What is 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 of the peritoneum lines the wall of the abdomen.

Cancer that starts in the peritoneum is called primary peritoneal cancer. We have separate information about:

Primary peritoneal cancer is diagnosed and treated in the same way as ovarian cancer. Cancers of the ovary, fallopian tube and of the peritoneum are often grouped together.

Primary peritoneal cancer can affect women, trans men and people assigned female at birth. It can also affect men, trans women and people assigned male at birth but this is very rare. It is diagnosed and treated in the same way as ovarian cancer.

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Types of primary peritoneal cancer

Epithelial

The most common cancer to start in the peritoneum is called epithelial cancer. It starts in the epithelial cells and there are different sub-types.

Serous cancer is the most common. They are usually high-grade which means they can grow more quickly.

Other much less common types are:

  • clear cell
  • endometrioid
  • mucinous.

These are more likely to be diagnosed at an earlier stage than serous cancers.

Borderline tumours

These are also made up of abnormal epithelial cells. But they are not cancer and grow slowly. They may spread to nearby tissue but do not grow in these tissues and do not spread to other parts of the body.

Symptoms of primary peritoneal 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

Causes of primary peritoneal cancer

Doctors do not know what causes cancer to start in the peritoneum. Different things called risk factors may increase the chance of developing it. Having risk factors does not mean someone will get primary peritoneal cancer. The risk factors are thought to be similar to the risk factors for ovarian cancer.

Diagnosis of primary peritoneal 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.

At the hospital

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.

Further tests

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

  • CT scan

    A CT scan takes a series of x-rays, which build up a 3D picture of the inside of the body.

  • Removing fluid from the tummy

    Sometimes swelling in the tummy is caused by a build-up of fluid. This is called ascites. If you have ascites your doctor may want to take a sample of this fluid and test it for cancer cells. The doctor injects some local anaesthetic into the skin on your tummy to numb the area. They gently pass a small needle through the skin and collect some fluid in a syringe. The fluid is sent to the laboratory to be examined.

  • Biopsy

    A biopsy is when doctors remove a small piece of tissue or a sample of cells from an area of the body. The sample is sent to the laboratory and examined under a microscope.

  • Genetic testing

    Your doctor or nurse may talk to you about having a blood test for genetic testing. This is to find out if you have a change (mutation) in the BRCA genes linked to cancer. The results help your doctor decide whether certain targeted therapy drugs could be helpful for you.

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

Staging and grading of primary peritoneal cancer

The stage describes where the cancer started and other areas it may have spread to.

Grading describes how the cancer cells look under the microscope compared with normal cells.

Your doctor does not usually know the exact stage of the cancer until it has been removed with surgery. If you have not had surgery they use your test results to decide the stage.

Knowing the stage and grade helps your doctors plan the best treatment for you.

Treatment for primary peritoneal cancer

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:

  • Surgery

    You usually have surgery to remove all or as much of the cancer as possible. It usually involves removing the womb, ovaries and fallopian tubes.

  • Chemotherapy

    Chemotherapy uses anti-cancer (cytotoxic) drugs to destroy cancer cells. You usually have chemotherapy drugs called carboplatin and paclitaxel. You may have chemotherapy before or after surgery, or both. Sometimes chemotherapy is given on its own as the main treatment if surgery is not possible.

  • Targeted therapies

    Targeted therapy uses drugs to find and attack cancer cells. You may have a type of targeted therapy called a PARP inhibitor drug. Another drug called bevacizumab (Avastin®) may also be used if the cancer has spread further in the pelvis.

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.

Treating primary peritoneal cancer that comes back

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:

  • Hormonal therapy

    Hormonal therapy may slow the growth of the cancer by blocking or reducing oestrogen. It may be used if the cancer comes back and you do not want more chemotherapy or want to delay it. You usually have it for low-grade cancers. The drugs you may have are often the same as those used to treat breast cancer. They include tamoxifen and letrozole.

