A 2024 study published in the Journal of the American Medical Association (JAMA) found that women with endometriosis have four times higher risk of developing ovarian cancer than those without endometriosis [1]. The risk increase was the most dramatic in women with ovarian endometriomas or deep infiltrating endometriosis (DIE). But how did researchers even know that endo and ovarian cancer might be related?
Women with endometriosis—a condition in which tissue similar to the endometrial lining is found outside of the uterus—may experience severe menstrual cramps, pelvic pain, and infertility. Despite the fact that 10-15% of women of childbearing years likely have it, formal diagnosis requires surgical evaluation [2]. This may explain why it can take an average of 7 years for women with endo to actually receive a diagnosis [2].
Researchers already knew endo can increase risks of reproductive cancers like endometrial and breast cancer [3]. With this in mind, the 2024 JAMA study set out to identify whether there was a connection between endometriosis and ovarian cancer as well.
What did the researchers study?
Researchers from several universities worked together under Dr. Karen Schliep to conduct a population-based cohort study evaluating whether or not endometriosis impacts the risk of developing ovarian cancer. They used the Utah Population Database to identify almost 80,000 women ages 18-55 who were diagnosed with endometriosis, and compared them with roughly 380,000 women without the diagnosis. Of those roughly 460,000 women, an electronic medical records search showed approximately 600 cases of ovarian cancer.
The data suggested that women with endometriosis are over four times more likely to develop ovarian cancer than those without it [1]. Women with endometriosis are seven times more likely to develop a slower-growing form, known as type 1 ovarian cancer [1].
Ovarian cancer risk depends on the type of endometriosis
The study categorized the various types of endometriosis as “superficial endometriosis, ovarian endometriomas, deep infiltrating endometriosis, or other.” Superficial endometriosis is found on the soft membrane that makes up the abdominal cavity, and may be the most common type of endometriosis. Endometriomas are cystic lesions caused by endometriosis that are most often found on the ovaries [4]. Deep infiltrating endometriosis is found on major organ systems like the bladder, bowels, or ovaries.
For women with ovarian endometriomas or deep infiltrating endometriosis (DIE), the risk of ovarian cancer was exceptionally higher than the group without endometriosis. Their risk of ovarian cancer was nearly ten times higher than their peers without endo. The increased risk of ovarian cancer in women with endometriomas or DIE was so noteworthy that Dr. Schliep compared it to the linkage between smoking and lung cancer [1].
The increased risk of ovarian cancer in women with endometriomas or DIE was so noteworthy that Dr. Schliep compared it to the linkage between smoking and lung cancer [1].
How much more likely are women with endo to get ovarian cancer than women without it?
Previous studies supported the connection between endometriosis and an increased risk of developing ovarian cancer, especially type 1 ovarian cancer varieties [5]. When we say one person’s risk is two times higher or ten times higher than another’s, that’s called relative risk. However, the absolute risk, the likelihood of actually developing ovarian cancer, remains low, even for women with endometriosis. One out of every 76 women in the general population is likely to develop ovarian cancer [6]. For those with endometriosis, the likelihood is one out of 50 [6].
What are the symptoms?
Ovarian cancer symptoms may be vague and can mimic gastrointestinal issues like irritable bowel syndrome, or even endometriosis symptoms. According to Johns Hopkins Medicine, ovarian cancer may feel like “abnormal vaginal discharge or bleeding after menopause, bloating or swollen feeling in the stomach, feeling full very soon after starting to eat, new urinary frequency, new constipation or other changes in bowel movements, discomfort or pain in the pelvic area, abdomen or lower back, fatigue, unexplained weight loss.”
How do you diagnose ovarian cancer?
At the moment, there is no easy way to diagnose ovarian cancer [7]. If your doctor suspects you might have ovarian cancer, he or she may utilize a combination of pelvic exam, imaging such as CT scan or MRI or ultrasound, and blood tests. Sometimes cancer is only diagnosed via biopsy after ovarian surgery. Research in this area needs to continue in order to find effective ways to detect and treat it.
Could endo surgery decrease ovarian cancer risk?
Researchers don’t yet know whether having endometriosis excision surgery might impact ovarian cancer risk. Could removal of inflammatory endometriosis lesions decrease risk? Further research is needed to answer this question, and it will take time since ovarian cancer is both less common and less studied than, for example, breast cancer.
If you have endometriosis, how can you reduce your ovarian cancer risk?
If you have endometriosis, the 2024 JAMA study on endo and ovarian cancer risk is likely of more interest to your doctor or midwife than to you as an individual. The results suggest that on a broad scale, healthcare professionals may need to be screening women with endo for ovarian cancer risk. But if you’re wondering what you can personally do to lower your risk, here are some ideas.
Currently, the only things found to reduce the risk of developing ovarian cancer are pregnancy and childbirth, breastfeeding, removing the ovaries, or being on hormonal birth control for more than five years. As women consider these options, they should keep in mind that there are risks to these approaches as well. For instance, removing the ovaries significantly increases one’s risk for cardiovascular disease, and being on birth control increases the risk of developing other types of cancer (and breast cancer, as one example, is more likely to be fatal than ovarian cancer) [6].
Until we know more about ovarian cancer prevention, practicing simple habits that may reduce the risk of developing any form of cancer are a good first step. Some of these practices include making intentional, healthy dietary choices, reducing chemical and toxin exposure, prioritizing quality sleep, and incorporating exercise like walking into daily life [8][9].
