What is pseudomyxoma peritonei (PMP)?

Pseudomyxoma peritonei (PMP) is a rare cancer that usually starts in the appendix.

PMP is rare and, like many types of cancer, the exact cause is not known. PMP usually begins as a slow-growing cancer in the appendix. Sometimes it may start in another part of the bowel, the bladder or the ovaries.

The digestive system 

The cancer makes a jelly-like liquid called mucin. Eventually the cancer and mucin break out of the appendix (or wherever it is growing). They spread into the space inside the peritoneum (the peritoneal space).

The peritoneum is a layer of tissue that lines the inside of your abdomen. This layer also covers and protects the organs in your abdomen, such as the bowel. The peritoneum makes pockets or gaps around the organs called the peritoneal space.

Side view of female organs 

The cancer cells and mucin build up in the peritoneal space. This will not cause any problems at first and it may be many years before symptoms appear. But eventually there’s enough mucin to put pressure on the bowel and other organs.

PMP usually stays inside the peritoneal space. It rarely spreads to any other part of the body.

Symptoms of pseudomyxoma peritonei

Some of the symptoms of PMP include:

  • gradual increase in waist size
  • hernia (a bulge on the tummy wall)
  • loss of appetite
  • unexplained weight gain
  • tummy (abdominal) or pelvic pain
  • changes in bowel habits.

Diagnosis of pseudomyxoma peritonei

PMP can be difficult to diagnose. You may have some of the symptoms listed above and go for tests. But PMP is often found by accident during treatment for other medical problems. The following tests may be used to diagnose PMP:

  • CT scan

    A CT (computerised tomography) scan uses x-rays to build a three-dimensional (3D) picture of the inside of the body.

  • Ultrasound scan

    An ultrasound scan uses sound waves to build up a picture of the abdomen and organs inside on a computer screen.

  • Drainage of fluid from the abdomen (peritoneal aspiration)

    Your doctor may take a sample of fluid from your tummy to be sent to the laboratory for tests. They will numb the skin over the area first with a local anaesthetic. The doctor will then pass a needle through the skin into the fluid and draw some of the fluid into a syringe.

You may also have a biopsy. This is when the doctor removes a small piece of tissue or cells. A pathologist (doctor who specialises in analysing cells) examines the tissue or cells under a microscope to look for signs of cancer. A biopsy can be taken in different ways:

  • CT or ultrasound-guided biopsy

    A local anaesthetic is used to numb the area. Your doctor will pass a needle through the skin while using an ultrasound or CT scan to check the needle is in the right place. The needle has a tip that can cut out a small piece of tissue.

  • Keyhole surgery (laparoscopy)

    If you have keyhole surgery, you will have either a general anaesthetic or a local anaesthetic and a drug to make you feel relaxed and sleepy. The surgeon makes a small cut in your tummy (abdomen), using a special instrument called a laparoscope. A laparoscope is a thin tube with an eyepiece at one end and a light and camera at the other end. Your doctor can then look around the abdomen and use another instrument to cut out a small piece of tissue.

A surgeon performing laparoscopic surgery

Treatment for pseudomyxoma peritonei

The main treatments for PMP are surgery and chemotherapy. Your treatment plan may depend on how far the cancer has spread and your general health.

Surgery

There are two types of surgery used to treat PMP:

  • cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (HIPEC)
  • debulking surgery.

Cytoreductive surgery with HIPEC

Cytoreductive surgery with HIPEC is a major treatment that aims to remove the cancer and tries to cure PMP. It is also called the Sugarbaker technique (after the surgeon who first developed it). Because this is a major operation, it can have serious complications. It's important to discuss whether it is suitable for you with specialist doctors. After the surgery you’ll stay in a critical care unit for a few days and will be in hospital for around 3 weeks.

During the operation, the surgeon removes as much of the cancer as possible. This usually means removing the gallbladder, parts of the peritoneum and some of the bowel. In women, the surgeon may also remove the womb (uterus) and ovaries.

Once the surgeon has removed all signs of PMP, they put a heated chemotherapy liquid into the peritoneal space (hyperthermic intraperitoneal chemotherapy). Chemotherapy is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells. The aim is to kill any cancer cells that are left behind. After 60 to 90 minutes, the surgeon drains the chemotherapy and finishes the operation.

Some people will have more chemotherapy given into their peritoneal space during the first 5 days following the operation. A nurse or doctor will give this through tubes put into your tummy.

Some people will have a stoma as part of the operation. The stoma is a small opening on your tummy (abdomen) joined to an opening in your bowel. Your bowel motions come through this opening instead of your back passage. You wear a bag over the stoma to collect the bowel motions. The stoma is usually temporary and most people have a small operation to reverse it after about six months.

A stoma and colostomy bag 

There are two specialist centres that do cytoreductive surgery with HIPEC in the UK:

The National Institute for Health and Care Excellence (NICE) is an organisation that currently advises doctors on treatments for all types of illness. It has produced guidelines about this type of surgery and chemotherapy.

Debulking surgery

This is done when it’s not possible to remove all the cancer with cytoreductive surgery. The surgeon removes as much of the PMP as possible to reduce the symptoms of the cancer. They may also remove a part of the peritoneum called the omentum and part of the bowel. In women, they may also remove the womb (uterus) and ovaries.

Unfortunately, this treatment will not take away all the cancer cells and the PMP is likely to grow back. It is possible to have further debulking surgery. However, each operation can become more difficult to do.

Sometimes, a permanent stoma is needed after debulking surgery. This can help prevent the bowel from becoming blocked (obstructed).

Chemotherapy

Chemotherapy may also be given to help to slow the growth of PMP and to reduce symptoms if you can’t have surgery. In this case you have chemotherapy as tablets or as an infusion (drip) into a vein.

Watchful waiting

For some people, the risks of treatment may outweigh the possible benefits, especially as PMP can be slow-growing. In this situation, your doctor may suggest watchful waiting. You will have regular check-ups to monitor the PMP and your symptoms. If the PMP begins to cause you problems, your doctor will discuss starting treatment.

Clinical trials

Cancer research trials are carried out to try to find new and better treatments for cancer. Trials that are carried out on patients are known as clinical trials.

Research into treatments for PMP is ongoing and advances are being made. Sometimes cancer specialists use clinical trials to assess new treatments. You may be asked to take part in a clinical trial. Your doctor must discuss the treatment with you so that you have a full understanding of the trial and what it means to take part.

However, because PMP is rare, there may not always be a relevant trial in progress.

After pseudomyxoma peritonei treatment

Getting support

Your specialist doctor may be able to put you in touch with someone who has PMP, who can share their experience with you. Organisations such as Pseudomyxoma Survivor can also help with this.

You may also want to contact our cancer support specialists free on 0808 808 00 00, 7 days a week, 8am to 8pm, for more information and support.

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