Primary peritoneal carcinoma
This page tells you about primary peritoneal cancer. There is information about
The peritoneum is a layer of thin tissue that lines the abdomen and covers all of the organs within it, such as the bowel and the liver. The peritoneum protects the organs and acts as a barrier to infection. It has 2 layers. One layer lines the abdominal wall and is called the parietal layer. The other layer covers the organs and is called the visceral layer.
There is a small amount of fluid between the two layers, which separates them and allows them to slide over each other. This fluid allows us to move around without causing any friction on the layers.
Primary peritoneal cancer (PPC) is a rare cancer of the peritoneum. It is very similar to the most common type of ovarian cancer called epithelial cancer. This is because the lining of the abdomen and the surface of the ovary come from the same tissue when we develop from embryos in the womb. Doctors now think that most high grade serous cancers actually start in the far end of the fallopian tube rather than the surface of the ovary or peritoneum.
Doctors stage cancers to help them decide the treatment that people need. Staging tells them about how big a cancer is and where it is in the body. The staging system for PPCs is the same as for ovarian cancers but there is no early stage. PPC is always either stage 3 or stage 4. This is an advanced cancer. PPC does sometimes affect the ovaries but to be a PPC it must only be on the surface of the ovary.
PPC is a cancer that mainly affects women. There are no exact numbers for how many people get it in the UK. Research suggests that between 7 and 15 out of 100 women (7 to 15%) who have advanced ovarian cancer will actually have PPC. It is very rare in men. Most people are over the age of 60 when they are diagnosed.
The causes of PPC are unknown. Most cancers are caused by a number of different factors working together. Research suggests that a very small number of PPCs may be linked to an inherited faulty gene. This is the same gene that increases the risk of ovarian cancer and breast cancer. You can find out more about this gene, called the BRCA gene, on the ovarian cancer risks and causes page.
Symptoms for primary peritoneal cancer can be very unclear and difficult to spot, especially when it is in its early stages. Many of the symptoms are more likely to be caused by other medical conditions.
The symptoms of PPC include
- A swollen abdomen due to a build up of fluid (ascites)
- Abdominal pain
- Constipation or diarrhoea
- Feeling or being sick
- Feeling bloated
- Loss of appetite
The tests you may have include
Most people start by seeing their GP. They may want to examine your abdomen. They will press gently on the outside of your abdomen to feel for any lumps, or tender areas.
Your doctor may also want to examine you internally. This is to see if your abdomen, including your womb and ovaries, feels normal. Your doctor will ask you to lie on your back on the couch with your feet drawn up and your knees apart. They will then put one or two gloved fingers into your vagina. At the same time they press down on your abdomen with the other hand. If any part of the abdomen is enlarged, or if a lump of any kind is there, your doctor may be able to feel it.
You might need to have an ultrasound scan to help make a diagnosis. An ultrasound uses sound waves to build up a picture of a part of the body. You might have an abdominal ultrasound or a transvaginal ultrasound.
Primary peritoneal cancers often produce a protein called CA125 that shows up in a blood test. Doctors call this a tumour marker. A raised level of CA125 can be a sign of either PPC or ovarian cancer or fallopian tube cancer. But it doesn’t necessarily mean that you have cancer because it can be raised for other reasons, such as
• Pelvic inflammatory disease
The treatment you have depends on a number of things including
- The size of your cancer
- Where the cancer is in the abdomen
- Your general health
The treatment for PPC is the same as for advanced epithelial ovarian cancer. Because PPC is usually at an advanced stage when it is diagnosed it can be difficult to treat. The aim of treatment for advanced cancer is usually to shrink the cancer and control it for as long as possible.
The main treatments are
The aim of surgery is to remove as much of the cancer from the abdomen as possible before chemotherapy. This is called debulking surgery. Chemotherapy tends to work better when there are only small tumours inside the abdomen. The surgery usually includes removing your womb, ovaries, fallopian tubes and the layer of fatty tissue called the omentum. The surgeon will also remove any other cancer that they can see at the time of surgery. This may include part of the bowel if the cancer has spread there.
The preparation for the operation, and your recovery afterwards, is the same as for an abdominal hysterectomy. You can read about hysterectomy in the surgery for ovarian cancer section.
Sometimes PPC can grow so that it blocks the bowel or the urinary system. You may need surgery to unblock these if this happens. There is information about this on the page about treatment for advanced ovarian cancer.
Chemotherapy uses anti cancer (cytotoxic) drugs to destroy cancer cells. These drugs work by disrupting the growth of cancer cells. The drugs circulate in the bloodstream around the body. You may have chemotherapy
- Before surgery to reduce the size of the cancer
- After surgery when you have recovered
- On its own if you are unable to have surgery
The most common chemotherapy drugs used to treat PPC are a combination of carboplatin and paclitaxel (Taxol). You can read more about the chemotherapy drugs doctors use in the treating ovarian cancer section.
Radiotherapy uses high energy waves to kill cancer cells. Radiotherapy is not often used for PPCs. But doctors may use it to shrink tumours and reduce symptoms. There is information about having radiotherapy in the section about radiotherapy for ovarian cancer. And there is general information about radiotherapy in the main radiotherapy section.
If you are unable to have chemotherapy, you can still have treatment to control any symptoms, such as pain, weight loss, and fluid in the abdomen. Fluid can build up between the two layers of the peritoneum. This fluid build up is called ascites. It can be very uncomfortable and heavy. Your doctor can drain the fluid off using a procedure called abdominal paracentesis or an ascitic tap. The diagram below shows this.
Doctors and researchers are looking into a number of treatments for PPC. In the ICON 8 trial, they are looking at whether giving weekly chemotherapy at a lower dose works as well as chemotherapy every 3 weeks at a higher dose.
One trial is looking at adding a new drug called saracatinib (also known as AZD 0530) to paclitaxel. Saracatinib is a type of biological therapy called a cancer growth blocker. It stops cells sending growth messages and so stops the cancer cells growing, dividing and surviving.
Researchers are looking at giving chemotherapy into the abdomen (intraperitoneal chemotherapy) for PPC. The PETROC trial is testing 3 different types of chemotherapy for PPC or ovarian cancer. It wants to find out how well intraperitoneal chemotherapy works.
The CHORUS trial is comparing surgery before and during chemotherapy for PPC and ovarian cancer. The women taking part have either surgery followed by chemotherapy, or they have some chemotherapy followed by surgery (neo adjuvant chemotherapy) and then more chemotherapy. The aim of the trial is to find out whether the timing of chemotherapy and surgery affects how well treatment works.
You can find information about research trials looking at treatments for PPC on our clinical trials database. Some trials for advanced ovarian cancer are also open to people with PPC. Type ‘primary peritoneal cancer’ into the search box. Or choose ‘ovarian and primary peritoneal cancer’ from the dropdown list of cancer types. Tick the boxes for closed trials and results if you want to include all the trials.
Coping with a rare condition can be difficult, both practically and emotionally. As PPC is often diagnosed at an advanced stage this can be very hard to cope with. Being well informed about your condition and its treatment can help you to make decisions and cope with what happens.
You can read more about this in the coping with cancer section.
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