Primary peritoneal cancer

The peritoneum is a layer of tissue in the tummy (abdomen). The inner layer covers the surface of all the organs in the abdomen, such as the stomach, liver and bowel. The outer layer lines the wall of the abdomen.

When cancer starts in the peritoneum, this is called primary peritoneal cancer. We have separate information about:

• peritoneal mesothelioma, a different type of cancer that starts in the peritoneum
• pseudomyxoma peritonei (PMP), a rare cancer that often affects the peritoneum.

Primary peritoneal cancer is rare. It can affect men as well as women, although this is very rare. It is diagnosed and treated in the same way as ovarian cancer.

Primary peritoneal cancer usually causes symptoms that are similar to to common non-cancerous conditions. This can make it difficult to diagnose early.

Symptoms can include a long-lasting bloated or swollen tummy,  loss of appetite or peeing more often than usual. They are the same as the symptoms of ovarian cancer. 

Your GP asks about your symptoms and does an internal (vaginal) examination to check for any lumps or swelling. They usually arrange the following tests: 

• a CA125 blood test to check for raised levels of this protein, which may be higher in ovarian cancer
• ultrasound scan to check the organs in the pelvis and tummy area.

If the ultrasound shows any abnormal areas, your GP arranges for you to see a specialist doctor (a gynaecological cancer specialist). You should be seen within 2 weeks.

If a GP finds a lump in your pelvis or fluid in your tummy (ascites), they refer you to a specialist straight away.

Sometimes primary peritoneal cancer is diagnosed after being admitted to hospital with a symptom that is making you unwell.

Your specialist doctor will usually ask about: 

• your general health
• any previous health problems
• any history of cancer in your family.

They do another internal examination. If you have not had a CA125 blood test or an ultrasound scan the doctor will arrange these tests for you.

Risk of malignancy index (RMI)

Your doctor may use your test results to check your Risk of Malignancy Index (RMI) score. This system checks how likely it is your symptoms are caused by cancer.

RMI looks at:

• whether you have gone through menopause
• the levels of CA125 in your blood
• the results of your ultrasound.

Your specialist doctor arranges further tests. These help to diagnose the cancer and to plan your treatment. You may have:

Waiting for test results can be a difficult time. We have more information that may help.

A team of specialists will meet to discuss the best possible treatment for you. This is called a multidisciplinary team (MDT).

Your cancer doctor and specialist nurse will explain the different treatments and their side effects. They will also talk to you about the things you should consider when making treatment decisions.

Primary peritoneal tube cancer is treated in the same way as ovarian cancer. The main treatments are:

You may have some treatments as part of a clinical trial.

We have more information about how different treatments are used to treat primary peritoneal cancer.

It can be very hard to hear that the cancer has come back again. You may feel shocked and find it difficult to think of having treatment again. Your doctor and specialist nurse are there to help and support you. They will explain the best treatment options for you. The aim is to control the cancer for as long as possible. Your treatment will depend on:

• the treatment you had before
• how long it kept the cancer away
• if you had any difficult side effects from previous treatments.

You usually have more chemotherapy and a targeted therapy drug. Sometimes further surgery is possible. You may have different treatments over several years to control the cancer. Your doctor may also talk to you about having newer treatments in a clinical trial.

Other cancer treatments are occasionally used:

Treatments for the cancer often improve any symptoms you have. If the cancer is more advanced you may see a specialist doctor or nurse for expert help in managing symptoms. This is called supportive or palliative care. We have more information about coping with advanced cancer.

Sometimes advanced ovarian cancer causes symptoms because of a build-up of fluid:

• in the tummy (called ascites)
• in the lung (called a pleural effusion) if the cancer has spread to the lung.

Your doctor will arrange to have the fluid drained away to make you feel more comfortable and less breathless.

Blocked bowel (bowel obstruction)

If the cancer is growing close to the bowel, it may put pressure on the bowel. This can cause a blockage so the bowel contents cannot easily pass through. Or it may happen because surgery to the abdomen causes tissues to stick together (called adhesions).

Symptoms can include:

• tummy pain
• bloating
• feeling sick
• vomiting large amounts
• constipation
• diarrhoea.

There are different ways it can be managed. Your doctor and nurse will talk this over with you. Treating the cancer may improve a bowel obstruction. But sometimes you may need surgery to remove the blocked section of bowel.

A blocked bowel can also be managed by having fluids through a drip for a time. Sometimes your doctor may suggest having nutrients through a tube, either into the stomach (enteral nutrition) or into a vein (parenteral nutrition).

We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

• use plain English
• explain medical words
• use short sentences
• use illustrations to explain text
• structure the information clearly
• make sure important points are clear.

We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

You can read more about how we produce our information here.