Primary Peritoneal Cancer

Primary peritoneal cancer is a rare cancer of the peritoneum, a layer of tissue lining the abdomen. People often don’t notice symptoms until the cancer has progressed. As a result, most people are diagnosed with peritoneal cancer at a later stage. The first treatments tend to be surgery followed by chemotherapy or targeted therapy.


What is primary peritoneal cancer?

Primary peritoneal (pair-uh-toh-NEE-ul) cancer is rare cancer that forms in a thin layer of tissue lining your abdomen (belly). This tissue is called the peritoneum (pair-uh-toh-NEE-um).

The peritoneum also covers organs inside your abdomen, including the:

Your peritoneum is made of epithelial cells which protect surfaces of your body. The peritoneum also produces fluid that lets your organs move inside your abdomen.

Primary peritoneal cancer occurs when the cells within the peritoneum grow abnormally.

What are the types of peritoneal cancer?

Healthcare providers classify peritoneal cancer based on where it first occurs:

  • Primary peritoneal cancer starts inside the cells that make up the peritoneum.
  • Secondary peritoneal cancer starts elsewhere in your body and spreads to the peritoneum.

How common is primary peritoneal cancer?

Primary peritoneal cancer is very rare. Providers diagnose fewer than 7 in 1 million cases each year. But those numbers may be somewhat misleading. Researchers estimate that up to 15% of women diagnosed with advanced ovarian cancer may actually have peritoneal cancer.

Who is at risk of getting primary peritoneal cancer?

Women have a higher risk of primary peritoneal cancer than men. Peritoneal cancer risk factors are similar to ovarian cancer and include:

  • Age: Most people diagnosed with primary peritoneal cancer are age 60 and older.
  • Endometriosis: Risk increases if you have endometriosis, when tissue similar to cells that line the uterus grows outside of your uterus.
  • Genetics: Having a first-degree family member (mother, sister or daughter) with peritoneal cancer, fallopian tube cancer or ovarian cancer increases your risk. Women with BRCA1 or BRCA2 gene mutations (changes) also have a higher risk. So do people with genes for Lynch syndrome (a hereditary condition that raises the risk of several types of cancers).
  • Height: Taller people have a higher risk of primary peritoneal cancer.
  • Hormone replacement therapy: Women who use hormone therapy after menopause have an increased risk.
  • Obesity: People with a higher amount of body fat have a higher risk.
  • Reproductive history: People with infertility and/or no biological children may have a higher risk.

How does peritoneal cancer differ from ovarian cancer?

Peritoneal cancer starts in a different place than ovarian cancer. Ovarian cancer usually starts inside the ovaries or in the cells at the far end of the fallopian tubes. Peritoneal cancer forms in the cells lining the inside of your abdomen and covering the organs contained within your abdomen.

People may easily confuse peritoneal and ovarian cancers. The same type of cells (epithelial) line the peritoneum and cover the ovaries. Both cancers spread along the internal lining of the abdomen, which often makes it difficult to detect where cancer started.

People diagnosed with peritoneal cancer are usually older than those diagnosed with ovarian cancer. The prognosis for peritoneal cancer is also worse than that of ovarian cancer.


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Symptoms and Causes

What causes primary peritoneal cancer?

Researchers don’t know exactly why some people develop primary peritoneal cancer. People born with certain gene mutations (changes) have a higher risk of the disease.

What are the symptoms of primary peritoneal cancer?

As with ovarian cancer, people often don’t notice symptoms in the early stages of the disease. If they do, symptoms are often vague. Most people notice symptoms once cancer has advanced (grown).

If someone does have symptoms in the early stages, they may include:

  • Abdominal and/or pelvic pain.
  • Abnormal vaginal bleeding or discharge.
  • Bloating or sense of fullness in the abdomen or pelvis.
  • Bowel changes (increased constipation and/or gas) or rectal bleeding.
  • Frequent urination.
  • Indigestion, loss of appetite or feeling full before you finish eating.
  • Unintended weight gain or weight loss.

As peritoneal cancer grows, additional symptoms may develop, including:


What are the complications of primary peritoneal cancer?

People with advanced peritoneal cancer may have the following complications:

Diagnosis and Tests

How is primary peritoneal cancer diagnosed?

Your healthcare provider will start with a history and physical exam and ask about any symptoms you’re experiencing. If your symptoms point to peritoneal cancer, you may have:

  • Blood tests: These look for a chemical made by certain cancer cells called CA-125. The level of this chemical may be high in people with peritoneal cancer. Blood tests may also look for increased levels of a protein called HE4, which may also be produced by peritoneal cancer cells.
  • Imaging tests: Ultrasound, MRI or CT scan look for tumors. But peritoneal cancer can be hard to see using these tests.
  • Laparoscopy: Your provider can perform a laparoscopy to make a diagnosis. This procedure involves several very small incisions in the abdomen. During the procedure, they can do a biopsy to take a sample of abnormal tissues. These tissues are then examined under a microscope by a pathologist to identify if cancer is present.
  • Paracentesis: If you have ascites, your provider may take a sample of abdominal fluid for testing. Providers often perform peritoneal paracentesis during a laparoscopy.
  • Pelvic exam: An exam of your vagina, cervix, uterus, fallopian tubes, ovaries, and rectum to look for any abnormal areas or lumps.

