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New finding sheds light on triple negative breast cancer risk

Kathleen Blanchard's picture

Women who have children at a younger age might have a higher risk of aggressive breast cancer. Fred Hutchinson Cancer researchers say the finding is especially important for African-American women who suffer from higher rates of triple negative breast cancer compared to non-Hispanic white women and who are also less likely to breast feed.

The researchers found women who wait at least 15 years after onset of menstruation had a 60 percent lower chance of developing aggressive breast cancer that though uncommon has the worst outcomes.

Aggressive triple-negative breast cancer is especially challenging because it doesn’t rely on estrogen to grow and doesn’t respond to treatment with Tamoxifen that blocks the hormone estrogen.

Christopher I. Li, M.D., Ph.D., a member of the Public Health Sciences Division at Fred Hutchinson said in a press release, “This type of cancer, which accounts for only 10 percent to 20 percent of all breast cancers, does not express the genes for estrogen receptor (ER), progesterone receptor (PR) or HER2/neu and therefore does not respond to hormone-blocking drugs such as Tamoxifen.

The finding is the first to look at timing of childbirth related to triple-negative breast cancer. The researchers were also able to confirm that breast-feeding is a strong protector against the disease, though the reasons aren’t clear.

Researchers suspect that pregnancy and breast feeding changes the structure of breast cells making them susceptible to changes that can lead to cancer.

“Our observations that delayed childbearing and breast-feeding are protective against triple-negative breast cancer suggest that variations in reproductive histories by race may to some extent explain the higher rates of triple-negative disease in African-American women,” Li said.

The researchers warn that the study is observational should be confirmed. The finding comes from data collected from 1,960 Seattle-area women between the ages of 20 and 44. Among the women 941 did not have a history of breast cancer and 1021 had the disease.

The investigation included reproductive history of the women and comparison of those without the disease and women diagnosed with ER-positive (781), triple-negative (180) and HER2-overexpressing (60) breast cancer.

Lifestyle and genes

The new finding adds to a growing body of evidence that lifestyle factors can thwart disease.

Women who are at higher risk for aggressive forms of the disease that is a subtype of breast cancer are more likely to have recurrence. Compared to other types of breast cancer, survival rates are lower, leading to more focus on prevention and treatment.

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Lifestyle factors are important for lowering your chances of breast cancer. Genes also play a role in development of the disease.

If a family member has had triple negative breast cancer you may be a higher risk. Your doctor might recommend genetic testing. Having the breast cancer genes increases your chance of being diagnosed by the disease 80 percent.

Women who carry genes that put them at risk for aggressive disease should be screened younger than age 40. It’s also important to perform regular breast exams.

MRI or digital mammogram should be performed twice a year for women with the BRCA1 or BRCA2 gene, beginning at age 30; recommended by the Memorial Sloan-Kettering Cancer Center in New York, NY.

Some women opt for bilateral mastectomy to reduce their chances of the disease that lowers the risk, but can still develop in areas where the breast used to be.

Lifestyle factors that are known to reduce chances of the disease include eating plenty of fruits and vegetables, maintaining a normal weight and ensuring you don’t gain weight in the mid-section, limiting your alcohol intake and avoiding tobacco smoke.

Recommendations for a healthy diet that can help thwart cancer include eating at least 5 cups of fruits and vegetables each day that can boost immunity. It’s also important to choose a variety of colors when choosing your fruits and veggies to ensure you’re getting a wide wide array of antioxidants.

It’s also important to limit processed meats and cold cuts and high fat foods like butter, margarines and salad dressings. If you do eat meat, make sure it’s lean. Recommendations are for no more than 3 ounces of meat twice a day.

Fiber from cereals, beans, whole grains and fruits and vegetables can also stave off hunger so you don’t overeat. Consider buying organic foods to reduce exposure to pesticides.

Understanding how to prevent breast cancer has been a focus of researchers. The new finding adds to a list of ways women can take charge of their health. Delaying childbirth and breast feeding could be important ways to lower risk of especially aggressive triple negative breast cancer, pending confirmation of the observational findings.

Fred Hutchinson Cancer Center
December 12, 2012


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I was a twin. Unfortunately, my twin was diagnosed with Inflammatory Breast Cancer at the age of 33, was triple negative which meant it was harder for chemo to work for her. She went into remission but had a recurrence almost 3 years later and passed away at the age of 38. Yvonne did wait to have a child after 15 years from when she first had menstrual period, never breast fed and still was triple negative. Since Yvonne diagnosis, I get checked constantly and hopefully will never develop cancer. I wished my sister would have never developed the most aggressive breast cancer "Inflammatory Breast Cancer" nor would have been triple negative because then she would still be here with me.
Cynthia, you have my heartfelt condolences and sympathy for your loss. Thank you for sharing your sister's experience. We will all keep pushing for and praying for a cancer cure - all types of cancer.
Hi Cynthia, I, too sympathize with you. One of the causes of breast cancer, according to many scientist, is cows milk. It probably is not the only cause, but a good place to start while you do further research. If you type in your web browser; 'Breast cancer and dairy', or 'Is dairy causing breast cancer', or 'diseases caused by dairy consumption'. You will find heaps of info to vindicate dairy as a causal factor in the etiology of cancer. "IGF-I is critically involved in the aberrant growth of human breast cancer cells." M. Lippman. J. Natl. Inst. Health Res., 1991, 3. "Estrogen regulation of IGF-I in breast cancer cells would support the hypothesis that IGF-I has a regulatory function in breast cancer." A.V. Lee, Mol-Cell- Endocrinol., March, 99(2). "IGF-I is a potent growth factor for cellular proliferation in the human breast carcinoma cell line." J.C. Chen, J-Cell-Physiol., January, 1994, 158(1) "Insulin-like growth factors are key factors for breast cancer growth." J.A. Figueroa, J-Cell-Physiol., Nov., 1993, 157(2) "IGF-I produces a 10-fold increase in RNA levels of cancer cells. IGF-I appears to be a critical component in cellular proliferation." X.S. Li, Exp-Cell-Res., March, 1994, 211(1) "IGF-I plays a major role in human breast cancer cell growth." E.A. Musgrove, Eur-J-Cancer, 29A (16), 1993 "IGF-I has been identified as a key factor in breast cancer." Hankinson. The Lancet, vol. 351. May 9, 1998 "Serum IGF-I levels increased significantly in milk drinkers, an increase of about 10% above baseline but was unchanged in the control group." Robert P. Heaney, Journal of the American Dietetic Association, vol. 99, no. 10. October 1999 "IGF-1 accelerates the growth of breast cancer cells." M. Lippman Science, Vol. 259, January 29, 1993
No proven link -please be careful - the studies were pooled and analyzed - those are suggestions. Please be clear.