Published Apr 22, 2020
There have been several studies indicating that breastfeeding can reduce a woman’s risk of breast cancer, but now, a new study published in JAMA Oncology, is pointing to a reduction in overall ovarian cancer risk as well. The new research finds that breastfeeding can reduce the risk of the deadliest subtype of invasive epithelial ovarian cancer, called “high-grade serous.”
The reduction in risk stems from the interruption of a woman’s regular ovulation, according to Dr. Dana Chase, a gynecologic oncologist at Arizona Oncology. However, the reason ovulation and ovarian cancer risk are linked is still unknown.
“The association of any interruption in ovulation (birth control pills, pregnancies, breastfeeding, for example) has been associated with decreased rates of ovarian cancer,” Dr. Chase says. “The reason for this is unknown, but has been reported consistently in the literature.”
The new research aimed to clarify whether the reduction in ovarian cancer risk among mothers was simply because they had children, or if breastfeeding played a role in risk reduction as well. Researchers pooled analysis of 9,973 women with ovarian cancer and 13,843 women without ovarian cancer from a total of 13 case-controlled studies. They found that breastfeeding was linked to a 24% reduction in risk of developing invasive epithelial ovarian cancer. What’s more, the longer a woman breastfed, the greater reduction in risk.
While the new research found breastfeeding for a longer period of time resulted in a larger risk reduction, the act of “having breastfed was associated with reduction in risk of all invasive ovarian cancers, particularly high-grade serous and endometrioid cancers,” study authors say. For example, breastfeeding with one child for a duration of one to three months was associated with an 18% lower risk. If a woman breastfeeds for 12 months or more, that risk reduction rises to 34%.
It’s already been well-documented that having children can reduce a woman’s risk of ovarian cancer. The new research makes the distinction that breastfeeding also plays a role. But there are other ways women can reduce their risk of the disease.
“We know that having children can actually reduce the risk. Taking the birth control pill will reduce the risk,” Dr. Jonathan Berek, Director of Stanford Women’s Cancer Center, told SurvivorNet in a previous interview. “If women have taken the birth control pill for up to five years and have had two children, they may reduce their risk by as much as 70% of getting the most common type of ovarian fallopian tube cancer. Those are very important things to know.”
Dr. Jonathan Berek discusses how women can reduce their risk of ovarian cancer.
“Those are two of the things that people actually can do if they’re able to have children and if they have a choice of what kind of birth control to use, then the oral contraceptive would be the contraceptive of choice to reduce the risk,” Dr. Berek added.
The ovarian cancer risk reduction when it comes to childbirth has been observed in several studies. Research from Oxford University in 2015 found that women with one child reduced their risk by about 20%, and the risk continued to decrease with every child after the first by 8%. This new research, though, is key in identifying that breastfeeding — independent of pregnancy alone — will also reduce a woman’s risk of being diagnosed with the disease.