Pseudomyxoma Peritonei FAQ

frequently asked questions about PMP

We’ve created a list of questions commonly asked by those anyone looking for summary information about pseudomyxoma peritonei (PMP), be that patients, caregivers or the media. This is just a summary, for further information, please see our PMP information page and the rest of our website. If you don’t find an answer to your question here or around the site, feel free to contact us.

You may also find it helpful to read our Glossary of Terms.

So what is PMP?

PMP is an abbreviation for pseudomyxoma peritonei. PMP, a peritoneal surface malignancy, is a rare condition defined as the presence of mucin and mucinous tumours in the abdominal cavity. There’s a number of origins for PMP with the most common source is being a tumour of the appendix (appendix cancer). Classification of PMP is based upon several factors including the malignancy of the original tumour and that of the tumours in the abdominal cavity. The World Health Organization (WHO) classifies PMP as low grade or high grade. It’s also recognised that there is a hybrid with intermediate features.

How should I pronounce pseudomyxoma peritonei?

SOO-doh-mix-OH-muh PAYR-ih-TOH-nee-EYE

Just how rare is PMP?

Pseudomyxoma peritonei is an extremely rare disease. Estimates vary and it’s often quoted as the ‘1 in 1 million disease’. However, it is now thought that PMP is diagnosed in between 3-4 people per million each year¹. Possibly due to prior misdiagnosis or misclassification, some treatment centres are reporting that incidence may be as high as 10 per million per year.

PMP is identified by Eurordis as a rare or “orphan” disease (one which affects less than 1 in 2000 people).

The incidence of PMP is so low that most GPs will never see a case in their working life which makes it much more difficult for symptoms to be picked up. Most pathologists see few cases and may identify the cells incorrectly resulting in an incorrect diagnosis and consequently inappropriate or no treatment.

What are the causes of PMP?

There’s no known cause of PMP although there are a number of theories about the origins of PMP. It is generally accepted that an appendix tumour is the most common source of the PMP. The appendix is part of the bowel and so it is thought that the cause of PMP maybe similar to those for colon cancer although the way the tumours behave can be quite difference.

More rarely, PMP has also been known to be caused by tumours that originate in the ovary, bladder, stomach, colon, pancreas and other abdominal organs.

Who does PMP affect?

Most studies show that PMP affects men and women almost equally. The age at diagnosis ranges from late teens onwards with most patients diagnosed in their 40s or in  their 50s. There doesn’t appear to be a genetic factor for PMP.

What are the symptoms of PMP?

Pseudomyxoma peritonei symptoms usually take a while to appear; some patients don’t show any symptoms for several years. Symptoms of PMP vary widely between patients so it’s hard to say what to look for. As the disease progresses, many patients report:

  • Abdominal swelling or an increase in abdominal girth
  • Changes in bowel habit
  • Loss of appetite
  • Pelvic or abdominal pain
  • General fatigue
  • Bowel irritation

These symptoms can be caused by lots of medical conditions other than PMP. However, due to the nature of this cancer, it’s vital to rule out PMP as a cause.

How’s PMP diagnosed?

Pseudomyxoma peritonei is usually found during an unrelated procedure such as during an operation for something else when the mucin and the tumours are seen in the abdominal cavity or during tests for something else when the traits of PMP are seen on a scan or blood tests highlight further investigation is needed. Diagnosis and monitoring of PMP is generally by:


  • CT scan of the chest, abdomen and pelvis
  • Exploratory laparoscopy
  • Blood tests (tumour markers) CEA, CA-125, and CA 19-9 are typical although these aren’t an indicator for all patients

When tumours and mucin are found during another operation, diagnosis is given after pathology tests. Because of the rarity of PMP, many pathologists may not have seen cells like this before and this makes it harder to diagnose.

What’s the treatment for PMP?

