Mothers who give birth to large infants at increased risk for breast cancer

July 17, 2012, University of Texas Medical Branch at Galveston

Delivering a high-birth-weight infant more than doubles a woman's breast cancer risk, according to research from the University of Texas Medical Branch at Galveston. The researchers suggest that having a large infant is associated with a hormonal environment during pregnancy that favors future breast cancer development and progression.

Marking the first time that high was shown to be an independent risk factor, the finding may help improve prediction and prevention of decades before its onset.

"We also found that delivering large babies – those in the top quintile of this study, which included whose weight was 8.25 or more pounds – have increased levels of hormones that create a 'pro-carcinogenic environment.' This means that they have high levels of estrogen, low levels of anti-estrogen and the presence of free insulin-like growth factors associated with breast and progression," said lead author Dr. Radek Bukowski, professor of obstetrics and gynecology in the Division of Maternal-Fetal Medicine. "Women can't alter their hormones, but can take steps to increase their general protection against breast cancer." Dr. Bukowski notes that breastfeeding, having more than one child, following a healthy diet and exercising have been shown to reduce breast cancer risk.

The study, published in the July 17 issue of PLoS ONE, builds on accumulating evidence that a woman's own birth weight and that of her children are linked to breast cancer. However, this is the first study to explore whether each is an . Dr. Bukowski's team examined two cohorts of women from distinct data sets:

  • The Framingham Offspring Birth History Study, which has studied generations of women via medical examinations and laboratory assessments. Dr. Bukowski's team studied 410 women from this study, observed between 1991-2008, and maternal birth weight, infant birth weight and results of later examinations (e.g., breast cancer diagnosis) to determine breast cancer risk. The researchers also looked at data from the study on known breast cancer risk factors, such as age, race/ethnicity, body mass index, diabetes, use of hormone replacement therapy and maternal history of the disease, among others.
  • The First and Second Trimester Evaluation of Risk for Aneuploidy (FASTER) trial, which examined pregnancy hormones in nearly 24,000 women at 15 U.S. clinical centers between 1999 and 2003. The study included assessments of the hormones that affect infant birth weight and breast cancer risk – estriol (E3), anti-estrogen alpha-fetoprotein (AFP) and pregnancy-associated plasma protein-A (PAPP-A).
Approximately 7.6 percent of the women from the Framingham cohort in this study were later diagnosed with breast cancer. The researchers found that the risk of breast cancer was two-and-a-half times higher in women whose infant's birth weight was in the top quintile compared with women whose infant weighed in the lower quintiles. Importantly, the risk was shown to be signficiant independent of the birth weight of the mother and traditional breast factors.

Of the nearly 24,000 pregnancies studied in the FASTER trial, a strong positive relationship was observed between infant birth weight and E3, AFP and PAPP-A concentrations. For women whose infant's birth weight was in the highest quintile, there was a 25 percent increased risk of having a high E3/AFP ratio and PAPP-A concentration.

"Recent animal studies have suggested that breast stem cells, which are involved in the origins of breast cancer, may increase or decrease their number in response to hormone exposures, including ones during pregnancy," added Dr. Bukowski. "They retain a 'memory' of prior hormone exposure, which could explain the increased risk of breast cancer seen following pregnancy, especially in women with a large birth weight infant. The hormones create a long term effect that may lead to breast cancer later."

One limitation of this study is that the associations between large infants' birth weight and and between infants' birth weight and hormonal environment during pregnancy were tested in different populations of women. Further research is needed to definitively demonstrate that the concentrations of pregnancy hormones mediates the relationship between large infant birth weight and breast cancer.

Subsequent studies will also focus on testing whether having an infant of high birth weight improves prediction of future breast cancer.

Explore further: Childbearing may increase risk of hormone receptor-negative breast cancer in African-American women

Related Stories

Childbearing may increase risk of hormone receptor-negative breast cancer in African-American women

August 16, 2011
African-American women are at higher risk for hormone receptor-negative breast cancer, one of the most difficult subtypes to treat, but this risk could be ameliorated somewhat by breast-feeding their children.

Elevated hormone levels add up to increased breast cancer risk

October 21, 2011
Post-menopausal women with high levels of hormones such as estrogen or testosterone are known to have a higher risk of breast cancer. New research published in BioMed Central's open access journal Breast Cancer Research looked ...

Breast cancer type linked to paternal cancer

November 28, 2011
The risk of breast cancer is increased by genetic and lifestyle factors such as the inherited BRCA2 gene, age of having first child, or use of hormone replacement therapy (HRT). New research published in BioMed Central's ...

Exercise, even mild physical activity, may reduce breast cancer risk

June 25, 2012
A new analysis done by University of North Carolina at Chapel Hill researchers has found that physical activity – either mild or intense and before or after menopause – may reduce breast cancer risk, but substantial ...

Obesity raises breast cancer survivors' risk of dying of the cancer

June 4, 2011
Women with a healthy body weight before and after diagnosis of breast cancer are more likely to survive the disease long term, a new study finds.

Recommended for you

Researchers discover novel mechanism linking changes in mitochondria to cancer cell death

February 20, 2018
To stop the spread of cancer, cancer cells must die. Unfortunately, many types of cancer cells seem to use innate mechanisms that block cancer cell death, therefore allowing the cancer to metastasize. While seeking to further ...

Stem cell vaccine immunizes lab mice against multiple cancers

February 15, 2018
Stanford University researchers report that injecting mice with inactivated induced pluripotent stem cells (iPSCs) launched a strong immune response against breast, lung, and skin cancers. The vaccine also prevented relapses ...

Induced pluripotent stem cells could serve as cancer vaccine, researchers say

February 15, 2018
Induced pluripotent stem cells, or iPS cells, are a keystone of regenerative medicine. Outside the body, they can be coaxed to become many different types of cells and tissues that can help repair damage due to trauma or ...

Team paves the way to the use of immunotherapy to treat aggressive colon tumors

February 15, 2018
In a short space of time, immunotherapy against cancer cells has become a powerful approach to treat cancers such as melanoma and lung cancer. However, to date, most colon tumours appeared to be unresponsive to this kind ...

Can our genes help predict how women respond to ovarian cancer treatment?

February 15, 2018
Research has identified gene variants that play a significant role in how women with ovarian cancer process chemotherapy.

First comparison of common breast cancer tests finds varied accuracy of predictions

February 15, 2018
Commercially-available prognostic breast cancer tests show significant variation in their abilities to predict disease recurrence, according to a study led by Queen Mary University of London of nearly 800 postmenopausal women.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.