple-negative breast cancer are likely different from those that lead to other forms of the disease. We still have a lot to learn about what causes this more aggressive form of breast cancer, but we hope that research like this will help us develop better tools to identify those women at greatest risk."

It is known that this cancer subtype is more predominant in African American women and it tends to be diagnosed at an earlier age. Researchers also know there is a strong link between genetic mutations in the so-called "breast cancer gene," BRCA1, and triple-negative breast cancer.

"More research is needed to better understand the causes of the most aggressive and lethal forms of breast cancer. While this study adds to our knowledge base, it should not change women's approaches to breast cancer screening," Phipps said.


Contact: Kristen Woodward
Fred Hutchinson Cancer Research Center

Related medicine news :

1. Wayne State University researchers publish results settling multiple sclerosis debate
2. VCU Massey first to combine targeted agents to kill multiple myeloma cells
3. Most ADHD Kids Have Multiple Conditions, Study Says
4. More than allergies: Histamine may be a possible drug target for multiple sclerosis
5. Tiny RNA shown to cause multiple types of leukemia
6. Laboratory studies show promise for new multiple sclerosis treatment
7. Common for patients to undergo multiple cardiac imaging tests, with high cumulative radiation dose
8. Multiple fathers prevalent in Amazonian cultures
9. Multiple sclerosis will become a controlled disease like AIDS
10. Radiation therapy improves painful condition associated with multiple sclerosis
11. TGen-Mayo Clinic study discovers role of DNA methylation in multiple myeloma blood cancer
Post Your Comments:
(Date:10/13/2015)... ... October 13, 2015 , ... ... first commercially-available next-generation sequencing laboratory test for bacterial vaginosis- a significant women's ... in Vancouver, BC, Canada. , In a presentation entitled: "The Microbiome ...
(Date:10/12/2015)... ... October 13, 2015 , ... Career Step, ... the release of its new Professional Medical Coding and Billing with Applied PCS ... ICD-10-CM and ICD-10-PCS code sets, earn the Certified Professional Coder (CPC) and Certified ...
(Date:10/12/2015)... ... 12, 2015 , ... According to an article from ... particularly in the area of track and field, are at a significantly higher ... peers in the same age group. Dr. Steven Meier of Meier Orthopedic Sports ...
(Date:10/12/2015)... ... 12, 2015 , ... According to an article published by Texas ... Texas recommended that any high-rises in the city limits that do not have fire ... article explains that it wasn’t until 1982 that the city started requiring fire sprinklers ...
(Date:10/12/2015)... ... October 12, 2015 , ... AcousticSheep LLC, creators of the ... honor of Breast Cancer Awareness Month. During the month of October, for ... SleepPhones® Classic product to a breast cancer patient at the Cleveland Clinic. , ...
Breaking Medicine News(10 mins):
(Date:10/12/2015)... -- Use this report to: - Learn ... the medical membrane devices market. - Analyze the present ... medical membrane devices market including hemodialyzers, membrane oxygenators, intravenous ... devices. - Gain information on newly approved products, recalls ... Use this report to: - Learn about the performance, ...
(Date:10/12/2015)... and CRANBURY, N.J. , Oct. ... LLP announces that a securities fraud class ... for the District of New Jersey.  The complaint alleges ... FOLD) violated the Securities Exchange Act of 1934 between ... materially false and misleading statements about Amicus Therapeutics, business ...
(Date:10/12/2015)... , Oct. 12, 2015  MiMedx Group, Inc. ... utilizing human amniotic tissue and patent-protected processes to develop ... Care, Surgical, Orthopedic, Spine, Sports Medicine, Ophthalmic, and the ... results for the third quarter of 2015, its guidance ... Company has secured a $50 million Senior Secured Credit ...
Breaking Medicine Technology: