Girls Born to Older Mothers Have Increased Risk of Breast Cancer

Pregnancy and Offspring Risk of Breast Cancer
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There are many factors linked to breast cancer risk, some of which you cannot control. One factor that increases personal risk is simply aging. However, a new study finds that women who are older when they become pregnant also increase the risk of their daughters later developing breast cancer due to increased breast density, another established risk factor.

During the 2010 annual meeting of the American Association for Cancer Research (AACR), various studies were presented that support findings that showed that women with a mammographic density of 75% or above are five times more likely to develop breast cancer in comparison to women with a low density.

Breast density on its own is hereditary but exposures to factors in utero such as estrogen and insulin-like growth factor (IGF-1) has been observationally linked to breast cancer in offspring. This is a topic currently under investigation states Susan G. Komen for the Cure, the largest source of nonprofit funds dedicated to fighting breast cancer around the world. Virginia Lope of the Carlos III Health Institute in Spain says that “accumulated exposure to hormones along with growth factors in earlier stages of life when the breasts begin to develop…influence the probability of developing a tumor as an adult.”

In the journal Breast Cancer Research and Treatment, Lope and her team with the National Centre for Epidemiology at ISCIII evaluated a sample of over 3,500 women aged 45 to 68 years. The team found that women born to older mothers – those above 39 years – tend to have a higher breast density which increases the risk of developing cancer. They also found that women who were taller and thinner than the average girl prior to puberty may also be at risk. But those whose breast density was reduced over a period of time (six years) were less at risk than those whose density remained stable.

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Women who are over the age of 35 when they first give birth have a 40% increased risk than those who have children before age 20, says the National Cancer Institute. Because estrogen levels are lower during pregnancy, breast tissue is exposed to more estrogen in women who become pregnant for the first time later in adulthood. Additionally, age increases the risk of genetic damage to breast cells. During pregnancy, when these cells grow rapidly, more abnormal cells may be copied.

Another risk factor for breast cancer is tall stature and thinner body weight at prior to puberty. Although obesity is considered to increase breast cancer risk in postmenopausal women, in young girls the opposite is true. Being somewhat overweight as a child appears to be protective of developing breast cancer before menopause. Being tall is associated with higher levels of various growth hormones which affect breast cancer risk.

Journal Reference:
Virginia Lope; Beatriz Pérez-Gómez; et al. "Childhood factors associated with mammographic density in adult women". Breast Cancer Research and Treatment, diciembre de 2011. DOI 10.1007/s10549-011-1664-2

Additional References:
Schernhammer ES. In-utero exposures and breast cancer risk: joint effect of estrogens and insulin-like growth factor? Cancer Causes Control. 2002 Aug;13(6):505-8.
Ahlgren Martin MD, et al. Growth Patterns and the Risk of Breast Cancer in Women. N Engl J Med 2004; 351:1619-1626October 14, 2004

Photo Credit: Morguefile.com

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