Ovarian Cancer Risk Increase with Severe Endometriosis

Endometriosis affects about 11% of reproductive-aged women and involves the growth of tissue similar to the uterine lining outside the uterus, often causing pelvic pain and infertility1 . Recent large-scale studies reveal that women with endometriosis have more than four times the risk of developing ovarian cancer compared to those without the condition1 . This risk is especially pronounced in women with severe forms of endometriosis, such as deep infiltrating endometriosis and ovarian endometriomas, who face nearly a 10-fold increased risk2 .

Endometriosis and Ovarian Cancer Connection

Endometriosis is a chronic condition characterized by the presence of functional endometrial tissue outside the uterine cavity, which can cause lesions on pelvic organs including the ovaries3 . The disease manifests in three main forms: superficial endometriosis, deep infiltrating endometriosis (affecting organs near the uterus like ovaries, bladder, and bowels), and ovarian endometriomas (cysts within the ovaries) 1. Women with endometriosis have a significantly elevated risk of ovarian cancer, particularly for type I ovarian cancers, which include endometrioid, clear cell, mucinous, and low-grade serous carcinomas4 .

A landmark population-based cohort study using data from the Utah Population Database matched 78,893 women with endometriosis to women without the condition in a 1:5 ratio, identifying 597 cases of ovarian cancer4 . This study found:

• Women with endometriosis had a 4.20-fold higher risk of ovarian cancer compared to those without endometriosis4 .
• The risk of type I ovarian cancer was 7.48 times higher in women with endometriosis4 .
• Women with deep infiltrating endometriosis and/or ovarian endometriomas had an 18.96-fold increased risk of type I ovarian cancer4 .
• The risk of type II ovarian cancer, which tends to be more aggressive, was also elevated at 3.72-fold4 .

Women with severe endometriosis are nearly 10 times more likely to develop ovarian cancer than women without the disease. This highlights the importance of tailored counseling and vigilant monitoring for those affected8 .

These findings suggest that the association between severe endometriosis and ovarian cancer risk is as strong as the well-known link between smoking and lung cancer4 . The increased risk is largely driven by type I ovarian cancers, which typically grow more slowly and cause fewer symptoms than type II cancers1 .

The molecular mechanisms underlying this connection may involve genetic mutations such as ARID1A, which are found in both endometriosis lesions and ovarian cancers, suggesting a potential causal pathway5 . However, endometriosis itself is considered a benign condition, though it has the potential for recurrence and metastasis6 .

Women with endometriosis often experience symptoms such as pelvic pain, lower back pain, pain during intercourse, pain during urination or bowel movements, bleeding between periods, and gastrointestinal symptoms like bloating, diarrhea, or constipation2 . These symptoms can overlap with those of ovarian cancer, but endometriosis symptoms tend to fluctuate with menstrual cycles, whereas ovarian cancer symptoms usually worsen progressively2 .

“This study firmly establishes a strong link between endometriosis severity and the risk of developing type I ovarian cancers.”

— Lan Coffman, MD, PhD, University of Pittsburgh School of Medicine2

Managing Endometriosis and Cancer Risk

Although ovarian cancer remains rare even among women with endometriosis, awareness of the increased risk is crucial for early detection and prevention4 . Currently, there are no reliable screening tests for ovarian cancer in the general population, and screening is typically reserved for women at very high risk4 . Common methods to monitor for ovarian cancer signs include pelvic exams, blood tests such as CA-125, and transvaginal ultrasounds4 .

Women with endometriosis should receive counseling about their elevated ovarian cancer risk and strategies to reduce it4 . Clinicians must recognize the connection between endometriosis and ovarian cancer to improve diagnosis and treatment outcomes4 . Unfortunately, symptoms of endometriosis are frequently dismissed or misattributed, leading to underdiagnosis and delayed care4 .

💡 Did You Know?
Endometriosis occurs when the type of tissue that lines the uterus grows outside the uterus. Common symptoms include pelvic pain and infertility1 .

Lifestyle modifications may help reduce the risk of ovarian cancer in women with endometriosis. These include:

• Regular physical exercise, which has been associated with lower cancer risk4 .
• Use of hormonal birth control, which may reduce ovarian cancer risk by suppressing ovulation4 .
• Maintaining a healthy weight and balanced diet, although direct evidence specific to endometriosis-related cancer risk is limited4 .

Women with severe endometriosis, especially those with ovarian endometriomas or deep infiltrating disease, should be closely monitored due to their markedly higher risk of type I ovarian cancer4 . Early intervention and management of endometriosis symptoms can improve quality of life and potentially reduce cancer risk4 .

“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.”

— Jennifer Doherty, PhD, MS, Huntsman Cancer Institute, University of Utah8

• Be aware of the increased ovarian cancer risk, especially with severe endometriosis subtypes4 .
• Discuss ovarian cancer risk and prevention strategies with your healthcare provider4 .
• Undergo regular pelvic exams and appropriate imaging if recommended4 .
• Consider hormonal therapies that may reduce ovarian cancer risk4 .
• Maintain a healthy lifestyle with regular exercise and balanced nutrition4 .