Epithelial Ovarian Cancer

What is epithelial ovarian cancer?

Epithelial ovarian cancer is the most common type of ovarian cancer. This cancer develops in the epithelial tissue, a thin lining that covers the outside of an ovary.

Cancer may also form in the lining of a fallopian tube. Or it can begin in the peritoneum, the tissue that covers your abdominal organs.

Medical experts consider fallopian tube cancers and primary peritoneal cancers to be epithelial ovarian cancers. The diseases share many similarities, including treatments.

How common is epithelial ovarian cancer?

Ovarian cancer is the second most common cancer that affects the female reproductive system (gynecological cancer). Uterine (endometrial) cancer is the most common. A female has a 1 in 78 lifetime risk of getting ovarian cancer.

In 2021, more than 21,400 people learned they had ovarian cancer. Epithelial ovarian cancer accounts for more than 9 in 10 of these cases. More than half of epithelial ovarian cancer cases affect people over 65.

What are the types of epithelial ovarian cancer?

About 3 out of 4 epithelial ovarian cancers are high-grade serous ovarian carcinomas (HGSOC). Cancer cells that are high-grade grow and spread faster than those that are low-grade.

Experts believe HGSOC grows slowly at first. It starts in your fallopian tubes. It may take up to six and a half years to reach your ovaries.

Once the cancer is in your ovaries, it spreads quickly. The cancer often affects your peritoneum and other parts of your body. Nearly 70% of HGSOCs are stage 3 or 4 at the time of diagnosis. This means the cancer has spread outside of the original tumor and is now metastatic cancer.

Less common types of epithelial ovarian cancers include:

• Endometrioid carcinoma: This cancer is more common in people who have endometriosis. It affects the endometrium, the inner lining of your uterus. It responds better to chemotherapy than some other types do.
• Low-grade serous ovarian carcinoma (LGSOC): This slow-growing cancer affects people at a younger age (between 45 and 57). It accounts for about 10% of epithelial ovarian cancers. The disease is often advanced at the time of diagnosis and doesn’t respond well to chemotherapy. Low-grade carcinomas grow slowly. They’re unlikely to become high-grade cancers.
• Mucinous carcinoma: These tumors are more distinct and respond well to treatments. They tend to be large (around 8 inches or 20 centimeters). Typically, they only affect your ovaries.
• Ovarian clear cell carcinoma (OCCC): People who are Asian and people with endometriosis are most at risk for this cancer. The disease is often advanced at diagnosis. It doesn’t respond well to chemotherapy.
• Primary squamous cell carcinoma (SCC) of the ovary: SCC typically develops from benign (noncancerous) conditions. It may form from ovarian cysts, endometriosis or Brenner tumors (solid, abnormal growths on your ovaries). It responds well to treatment when caught early.

What causes epithelial ovarian cancer?

Most cancers, including epithelial ovarian cancers, develop for no known reason. Research now suggests that many ovarian cancers actually start in cells at the end of the fallopian tubes. Then, they spread to the ovaries.

What are risk factors for epithelial ovarian cancer?

More than half of ovarian cancer diagnoses occur in people over 65 who have gone through menopause.

Certain factors may increase your risk of ovarian cancer, such as:

• Family history of ovarian cancer, breast cancer or colorectal (colon) cancer.
• Inheriting a change (mutation) to the BRCA gene.
• Inheriting a gene linked to family cancer syndromes like Lynch syndrome.
• Hormone therapy for menopause symptoms.
• Having a baby after age 35 or never having a full-term pregnancy.
• Carrying extra weight (obesity).

What are the symptoms of epithelial ovarian cancer?

Epithelial ovarian cancer rarely causes symptoms in its early stage. Symptoms become more noticeable as the disease progresses. As it spreads into your peritoneum (tissue that covers your abdominal organs), fluid accumulates in your abdomen (ascites).

You may also experience:

• Abdominal pain.
• Difficulty eating or feeling full quickly.
• Nausea and vomiting.
• Bloating.
• Pelvic pain.

Less common symptoms include:

• Urgent need to urinate (urge incontinence) or frequent urination (overactive bladder).
• Vaginal bleeding.

How is epithelial ovarian cancer diagnosed?

There aren’t any screening tests to detect ovarian cancer early. You might have tests only if you have symptoms or are high risk. Your healthcare provider may start by performing a pelvic exam to check for unusual growths or enlarged organs.

You might have a CA-125 blood test to check for elevated levels of a protein called cancer antigen 125 (CA-125). High levels may mean you need more testing.

These imaging tests help detect ovarian cancer:

• Transvaginal ultrasound.
• CT scan.
• MRI.
• Positron emission tomography (PET) scan.
• Chest X-rays (to look for metastatic cancer to the lungs).

You may also undergo a laparoscopy. This less invasive procedure lets your surgeon view your reproductive organs. Your healthcare provider may take tissue samples of a tumor to biopsy for cancer cells. A biopsy is the only way to definitively diagnose ovarian cancer.

What are epithelial ovarian cancer stages?

Cancer staging helps healthcare providers track a cancer’s growth. It tells your healthcare provider if the cancer has spread and affects treatment decisions. The same tests that diagnose cancer can determine the cancer stage.

