Does this increase your risk for breast cancer?

It’s long been thought giving birth before 35 is a ‘protective’ factor when it comes to breast cancer. But a new study is challenging parts of that long-held belief.

The research, led by doctors from the University of North Carolina Gilllings School of Global Public Health, along with co-authors from the Institute of Cancer research in London, looked at data pooled from 15 prospective cohort studies including 890,000 women and over 18,000 breast cancers, all in women under the age of 55.

They found that women who had given birth actually had an increased risk for breast cancer compared to their counterparts who had never given birth to a child. Breast cancer risk was highest for the five-year period after childbirth with that risk decreasing over time until it was equal to their nulliparous counterparts (those who never had children), 24 years after the latest childbirth. Risk was greater for those women who experienced childbirths later in life. These findings were attributed to the “hormone surge” that women experience during pregnancy.

Another interesting finding – breastfeeding did not appear to impact breast cancer risk. Prior research had shown that breastfeeding was associated with an estimated 12 to 25 percent lower risk of breast cancer overall, particularly with hormone negative breast cancer which is more common at young ages. This research however found breastfeeding had no protective effect.

Experts say the research is groundbreaking.

“This study is of critical importance in terms of screening guidelines,” says Dr. Nila Alsheik, Chair of Breast Imaging at Advocate Health Care. “Currently, we look at a variety of factors when determining a woman’s risk for breast cancer. Those factors include family history of breast cancer, breast density, weight, whether a woman has given birth, to name just a few. This study gives us much more insight into one of those key factors.”

The researchers of the cohort study also found that breast cancer risk was highest for women who were older at the time of childbirth, had a family history of breast cancer or had a larger number of births.

“These findings are important because with women who are 35 years of age and over, we, as clinicians, use the term ‘Advanced Maternal Age’ (AMA),” says Dr. Alsheik. “If breast cancer risk is highest for these women just five years after giving birth that means risk could be highest at 40 years old. This number is important because some screening guidelines do not recommend women get screened until 45 or even 50. This study raises the question of whether these guidelines need to be modified in light of this new data.”

The American Cancer Society (ACS) screening guidelines for breast cancer recommend women ages 40 to 44 have the choice to start doing annual screenings with mammograms during this timeframe. They definitively state that women ages 45 to 54 should get a mammogram annually.

Advocate Health Care strongly encourages women to start getting an annual (preferably 3D) mammogram at age 40 and supports shared decision making of patients with their providers, as the American Cancer Society guidelines recommend.

“This study further strengthens our current resolve that women need to get screened earlier,” says Dr. Alsheik. “My key takeaway and message to women who see this study is simply don’t panic, but also don’t wait to get your mammogram. I’m sure some mothers, especially those who have had children later in life, will be nervous and fearful when they hear about the study results. But don’t let the findings scare you.  First, some of the main risk factors when it comes to breast cancer are family history, weight and breast density. Second, it’s important that patients realize, the more information we have about the factors that affect a woman’s risk of getting breast cancer, the better. These factors help us determine who to screen and when to screen them. And breast cancer screenings, 3D mammograms in particular, save lives. Instead of inferring that childbirth and breastfeeding have a protective effect, be proactive and get your annual screening.”

Concerned about your breast cancer risk?

Our Breast Health Assessment estimates your five-year and lifetime risks of developing breast cancer.

Time for your annual mammogram?

If you live near the Chicago area or central Illinois, schedule your mammogram online today and get the results without the worry of waiting.