Endometriosis can slightly increase a person’s chances of developing ovarian cancer. However, the majority of people living with endometriosis will never develop this type of cancer. Additionally, certain endometriosis treatments may help lower a person’s risk of developing ovarian cancer.

Ovarian Cancer Risk in Endometriosis

Ovarian cancer develops when cancer cells form in the ovary. Ovaries are organs that produce egg cells and hormones within the female reproductive system. Cancers of the fallopian tubes (the tubes that connect the ovaries to the uterus) and peritoneum (the inner lining of the abdomen) are also grouped with ovarian cancer. Cancer that begins in the fallopian tubes or peritoneum often spreads to an ovary and vice versa.

About 1.2 percent of women within the general U.S. population are diagnosed with ovarian cancer at some point in their lives, according to the National Cancer Institute's Surveillance, Epidemiology, and End Results Program. People with endometriosis have a slightly higher lifetime risk of developing ovarian cancer.

Many researchers have tried to determine how often ovarian cancer occurs in people with a diagnosis of endometriosis. They have measured this effect in different ways in various groups of people, leading to different estimates. Some research has shown that 1.8 percent of women with endometriosis will develop ovarian cancer — only a very small increased risk compared to other women. Other studies have reported that ovarian cancer is diagnosed in up to 17 percent of women with endometriosis.

Certain factors may make a person with endometriosis more likely to develop ovarian cancer, including:

• Older age
• Having higher levels of a protein called CA-125 in the blood
• Having endometriosis for more than five years
• Having very large endometriosis lesions (tissue growths)

Ultimately, endometriosis leads to a small increased risk of ovarian cancer. The majority of individuals with a history of endometriosis don’t develop cancer.

Ovarian Cancer Prognosis in Endometriosis

People with endometriosis who develop ovarian cancer are usually younger and develop their cancer at an earlier stage. This may be because those with symptomatic endometriosis are under the care of physicians monitoring their symptoms and any endometrioma masses they may have. This often translates to a better prognosis (outlook).

Additionally, people with endometriosis are more likely to develop types of ovarian cancer that are easier to treat. In particular, their risk of developing endometrioid carcinoma and clear cell carcinoma is higher. These two ovarian cancer subtypes are often detected early and usually come with a better outlook than other types. However, it is still possible for people with endometriosis to develop other, more serious types of ovarian cancer.

Ovarian Cancer Risk and Endometriosis Treatments

Although endometriosis can raise a person’s chances of developing ovarian cancer, some treatments for endometriosis can also lower the risk.

Hormone Treatments

Some people with endometriosis use hormone therapy, including hormonal birth control, to eliminate or reduce hormone levels. These treatments often help relieve the symptoms of endometriosis. Some are also helpful for those worried about ovarian cancer risk — oral contraceptives (birth control pills) can cut a person’s risk of ovarian cancer in half.

Surgery

In the past, surgery to remove the reproductive organs was also recommended for people with endometriosis. Options included an oophorectomy (removal of the ovaries), salpingectomy (removal of the tubes), and a hysterectomy (removal of the uterus). However, these surgeries come with risks. An oophorectomy can cause early menopause for those who still have their periods, which may lead to a higher risk of conditions like heart disease. Hysterectomies cause infertility.

Although removing the ovaries and fallopian tubes will prevent ovarian cancer, the chances of developing this type of cancer are not very high. Many doctors think that the risks are not worth the benefits.

Some MyEndometriosisTeam members have had conversations with their doctors weighing the benefits and risks of removing the ovaries. One member said that they had hoped their doctor would remove both ovaries in addition to their uterus, but their doctor recommended against it. “I initially preferred to take everything out, not only because of endometriosis but also due to the risk of cancer (family history of uterine and breast cancer). However, my doctor said there were side effects of having surgical menopause (cardiovascular disease, osteoporosis), so he wants to leave one ovary if possible.”

Another member said that keeping both ovaries made the most sense based on their risk levels. “I have a long history of heart disease and osteoporosis, but no ovarian cancer. So when I had my excision surgery with hysterectomy, we left my ovaries.”

If you are worried about ovarian cancer, have a conversation with your doctor about your personal and family health history to better understand the risk. You may want to ask if an oophorectomy is worth the side effects.

Reducing Ovarian Cancer Risk

Although it’s not possible to completely prevent ovarian cancer, you can reduce your risk of developing the condition. Paying attention to risk factors, educating yourself about the signs and symptoms of ovarian cancer, and keeping up with regular health visits can help.

Eliminating Ovarian Cancer Risk Factors

Several factors besides endometriosis affect your risk of ovarian cancer. You can’t change some risk factors, such as your age or the genes you have. However, you have more control over others. Lifestyle changes that may help with cancer prevention include:

• Eating a balanced diet containing a variety of foods and nutrients
• Limiting how much alcohol you drink
• Exercising regularly
• Keeping your weight at a healthy level
• Avoiding smoking
• Not using hormone replacement therapy after going into menopause — if needed, use it for the shortest amount of time possible

Understanding Ovarian Cancer Symptoms

People who catch their ovarian cancer early often have better outcomes. You can reduce your risk of a poor prognosis by knowing the symptoms of ovarian cancer and quickly checking on any health changes.

The most common ovarian cancer symptoms to watch out for include:

• Stomach or pelvic pain
• Bloating
• More frequent urination
• Feeling full after eating only a little

Keeping Regular Doctor’s Visits

Regular pelvic exams can help your doctor make sure your reproductive system is healthy. However, pelvic exams don’t always catch early-stage ovarian cancer.

Screening tests may sometimes detect other types of cancer while they are in the early stages. However, screening tests are not that effective for ovarian cancer. Screening may include an ultrasound to view the ovaries or a blood test to look for CA-125. These tests don’t work well to catch ovarian cancer early, and they often uncover other abnormalities that end up not being cancer. These findings sometimes result in people undergoing extra procedures that aren’t necessary and carry a risk of causing injury.

If you are worried about ovarian cancer risk, talk to your doctor. Your doctor can help you understand your risk level based on your personal and family history and may be able to recommend other strategies for managing risk. Keep in mind that the risk of ovarian cancer for those with endometriosis is not much different than it is for other individuals.

Talk With Others Who Understand

MyEndometriosisTeam is the social network for people with endometriosis. More than 121,555 members come together to ask questions, give advice, and share their stories with others who understand life with endometriosis.

Are you worried about ovarian cancer while living with endometriosis? Share your experiences in the comments below, or start a conversation by posting on MyEndometriosisTeam.