A new study of thousands of women around the world found that rates of deadly ovarian cancer declined by up to 32% for women who used contraceptive intrauterine devices or IUDs.
Led by cancer and family planning doctors at UCHealth University of Colorado Hospital, the study marks the first of its kind to bring together the results of multiple international studies and examine how IUDs affected ovarian cancer rates.
The results, which were released today, appear in the October issue of Obstetrics & Gynecology.
“We know that ovarian cancer is the deadliest of gynecologic cancers. Anything we can do to decrease that risk is very important,” said Dr. Lindsay Wheeler, the study’s lead author and a gynecologic oncology fellow at the University of Colorado Cancer Center on the Anschutz Medical Campus.
Ovarian cancer accounts for more than 22,000 deaths worldwide each year. In the U.S. alone, the National Cancer Institute estimates there will be 22,530 new cases and 13,980 deaths due to ovarian cancer in 2019.
One of the greatest challenges is that there is no way to screen women for ovarian cancer and symptoms are vague, so women often are diagnosed at an advanced stage.
“This is a very important study,” said Guntupalli, director of gynecologic oncology at the University of Colorado Cancer Center. “It’s a meta-analysis, the most powerful of all types of studies we have. It takes data from many different places and pulls all the data together. It’s the first of its kind to look at multiple international sources to see how IUDs affect ovarian cancer.”
The researchers analyzed results of 11 studies from diverse places including China, Vietnam and Italy and found that IUDs were associated with a significant reduction in the incidence of ovarian cancer. The reductions ranged from 15-to-32%.
The women used many different types of IUDs and the study authors were not able to determine how long the women had used the devices. Nor could they determine exactly why the ovarian cancer rates went down.
Wheeler and Guntupalli believe either hormones or the immune environment may play a role.
“Many types of IUDs have hormones in them and exhibit anti-estrogenic effects which may help women who are at high risk for ovarian and uterine cancers,” Guntupalli said. “The second reason was that all the different kinds of IUDs…resulted in some local inflammatory effects. Immune cells increase and are thought to halt the threat of cancer.”
Back in the 1970s, one brand of IUD was deemed unsafe and pulled off the market. Since then, IUDs have had a strong comeback. Doctors say modern IUDs are extremely safe and effective, with more than a 99% success rate at preventing unwanted pregnancies.
“While not every contraceptive is right for every woman, IUDs are in the top tier of contraceptive methods for their convenience, effectiveness, and health benefits. And, we just found another possible exciting health benefit,” said Teal, the family planning expert. “This is a significant association, and it is good news for women.”
In addition to their effectiveness, IUDs are convenient for women because they can work for 7 to 12 years. Women who want to have babies sooner can have them removed any time, Teal said.
In addition to preventing unwanted pregnancies, Teal said it’s important to understand that IUDs and other contraceptives can have “very positive effects on women’s health.”
“Contraception can have very profound effects, not just on quality of life, but also potentially on reduction of mortality,” she said.
Researchers long have known that various birth control methods, including IUDs, reduce the risk of endometrial cancer. A similar meta-analysis recently found that the risk of cervical cancer went down in women who used IUDS. Previous research has shown that tubal ligation and oral contraceptives decrease ovarian cancer rates. And, doctors routinely use IUDs with hormones to treat women with endometrial cancer.
But, said Wheeler: “This study marks the first time researchers also have shown a reduced risk of ovarian cancer with IUDs.”
The study authors say more research is needed both because they included such a broad array of women who had so many different kinds of IUDs, and because they couldn’t determine if the women had IUDs for “10 years or 10 months,” as Guntupalli said.
Even with these shortcomings, Guntupalli said the findings are “incredibly compelling” and doctors should consider the effects on cancer along with other non-contraceptive and contraceptive benefits of IUDs.
“Talk to your physician. Talk to your OBGYN. Determine what the best means of contraception is for you,” Guntupalli said.
This study, along with additional research, could save women’s lives.
As the study authors wrote, “These data suggest a previously unrecognized non-contraceptive benefit of contraceptive IUDs…Given the grave nature of an advanced ovarian cancer diagnosis, even a modest increase in the use of IUDs may lead to a decrease in the incidence of ovarian cancer in a general population of women, leading to a significant population-level effect.”