There are four stages of ovarian cancer. Some stages have sub-stages. A higher stage number reflects a more advanced cancer. Ovarian cancer stages include:

• Stage 1: Cancer is in one ovary or one fallopian tube.
• Stage 2: Cancer has spread to your uterus or your peritoneal cavity.
• Stage 3: Cancer has spread outside of your pelvis to other organs, lymph nodes or both.
• Stage 4: Cancer cells are in fluid surrounding your lungs, lymph nodes in your groin, organs or other parts of your body.

Can epithelial ovarian cancer be cured?

Surgeons perform debulking surgery, which removes as much of the tumor as possible, followed by chemotherapy. Most people are initially cured, but the majority will get it again later.

People with early-stage cancer may choose to remove only the diseased ovary and fallopian tube.

People with advanced cancers often undergo debulking surgery to remove:

• Both fallopian tubes and ovaries (bilateral salpingo-oophorectomy).
• Uterus (hysterectomy).
• Omentum or fatty tissue covering your abdomen (omentectomy).
• Nearby lymph nodes.
• Any other diseased areas (like your small intestine, large intestine or spleen).

What are other epithelial ovarian cancer treatments?

Depending on the cancer type, you may get one or more of these treatments after surgery:

• Chemotherapy to kill cancer cells. Treatments include platinum compounds (carboplatin) and paclitaxel (Taxol®) or docetaxel (Taxotere®).
• Intraperitoneal chemotherapy to treat stage 3 ovarian cancer by injecting cisplatin and paclitaxel directly into your abdominal cavity through a surgically placed catheter (thin, hollow tube).
• Targeted therapies like bevacizumab (Avastin®) to stop cancer cells from growing and multiplying.
• Radiation therapy to destroy cancer cells with high-energy X-ray beams.

Can you prevent epithelial ovarian cancer?

Studies show that people who take the pill (a form of hormonal birth control) for five or more years may cut their risk of ovarian cancer in half.

Certain surgical procedures may also lower cancer risk. Surgery to prevent cancer is called prophylactic surgery. This involves the removal of your fallopian tubes and ovaries with or without a hysterectomy. This is considered in people who are at high risk due to family history (like those who have a BRCA mutation or Lynch syndrome). However, experts advise taking these actions only if medically necessary. Removing your ovaries can bring on early menopause, which has its own effects on your body.

These procedures don’t completely eliminate cancer risk. Some people may already have undetected cancer when surgery takes place.

People with BRCA gene mutations can still get primary peritoneal cancer after removal of their fallopian tubes and ovaries. Ask your healthcare provider if you should have a BRCA test to find out if you have the BRCA gene.

What is the outlook for people with epithelial ovarian cancer?

More than 13,000 people die from ovarian cancer every year. It’s the fifth leading cause of cancer deaths among people assigned female at birth (AFAB). But promising new treatments are under development in clinical trials. And researchers are making progress in detecting the disease earlier.

When epithelial ovarian cancer is detected before it spreads, the five-year survival rate is more than 90%. This number drops to about 30% when the cancer has spread (metastasized).

Many factors affect a cancer prognosis, including:

• Cancer spread.
• Effectiveness of treatments.
• Location, size and number of tumors (cancer stage).

When should I call the doctor?

Call your healthcare provider if you experience:

• Changes in frequency or urgency of urination.
• Loss of appetite or feeling of fullness.
• Unexplained abdominal or pelvic pain.

What should I ask my healthcare provider?

You may want to ask your healthcare provider:

• Should I have a BRCA test?
• What type of epithelial ovarian cancer do I have?
• What’s the best treatment for me?
• What are the treatment side effects?
• Am I at risk for metastatic cancer? How can I lower this risk?
• Should I look out for signs of complications?

What is the most aggressive form of ovarian cancer?

HGSOC (high-grade serous ovarian cancer) is a very aggressive ovarian cancer. The cancer grows slowly in your fallopian tubes at first. But it then spreads rapidly once it reaches your ovaries. Unfortunately, most people with HGSOC have advanced (metastatic) ovarian cancer by the time they get a diagnosis.

Is it possible to have benign (noncancerous) epithelial ovarian tumors?

Yes. In fact, most epithelial ovarian tumors aren’t cancerous. Some tumors are borderline tumors or atypical proliferating tumors. They used to be known as low malignant potential tumors.

In borderline tumors, abnormal cells grow into the epithelial tissue but not your ovary’s supporting tissue (stroma). These cells usually stay in your ovary and rarely become cancer. When cancer occurs, 3 out of 4 cases are stage 1 (confined to your ovary and more treatable). These tumors tend to affect younger people.

A note from Cleveland Clinic

Epithelial ovarian cancer is the most common ovarian cancer. It includes fallopian tube cancer and primary peritoneal cancer. Ovarian cancers rarely cause symptoms in the early stages. The disease often spreads undetected by the time of diagnosis. This is especially true for HGSOC, the most common epithelial cancer. If you’re at high risk for ovarian cancer, ask your healthcare provider if preventive (prophylactic) measures are right for you.