Special testing considerations

You may be referred to a genetic counselor to discuss genetic testing for certain conditions associated with an increased risk of peritoneal cancer if you have any of the following:

  • First-degree family member (mother, sister, or daughter) with peritoneal cancer, fallopian tube cancer, or ovarian cancer.
  • Family history of BRCA1 or BRCA2 gene mutations.
  • Family history of Lynch Syndrome.


What are the stages of primary peritoneal cancer?

Since most people don’t develop symptoms in the early stages of primary peritoneal cancer, people are typically found to have stage 3 or 4 cancer once they are diagnosed.

Stage 3: Cancer has spread outside of the pelvis or to the lymph nodes located behind the abdomen.

Stage 4: Cancer has spread to organs outside of the abdomen such as the lungs, liver, spleen or to the tissue lining the lungs and chest.

Management and Treatment

How is primary peritoneal cancer managed or treated?

Treatment for primary peritoneal cancer depends on:

Your provider will usually perform surgery as the first treatment. You may have a procedure called cytoreductive surgery. This surgery aims to remove as much cancer as possible. Research shows that outcomes are better when a gynecologic oncologist performs the surgery. These doctors specialize in treating conditions affecting female reproductive organs, including cancer.

Your surgeon may also remove the:

To stop cancer cells from spreading to other areas of the body, your treatment plan may also include:

  • Chemotherapy: Traditional chemotherapy for peritoneal cancer is given through the veins (intravenous) or directly into the abdominal cavity (intraperitoneal). In certain cases, providers may use heated chemotherapy drugs (hyperthermic intraperitoneal chemotherapy or HIPEC). HIPEC is injected into the abdominal cavity immediately after cytoreductive surgery while you are still in the operating room and under anesthesia. In some cancers, HIPEC may be a more effective form of delivering chemotherapy.
  • Targeted therapy: Your provider may use specific drugs to target cancer cells without affecting normal cells.
  • Hormonal therapy: In advanced cases, providers sometimes combine hormonal therapy with chemotherapy. This therapy blocks your body’s natural hormones from reaching cancer cells, preventing their growth.
  • Radiation therapy: Providers rarely use radiation therapy as the first treatment for peritoneal cancer. They may offer radiation to target small areas of cancer that have returned after initial treatment.


How can I reduce my risk?

You may have a lower risk of developing primary peritoneal cancer if you have ever:

  • Breastfed.
  • Given birth.
  • Taken birth control pills.
  • Undergone removal of your fallopian tubes and/or ovaries.
  • Undergone tubal ligation (fallopian tubes tied).

Some people with a strong family history of ovarian cancer or BRCA gene mutations who have a higher risk of developing peritoneal cancer may choose to have their ovaries and fallopian tubes removed. While this procedure reduces the risk of developing peritoneal cancer, it doesn’t completely eliminate it.

Outlook / Prognosis

What is the prognosis (outlook) for people with primary peritoneal cancer?

Since providers usually don’t diagnose peritoneal cancer until a later stage, the prognosis is poor. Cancer often returns after treatment. But getting an earlier diagnosis can help improve outcomes.

About half of people with peritoneal, fallopian tube or ovarian cancer live five years or more after their diagnosis. Younger people tend to live longer, while older people tend to have a worse prognosis.

Survival rates may be higher if:

  • Cancer has not spread to your lymph nodes.
  • You received HIPEC.
  • Your surgeon removed as much cancer as possible.

Several clinical trials are testing new ways to treat peritoneal cancer. New treatments include targeted therapies and immunotherapy. Immunotherapy works by stimulating your immune system to recognize and attack cancer cells within your body.

Living With

How do I take care of myself?

Your provider may suggest seeing a palliative medicine provider (a field of medical care that focuses on addressing and relieving symptoms of a serious illness) to help manage your symptoms from advanced peritoneal cancer. Your care may include:

  • Nausea and vomiting relief.
  • Nutrition consultation to help with loss of appetite and dietary recommendations.
  • Pain management.
  • Paracentesis to remove fluid that has built up in your abdomen (ascites).

How can I best cope with primary peritoneal cancer?

Finding a support group of other people going through treatment can help you feel less alone. Family members can also find support groups to help them better understand what you’re going through.

A note from Cleveland Clinic

Primary peritoneal cancer is a rare type of cancer that occurs in the tissue lining the abdomen. People with peritoneal cancer often don’t experience symptoms until cancer has grown. So, many people are diagnosed with peritoneal cancer at later stages. Promising treatments such as HIPEC and targeted therapies, along with surgery, can improve outcomes. Clinical trials are also underway to discover additional treatment options that can increase survival rates.

Medically Reviewed

Last reviewed on 04/12/2022.

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