Roughly 1 in 100 women will develop ovarian cancer in her lifetime. Though it’s not as common as other types of cancer, it’s much more deadly. Despite accounting for only 1% of cancer cases each year in the United States, it makes up 2% of deaths. The five-year survival rate is also only 50%. New research shows that women with a common reproductive health issue may also be at a substantially increased risk of developing the disease.

Research recently published in the Journal of the American Medical Association examined the link between ovarian cancer and endometriosis, which impacts about 10% of women of childbearing age across the globe. While past studies have shown that endometriosis is associated with a higher ovarian cancer risk, this particular study looked at different forms of each disease to get a better idea of the risk.

The team – from the Huntsman Cancer Institute, the University of Utah’s school of medicine, and Boston University’s school of medicine – used the Utah Population Database to compare nearly 79,000 women with endometriosis to more than 300,000 of their peers without the disease. The average age of diagnosis for these women was 36. Out of all the women included, 597 had ovarian cancer.

The study showed that women with any type of endometriosis had a 4.2 times higher risk of developing ovarian cancer than women without the condition. However, risk varied based on the type of endometriosis, all types of which involve lining similar to uterine lining growing elsewhere in the body. For women with ovarian endometriomas, or cysts on the ovaries, and/or deep infiltrating endometriosis, where the lining grows on organs outside the uterus, there was a nearly 9.7 times higher risk of developing ovarian cancer, as well as a nearly 19 times higher risk for type I ovarian cancer. The researchers say that compares to the impacts of smoking on lung cancer.

Dr. Jennifer Doherty, study co-author and co-leader of the Cancer Control and Population Sciences Program at Huntsman Cancer Institute, says, “These are really important findings. This impacts clinical care for individuals with severe endometriosis, since they would benefit from counseling about ovarian cancer risk and prevention. This research will also lead to further studies to understand the mechanisms through which specific types of endometriosis cause different types of ovarian cancer.”

This adds another complication to endometriosis, which can also involve severe periods, pain during sex and in the pelvic area, bloating, and infertility. The disease also produces lesions in the ovaries, fallopian tubes, and behind the uterus.

Despite the findings, though, researchers believe the study may be helpful for patients, in order to have more informed conversations with their doctors. It could also lead to targeted screening and prevention studies.

Dr. Karen Schliep, senior author and associate professor of public health at the University of Utah, says, “The big question for women is ‘what can I do about it?’ This is important data for women to have as they're weighing what kind of treatments they should maybe undergo to avoid any kind of disease down the road. I’m very passionate about giving women the right information and then having them be able to make shared decisions with their physician.”