Primary peritoneal cancer

Primary peritoneal cancer (PPC) is a rare cancer. It starts in the thin layer of tissue lining the inside of the tummy (abdomen). This tissue lining is called the peritoneum. 

PPC cells are the same as the most common type of ovarian cancer cells. This is because the lining of the abdomen and the surface of the ovary come from the same tissue when we develop from embryos in the womb. So doctors treat PPC in the same way as ovarian cancer.

What is the peritoneum?

The peritoneum is a layer of thin tissue that lines the inside of the tummy (abdomen). It covers all of the organs within it, such as the bowel and the liver. It protects the organs and acts as a barrier to infection. It has 2 layers:

• the parietal layer which lines the abdominal wall 
• the visceral layer which covers the organs 

There is a small amount of fluid between the two layers, which separates them and allows them to slide over each other. This fluid allows us to move around without causing any friction on the layers.

What is primary peritoneal cancer?

PPC mainly affects women. It's very rare in men. Most people are over the age of 60 when they are diagnosed.

Doctors think that most PPCs start in the cells at the end of the fallopian tube. These early cancer cells then spread to the peritoneum and grow. This type of cancer is called high grade serous cancer.

Symptoms

The symptoms of PPC can be very unclear and difficult to spot. They include:

• a swollen tummy (abdomen)
• tummy pain
• feeling bloated
• constipation or diarrhoea
• feeling or being sick
• loss of appetite 
• urinary symptoms such as needing to pee more often or you need to pee urgently

The symptoms of PPC are very similar to the symptoms of ovarian cancer.

Tests to diagnose primary peritoneal cancer

You might have the following tests to diagnose primary peritoneal cancer. These are the same as the tests you might have for ovarian cancer. They include:

• pelvic examination
• blood tests
• ultrasound scan
• CT scan
• MRI scan
• laparotomy

Stages of primary peritoneal cancer

The stage of a cancer shows how big it is and whether it has spread. This helps doctors to decide which treatment you need.

The staging system for PPC is the same as for ovarian cancer, but there are no early stages. PPC is always either stage 3 or stage 4. This is an advanced cancer.

Treatment for primary peritoneal cancer

The treatment you have depends on a number of things including:

• the size of your cancer
• where the cancer is in the abdomen, and if it has spread further away
• your general health

The treatment for PPC is the same as for advanced epithelial ovarian cancer. 

The aim of treatment for advanced cancer is usually to shrink the cancer and control it for as long as possible. You might have the following treatments:

Surgery

The aim of surgery is to remove as much of the cancer from the abdomen as possible. This is called cytoreductive or debulking surgery.

The surgery usually includes removing your womb, ovaries, fallopian tubes and the layer of fatty tissue called the omentum.

The surgeon will also remove any other cancer that they can see at the time of surgery. This could include part of the bowel if the cancer has spread there. 

Sometimes PPC can grow so that it blocks the bowel or the urinary system. You might need surgery to unblock these if this happens.

Chemotherapy

Chemotherapy uses anti cancer (cytotoxic) drugs to destroy cancer cells. These drugs work by disrupting the growth of cancer cells. The drugs circulate in the bloodstream around the body.

You may have chemotherapy:

• before surgery to reduce the size of the cancer

• into your abdomen during surgery. This is called hyperthermic intraperitoneal chemotherapy or HIPEC

• after surgery when you have recovered from your operation

• on its own if you are unable to have surgery

Targeted cancer drugs

Some people may have treatment with a targeted cancer drug. This will depend on your situation. You might have a targeted cancer drug:

• with chemotherapy
• on its own after chemotherapy

Radiotherapy

Radiotherapy uses high energy x-rays to kill cancer cells. Radiotherapy isn't often used for PPC. But doctors may use it to shrink tumours and reduce symptoms.

Other treatments

You can have treatment to control symptoms, such as pain and fluid in the abdomen (ascites), even if you are unable to have chemotherapy.

Research into primary peritoneal cancer

Researchers around the world are looking at better ways to diagnose and treat cancers in the ovary, fallopian tube and peritoneum.

Go to Cancer Research UK’s clinical trials database to read about trials for PPC, ovarian and fallopian tube cancer in the UK. The trial summary includes information about who can take part in the trial. You need to talk to your specialist if there are any trials that you think you might be able to take part in.

Coping

Coping with cancer can be difficult, both practically and emotionally. Your healthcare team will help support you.

Being well informed about your condition and its treatment can help you to make decisions and cope with what happens.

Cancer Research UK’s online forum is a place for anyone affected by cancer. You can share experiences, stories and information with other people who know what you are going through.