Pseudomyxoma Peritonei
What is Pseudomyxoma Peritonei?
Pseudomyxoma Peritonei is a rare disease of the abdominal (peritoneal) cavity. The majority of cases result from mucin (jelly) secreting abnormal cells forming a tumour in the appendix. More rarely, the condition arises in other parts of the bowel or in the ovary in females and in rare cases, in other organs such as the urinary bladder.
The disease is due to the presence of a large amount of mucinous fluid which is the consistency of jelly in the abdominal cavity and is often commonly referred to as ‘Jelly Belly’. The mucin is produced by abnormal cells that have spread and grown on the peritoneum which lines the abdominal cavity.
Pseudomyxoma Peritonei is often referred to as being a ‘borderline malignant’ condition. The characteristics of a malignancy are that the disease spreads via the lymphatic system to the lymph nodes and by the blood vessels (vascular spread), thus reaching the liver, lungs, brain and other organs. Pseudomyxoma Peritonei spreads only within the abdominal cavity in the majority of cases and does not spread via the lymphatics or the blood stream.
However Pseudomyxoma Peritonei is not completely benign as it continues to grow and eventually takes over the peritoneal cavity. Patients feel bloated and the abdomen get very bloated and distended.
If untreated it will result in compression of the abdominal organs making normal nutrition no longer possible resulting in severe malnutrition.
Treatment and Surgical options
Pseudomyxoma Peritonei most commonly arises from appendix tumours. Depending on the type of appendix tumour the way the patient has presented and patient individual factors the following options may be considered.
1. Watch and wait
This will involve regular scans to monitor the distribution and progression of the disease and decide to intervene if appropriate or the patient becomes more symptomatic. This option is usually used for patients with minimal disease, if surgical treatment has been deemed to be too high risk or if the patient chooses to not have surgery.
2. Chemotherapy
The commonly used forms of chemotherapy (oral or intravenous) have very little role in the treatment of Pseudomyxoma Peritonei. This is due to the fact that the disease is of borderline malignancy and has a very poor blood supply so chemotherapy does not gain access to the cells. In addition low grade tumour cells usually divide slowly and thus chemotherapy drugs do not work. All chemotherapy treatment relies on a balance between the benefits and risks. For a low grade tumour the risks of treatment far outweigh the benefits therefore the majority of oncologists (chemotherapy specialists) consider that chemotherapy has no place in the management of early Pseudomyxoma Peritonei. However intestinal type chemotherapy sometimes has beneficial effects if the tumour is a mucinous adenocarcinoma.
Radiotherapy does not have a relevant place in the management of Pseudomyxoma Peritonei, as it is impossible to apply radiotherapy to a large area without causing damage to the other abdominal organs and the bowel.
Surgery (broadly includes two types)
Cytoreductive surgery (CRS) combined with Hyperthermic Intraperitoneal Chemotherapy (HIPEC)
Complete cytoreductive surgery – complete removal of all visible tumour – is a technique developed and popularised by Professor Paul Sugarbaker at the Washington Cancer Centre. It is combined with Hyperthermic Intraperitoneal Chemotherapy (HIPEC) when a chemotherapy solution is poured into the abdominal cavity during the operation.
The average operating time for CRS and HIPEC is ten hours but this is dependent on the distribution of the disease within the abdomen.
The operation aims to remove all abnormal tissue and comprises of a number of different procedures, namely:
- Right and left parietal peritonectomy (lining on each side of the abdomen)
- Pelvic peritonectomy, which sometimes includes the rectum by anterior resection and in the female includes removal of the ovaries and uterus
- Stripping of the peritoneum from the left hemidiaphragm
- Stripping of the peritoneum from the right hemidiaphragm
- Stripping of disease from the surface of the liver
- Appendicectomy
- Right hemicolectomy
- Greater omentectomy
- Splenectomy
- Cholecystectomy
- Lesser omentectomy
An important factor at surgery is the involvement of the small bowel. In general the small bowel is not grossly involved due to small bowel peristalsis (normal movement of the bowel) being relatively protective against tumour implantation and growth. One of the ways of determining involvement of the small bowel prior to surgery is a CT scan with oral contrast to outline the small bowel. In selected patients a small operation called a staging laparoscopy where a camera is inserted in the abdomen under general anaesthetic (laparoscopy) is done to look to assess the small bowel and abdominal cavity prior to CRS and HIPEC.
On the pre operative CT scan sometimes it is possible to see tumour displacing the small bowel and involving its surface and mesentery which is usually a poor prognostic factor. Most cases have some degree of small bowel involvement but it is usually possible to deal with limited small bowel disease at the time of CRS HIPEC.
If all disease can be removed heated chemotherapy (HIPEC) usually Mitomycin C is given directly into the peritoneal cavity at the time of operation at a temperature of approximately 42-43°C. Intra peritoneal 5FU is given in selected cases for four days post-operatively.
In about 80% of cases complete cytoreduction (removal of all abnormal disease) can be achieved. In the remaining cases a major tumour debulking is performed. Please see below.
Major Tumour Debulking
This surgical approach is used if complete cytoreduction is not possible and aims to remove as much of the tumour as possible. It usually includes removal of the uterus and ovaries in the female and often all the large bowel (colon), the omentum in men and women leaving a permanent bag (stoma). Disease progression/recurrence is almost inevitable due to residual disease around the peritoneal cavity. Repeat debulking surgery may be possible, but each attempt becomes more difficult and dangerous. This is because the small bowel becomes increasingly involved due to disease and adhesions following previous surgery, eventually surgery is impossible and is fraught with severe complications such as small bowel fistulae and intestinal failure.
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Basingstoke Colorectal & Peritoneal
The Hampshire Clinic
Basing Road
Basingstoke RG24 7AL
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01256 354747