Giving Birth Before Age 20 Cuts Breast Risk By 50%, And A Drug May Be Able To Mimic That
Studies have shown that giving birth before the age of 20 can significantly reduce a woman’s risk of breast cancer. A Harvard University study of 17,000 women from countries with low, medium, and high breast cancer rates found that women who had a child before age 18 cut their breast cancer risk by 60% compared to women who had their first baby after age 35. Other studies have found that women cut their risk by 50%. It’s a significant form of protection.
However, many women are now delaying childbirth later than ever to make room for personal accomplishments, careers, or because they simply can’t afford it. Other women are forgoing having biological children altogether.
The natural protection that having a baby at a young age offers intrigued Jose and Irma Russo back in the 1970s. They were interested in determining the biological basis for this protection and worked together on that research for decades.
The link between breast cancer and reproduction isn’t simple, and a woman’s breast cancer risk relies on multiple factors. But the Russos discovered a lot over the course of their research.
“We are very near to having the final answer and we worry that if we talk too much, it could fall apart,” Russo said. “But the idea is to produce the same changes as pregnancy — without pregnancy.”
The Russos were both born in Argentina and then moved to the U.S. in 1971 and began a breast cancer research lab. Other researchers had theorized about the link between pregnancy and breast cancer risk, but the Russos found actual evidence, using cells and animal experiments to reach their conclusions.
They found that a woman’s mammary glands fully mature when full-term pregnancies trigger the growth of milk ducts. When the glands mature at a very young age, the chance of genetic damage to the cells that can be copied into new cells when they divide is significantly reduced.
In the course of the their studies, the Russos found that hCG (human chorionic gonadotropin) prevented rats from developing breast cancer after they were exposed to cancer-causing elements. hCG is a hormone the body releases after implantation of the egg to maintain pregnancy. It’s also what most pregnancy tests measure to find out if a woman is pregnant or not.
They also identified 43 genes that are responsible for breast maturation. Some of these genes were also responsible for protecting a cell’s DNA from damage. They tightened up a cell’s nuclear DNA, something called “chromatin remodeling. The Russos found that pregnancy made the coiling in these genes even more compact, providing even more protection.
Sadly, Irma passed away from ovarian cancer in 2013. Initially, Jose thought he wouldn’t be able to continue the work without her. But the next year, he began working with Herman Depypere, an obstetrician-gynecologist at Ghent University Hospital in Belgium.
The clinical trial they led and their findings were published in the peer-reviewed journal Breast Cancer Research in 2019 and titled “Genomic Signature of Parity in the Breast of Premenopausal Women.”
They gathered 35 childless women who were ages 18 to 30 and who had a BRCA1 or BRCA2 gene mutation. The women were injected with a fertility drug typically used to trigger ovulation, called Ovitrelle. It’s a type of synthetic hCG. The women were injected three times a week for three months. No side effects or other problems arose during those three months.
This trial has helped push Russo one step closer to proving that the protection offered by pregnancy can be artificially triggered. However, even if the hCG causes the same changes in cells that actual pregnancy does, these women need to be followed for years to determine if it actually helped to prevent breast cancer. Additionally, larger trials that include women without any BRCA mutation would also need to be done.
Russo thinks his research is very promising.
“I would like this to be my legacy,” he said. “I am 77. I don’t know how long I will keep going. But the idea that we can confer protection without the necessity of childbirth is exciting. All we can do is learn from nature.”