Endometriosis likely poses a heightened ovarian cancer risk, study finds

• Endometriosis is a complex condition that involves uterine-like tissue growing in other areas outside the uterus.
• Researchers are interested in understanding how endometriosis relates to risk for other conditions, including cancer.
• Results of a recent study found that individuals with endometriosis may be at an increased risk for ovarian cancer. Those with ovarian endometriomas, deep infiltrating endometriosis, or both were at the highest level of risk for ovarian cancer.
• Individuals experiencing endometriosis and those potentially at risk for ovarian cancer can seek proper guidance and follow up with specialists.

Endometriosis is a chronic condition that can be difficult to manage and may also increase risks for additional health problems. It occurs when tissue similar to the uterine lining grows outside the uterus, such as in the ovaries or fallopian tubes.

Endometriosis can lead to symptoms like pelvic pain, pain during intercourse, and problems with fertility.

Experts are still working to understand the complexities of endometriosis and how it relates to risks for other conditions, including how it may increase risk for certain cancers.

A study recently published in JAMA examined the relationship between endometriosis and the risk for ovarian cancer.

The study found that individuals with endometriosis had a risk for ovarian cancer that was four times higher than that of women who did not have endometriosis.

Those with specific endometriosis types, like deep infiltrating endometriosis, had an almost 10 times higher risk for ovarian cancer than women without endometriosis.

The results highlight another potential risk factor for ovarian cancer, making prompt follow-up with specialists essential.

Endometriosis and ovarian cancer risk

This study was a population-based cohort study. The research matched 78,476 women with endometriosis with 372,430 women without known endometriosis. Researchers included participants between the ages of 18 and 55 who had at least one endometriosis diagnosis.

Researchers used data from the Utah Population Database , allowing data collection from multiple health records. They collected data on several covariates, including information on reproductive and surgical histories, body mass index (BMI), smoking history, and ethnicity.

The average age of women at first endometriosis diagnosis was 36 years old, and the average follow-up time with participants was 12 years.

Overall, those with endometriosis were at a much higher risk for ovarian cancer than women who did not have endometriosis.

Compared to women without endometriosis, those with endometriosis were over seven times more at risk of developing type 1 ovarian cancer, which included cancer types like endometrioid, clear cell, and mucinous.

These women were also 2.7 times more at risk of developing high-grade serous ovarian cancer.

Women with deep infiltrating endometriosis saw the most significant risk for ovarian cancer. Those who had both deep infiltrating endometriosis and ovarian endometriomas had the second highest risk.

Overall, women with deep infiltrating endometriosis, ovarian endometriomas, or both were almost 10 times more at risk for developing ovarian cancer.

Steve Vasilev, MD , a board-certified integrative gynecologic oncologist and medical director of Integrative Gynecologic Oncology at Providence Saint John’s Health Center and Professor at Saint John’s Cancer Institute in Santa Monica, CA, who was not involved in this research, commented with his thoughts on the study’s findings to Medical News Today .

According to him:

“This population-based cohort study adds substantial evidence to a growing body of research, including epidemiologic and histopathologic data, which indicates a strong association between endometriosis and specific subtypes of ovarian cancer […] This helps solidify the concern that, in any given individual, endometriosis may progress to certain types of ovarian cancer or stimulate malignant degeneration. Even though the absolute risk is felt to be very low among the millions of women with endometriosis, it is very important to consider because the type of surgery that may be required is different. When cancer is known to be present, or strongly suspected, a cancer specialist (gynecologic oncologist) should be involved.”

How accurate is this study?

Nevertheless, this research has several limitations that could have affected the study’s results. First, it only included participants in a specific age range from one state in the United States, making it difficult to generalize the results.

Second, there was a risk of misclassification of endometriosis due to factors, such as the difficulty of correctly diagnosing endometriosis. While the data compared women with endometriosis to those with no known endometriosis, it is still possible that some women in the control group had endometriosis and had just not been diagnosed.

There is also the possibility researchers misclassified ovarian cancer histotypes, body mass index (BMI), and smoking. Researchers also lacked data on hysterectomies and oophorectomies that happened outside of Utah facilities or other care that occurred outside of the state. Researchers also lacked data on the use of oral contraceptives and gonadotropin-releasing hormone agonists.

Because a diagnosis of endometriosis is often delayed, researchers did assume that those who received an ovarian cancer diagnosis on their index date had actually had an endometriosis diagnosis before cancer onset.

Regardless, the results highlight new questions and areas for research and another potential factor to consider in clinical practice.

Diana Pearre, MD , a board-certified gynecologic oncologist at The Roy and Patricia Disney Family Cancer Center at Providence Saint Joseph Medical Center in Burbank, CA, who was not involved in the research, noted that “[t]he problem with this study is that we do not know the denominator.”

She cautioned that:

“There are plenty of people living with endometriosis who are asymptomatic and may not be seeking treatment/having surgery. Studies like this make us consider, as clinicians and surgeons, whether we should be offering prophylactic surgery for women living with endometriosis. I think without knowing the clear absolute risk of cancer with endometriosis — evidenced by not knowing exactly how many people live with it — we cannot make such a blanketed recommendation.”

“Our counseling for surgical treatment for symptomatic endometriosis, however, should include a very thoughtful discussion with the patient about this association that we are seeing in these large population based studies that there is a definite association between endometriosis and ovarian cancer,” Pearre advised.

How to reduce ovarian cancer risk

Overall, the study highlights endometriosis as a potential risk factor for ovarian cancer. It highlights exploring ways to reduce risk and seeking proper follow-up with specialists.

Unfortunately, there are no screening tests in place that make it easy to detect ovarian cancer, making follow-up even more critical. Vasilev noted that:

“Currently, there is no reliable method recommended to screen for any type of ovarian cancer. With the advent and growth of understanding about molecular mechanisms underlying the disease, this will hopefully change soon. However, the more there is a family history of cancer it is prudent to consider genetic counseling and appropriate testing.”

Some possible ways to reduce the risk of ovarian cancer include using birth control pills for 5 years or longer, giving birth, and breastfeeding.

There is also the option of undergoing surgical removal of the ovaries or other organs in certain situations. All options for reducing the risk of ovarian cancer should be thoroughly discussed with appropriate specialists.

Rikki Baldwin, DO , an obstetrician-gynecologist with Memorial Hermann, who was likewise not involved in the recent study, also noted that self-care measures are “paramount” to reducing any type of cancer risk.

She advised that “[w]omen should eat a well-balanced diet, exercise regularly, avoid smoking and excessive alcohol use, and have regular visits with their primary physician.”

“Symptoms of ovarian cancer are vague, so it is very important to pay attention and notify your physician if there are new and abnormal symptoms like abdominal pain, bloating, nausea, decreased appetite, etc,” noted Baldwin.