  • Radiotherapy

    Radiotherapy treats cancer by using high-energy rays to destroy cancer cells. It is not often used to treat primary peritoneal cancer but may be used to control symptoms such as bleeding or pain in the pelvic area. This is called palliative radiotherapy. A type of radiotherapy called stereotactic ablative radiotherapy (SABR) may be used if the cancer is only in one other part of the body, such as a lymph node, the lung or brain.

  • Targeted therapies

    Targeted therapy uses drugs to find and attack cancer cells. You may have a type of targeted therapy called a PARP inhibitor drug. Another drug called bevacizumab (Avastin®) may also be used if the cancer has spread further in the pelvis.

Controlling symptoms

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:

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).

After primary peritoneal cancer treatment

Follow up

After your treatment, you will have regular check-ups. These are usually every few months to start with.

If any symptoms come back or you notice new symptoms, let your specialist doctor or nurse know as soon as possible. You do not have to wait for a follow-up appointment.

You may get anxious between appointments. This is natural. It may help to get support from family, friends or a support organisation. 

CA125 blood tests

CA125 blood tests are sometimes done as part of your follow-up. But this is not always needed. A rising CA125 level may be a sign that the cancer has returned. It may mean you need further tests, such as a CT scan.

Doctors usually advise waiting for cancer symptoms to develop before you have more treatment. This is because: 

  • starting treatment before there are symptoms does not improve treatment results
  • you have shorter periods of time between treatments
  • you have side effects sooner.

But you and your specialist doctor can start to talk about possible options for further treatment.

Your sex life after treatment for primary peritoneal cancer

Cancer and its treatment can cause physical and emotional changes that may affect your sex life. For example, you feel too unwell or tired for sex.  If you have not been through menopause your treatment will usually cause it.

You may also have changes, such as weight gain or hair loss, that affect your body image and self-esteem. If changes to your sex life are difficult to cope with, there is usually help available. Your specialist nurse can give you advice or arrange expert support if needed. 

Well-being and recovery

Even if you already had a healthy lifestyle, you may be more focused on making the most of your health. Changes such as stopping smoking, eating well and keeping active can help your body recover and improve your health and well-being.

We have more information on leading a healthy lifestyle after treatment.

Getting support

Everyone has their own way of dealing with illness and the different emotions they experience. You may find it helpful to talk things over with family and friends or your doctor or nurse.

There are also support organisations that you may find helpful:

  • Eve Appeal
    Eve Appeal offers information and support for anyone affected by gynaecological cancers. Also provides information about cervical screening and for trans, non-binary and intersex people. Call their helpline on 0808 802 0019.
  • Ovacome
    Ovacome offers information and support for anyone affected by ovarian cancer.
  • Target Ovarian Cancer
    Target Ovarian Cancer offers information and support to anyone affected by ovarian cancer. Call their helpline on 020 7923 5475.

Macmillan can offer emotional, practical and financial help and support. If you would like to talk, you can:

About our information

  • References

    Below is a sample of the sources used in our ovarian cancer information. If you would like more information about the sources we use, please contact us at cancerinformationteam@macmillan.org.uk

    Ledermann, Raja, Fotopoulou et al. Newly diagnosed and relapsed epithelial ovarian carcinoma: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology, 2013; Volume 24, Supplement 6. Updated online 2020. Available from www.esmo.org/guidelines (accessed July 2021)

    Management of epithelial ovarian cancer. Scottish Intercollegiate Guidelines Network (SIGN). Nov 2013 revised 2018. Available from www.sign.ac.uk

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Chief Medical Editor, Professor Tim Iveson, Consultant Medical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

The language we use

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

We try to make sure our information is as clear as possible. We use plain English, avoid jargon, explain any medical words, use illustrations to explain text, and make sure important points are highlighted clearly.

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. Our aims are for our information to be as clear and relevant as possible for everyone.

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

Reviewed: 01 September 2021
Reviewed: 01/09/2021
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Next review: 01 September 2024
Next review: 01/09/2024