The “standard of care” for the treatment of pseudomyxoma peritonei by a PMP specialist is generally a combination of specialized cytroreductive surgery (CRS) to attempt to remove all of the tumours and affected tissue, followed by heated intraperitoneal chemotherapy (HIPEC) in the abdominal cavity.
Some specialists recommend early post-operative intraperitoneal chemotherapy (EPIC) for approximately three to five days following CRS+HIPEC surgery. In many cases, a specialist may also recommend preventive post-operative systemic chemotherapy.

CRS and HIPEC sounds complicated, what is it?

Cytoreductive surgery (CRS) for pseudomyxoma peritonei is a complex operation with the aim of removing all visible tumours, affected tissue and entire organs. The National Institute for Health and Care Excellence (NICE) guidelines recommends the Sugarbaker technique and defines the operation as radical.

The Sugarbaker technique was developed by Dr Paul Sugarbaker at the Washington Cancer Institute. It involves complete surgical tumour removal (complete cytoreduction) combined with intraoperative heated chemotherapy, followed by postoperative intraperitoneal chemotherapy. The operation takes about 10 hours to complete and includes:

  • removal of the right hemicolon, spleen, gall bladder, greater omentum and lesser omentum
  • stripping of the peritoneum from the pelvis and diaphragm
  • stripping of tumour from the surface of the liver
  • removal of the uterus and ovaries in women
  • removal of the rectum in some cases

The operation can last anywhere from six to over 15 hours. Some patients have a colostomy or an ileostomy as a result of the surgery. The ostomy may be temporary or permanent, depending on individual circumstances. A temporary ostomy allows the bowel to heal after resection.

After the surgery, before the patient is closed up, a perfusion of heated intraperitoneal chemotherapy (HIPEC). A chemotherapy drug (often Mitomycin-C) is typically used to kill cancer cells that are not visible to the human eye. HIPEC may add another 90-120 minutes to the surgical procedure. Some specialists, though not all, continue intra-abdominal chemotherapy for a period of between three and five days after the operation. Cytoreductive surgery and HIPEC (CRS & HIPEC) is a major procedure with a long recovery time. Even without complications, patients typically stay in hospital for at least two weeks.

It can take up to a year to physically recover from the operation although many patients make a quicker recovery with some returning to work within eight weeks or so.

Why can’t you just have your appendix out?

PMP is a condition where the tumour has erupted into the abdominal cavity spreading tumour cells and mucin. Just having your appendix out wouldn’t remove these cells or mucin and PMP would continue to develop.

Why should PMP patients be treated by a specialist?

Pseudomyxoma peritonei is a rare and complex condition which most doctors will not come across in their working career. Studies have shown that the treatment of PMP has a long learning curve – 140 operations or more and so it is highly recommend that PMP patients seek out a specialist who deals with PMP on a regular basis.

Is there a cure for PMP?

Pseudomyxoma peritonei is generally considered treatable but not curable for most patients. As the experience of specialists develops, there are a growing number of PMP patients who are experiencing many years with no evidence of disease (NED) following cytoreductive surgery and HIPEC. Please bear in mind when looking at statistics that most centres track patients for up to ten years only.

What’s MOAS?

MOAS is an abbreviation for the term the “Mother of All Surgeries” and refers to CRS and HIPEC.  The phrase was coined by the wife of a patient on her blog about their experiences with pseudomyxoma peritonei. The expression stuck and has become standard language in the PMP community.

How can I help support patients?

Patients and their caregivers benefit from emotional and practical support. We can help with that but we rely on donations to support our work. You can help by making a one-off or recurring donation.


(1) Estimating the incidence and prevalence of pseudomyxoma peritonei in Europe

¹Patrick-Brown, T.D.J.H., Carr, N.J., Swanson, D.M. et al. Estimating the Prevalence of Pseudomyxoma Peritonei in Europe Using a Novel Statistical Method. Ann Surg Oncol (2020). Accessed June 2020.

Author: A Brook

Updated: August 2020