Peritoneal cancer is a rare form of cancer that affects the membrane that surrounds the organs of the abdomen. It mostly affects women and often goes undetected until it is quite advanced. Treatment is available and the type of therapy and its success depends on how serious the cancer is and how far it has spread. Peritoneal cancer that seems to have been beaten can come back quite quickly and regular checkups are required for several years afterwards.
This article on peritoneal cancer treatment is by Kathryn Senior, a freelance journalist who writes health, medical, biological, and pharmaceutical articles for national and international journals, newsletters and web sites.
What is peritoneal cancer?
The peritoneum is the membrane of epithelial cells that surrounds all of the important organs in the abdomen. This membrane helps protect the intestines, liver, kidneys and reproductive organs, keeping them in place as the body moves around. Tumours within this membrane result in peritoneal cancer.
There are several different types of peritoneal cancer and all are quite rare. Cancer that arises in the peritoneum is usually described as primary peritoneal cancer. Its exact cause is unknown but it is more common with increasing age and is most often seen in women. A second type, peritoneal mesothelioma, is exceptionally rare, affecting only 40 people per million in the UK. This form of peritoneal cancer is almost always associated with asbestos exposure.
As with many cancers of the abdomen symptoms often do not appear until peritoneal cancer reaches an advanced stage. When symptoms do occur, they are very non-specific. All are much more likely to have another, far less serious cause:
- Lack of appetite
- Weight gain
- Nausea and bloating
- Swelling and pain in the abdomen
- Constipation or diarrhoea
How is it diagnosed?
There are many methods of investigating a suspected case of peritoneal cancer:
- Internal vaginal and rectal examination
- Blood tests to check protein levels (specifically CA125)
- Tests on fluid that builds up in the abdomen
One or more scans may also be carried out to establish the extent and location of the peritoneal tumour, including pelvic or vaginal ultrasound scans, CT scans and MRI scans. A surgeon may operate to visualise the tumour and to take a sample for biopsy. This may be done via keyhole techniques or using open abdominal surgery.
Peritoneal cancer is often due to a secondary tumour that has spread from a primary ovarian cancer. Ovarian cancer is therefore suspected in all cases of peritoneal cancer and a definite diagnosis of primary peritoneal cancer is only made when ovarian cancer has been ruled out.
Grading peritoneal cancer
Like ovarian cancer, peritoneal cancer often develops unnoticed, which makes an early diagnosis difficult. Peritoneal cancers are usually graded as Stage 3; the cancer is well-developed but it is still confined to the peritoneal membrane. If the grading is Stage 4, this means that metastases, or secondary cancers, have developed beyond the peritoneum, often in the liver or lungs.
Treating stage 3 cancer
Treatment for Stage 3 peritoneal cancer usually involves an aggressive combination of surgery, chemotherapy and radiotherapy. All three techniques are used in an attempt to remove the cancer and prevent its recurrence. Surgery usually involves a total hysterectomy; the womb and both ovaries are removed. As much of the actual cancer is taken away as is physically possible and the fatty lining of the abdomen, the omentum, may also be removed.
Chemotherapy may be provided before surgery, to reduce the mass of the tumour, or following surgery, to destroy any cancerous cells left behind. Combinations of 5-fluorouracil, doxorubicin and cisplatin may be used. In some cases, chemotherapy may be offered both before and after surgery, or as an alternative to surgery where an operation is considered too radical for the health of the person involved. Chemotherapy is administered either weekly or fortnightly as an outpatient and can be highly effective in reducing tumour size. Unfortunately, however, these aggressive drugs do come with many unpleasant side effects, including nausea, lethargy and headaches and anti-nausea drugs are also usually necessary.
Radiotherapy is not generally used as a primary treatment for peritoneal cancer, although it is occasionally called upon to tackle stubborn areas of cancer that return following surgery and which do not respond to chemotherapy.
Treating stage 4 cancer
In Stage 4 peritoneal cancer, the treatment is generally more palliative, with the focus on reducing the symptoms and making the patient comfortable, rather than fighting the disease. Pain relief is paramount in palliative care, often involving high strength morphine-based painkillers. Advanced peritoneal cancer produces large amounts of fluid, distending the abdomen and causing discomfort. This can be drained away using a technique known as abdominal paracentesis.
Peritoneal cancer is so rare that doctors are uncertain how it will respond to the new treatments that are being developed for other cancers. It is therefore likely that anyone with peritoneal cancer will be approached to participate in a clinical trial. As well as looking at how the cancer responds to therapy, such trials may also help researchers to identify biomarkers so that they can develop a blood test to diagnose peritoneal cancer at a much earlier stage.