Primary peritoneal cancer (PPC) is a rare cancer that starts in the peritoneum. The peritoneum is the membrane that lines the inside of the abdomen, clinging to and covering all the organs in the abdomen – for example the intestines, the liver and the stomach.
Primary peritoneal cancer
The peritoneum helps protect the contents of the abdomen. It also produces a lubricating fluid that helps the organs move smoothly inside the abdomen as we move around. A PPC can start in any part of this membrane, but usually in the lower part of the abdomen (pelvis). The peritoneum is made up of cells called epithelial cells. These cells also line the ovaries(and many other areas of the body). Although the lining tissue in the ovaries forms only a small part of the ovaries themselves, this is where most ovarian cancers start. Ovarian cancers commonly spread from the ovaries to the peritoneum. For this reason, primary peritoneal cancer can only be diagnosed in women once ovarian cancer has been excluded. PPC and epithelial ovarian cancer (the most common type of ovarian cancer) behave very similarly, and are treated in the same way.
Another rare type of cancer that can affect the lining of the abdomen is called peritoneal mesothelioma. This mainly occurs in people who have been exposed to asbestos.
Causes of PPC
The causes of PPC are unknown. Like most types of cancer, it is more common in older people. It very rarely occurs in men. A small number of PPCs are associated with an inherited faulty gene linked to breast cancer in the family. People who are worried about cancer because of their family history can be referred to specialist clinics where their risk will be carefully assessed.
Because PPC mainly affects women, this information is written for women.
Signs and symptoms
Most women don’t have any symptoms for a long time. When symptoms do occur, they may include any of the following:
- loss of appetite
- vague indigestion, sickness (nausea) and a bloated feeling
- unexplained weight gain
- swelling in the abdomen – this may be due to a build-up of fluid, known as ascites
- pain in the lower abdomen
- changes in bowel or bladder habits, such as constipation, diarrhea or needing to pass urine more often.
The above symptoms may be caused by a number of conditions other than PPC. However, if you have any symptoms that get worse or last for a few weeks, it’s important to have them checked by your PCP.
How PPC is diagnosed
Usually you begin by seeing your PCP, who will examine you and arrange for you to have any tests that may be necessary, such as ultrasound scans and blood tests. Your PCP may need to refer you to a specialist in conditions of the female reproductive system (a gynecologist) at the hospital for tests, specialist advice and treatment. At the hospital, the gynecologist will ask you about your general health and any previous medical problems. They will then examine you. This will include an internal (vaginal) examination to check for any lumps or swellings. Sometimes, you may also have an examination of your back passage (rectum). You can ask to be seen by a female doctor if you would prefer. Your doctor may arrange for you to have a blood test and chest x-ray to check your general health. You may have a specific blood test to check the levels of a protein called CA125. Levels of this can be higher than normal when a PPC or ovarian cancer is present.
The following tests are commonly used, and you can read about these in more detail in our information about ovarian cancer:
This test uses sound waves to build up a picture of the inside of the abdomen, the liver and the pelvis. It will usually be done in the hospital scanning department.
You will be asked to drink plenty of fluids so that your bladder is full. This will help to provide a clearer picture. Once you are lying comfortably on your back, a gel is spread on to your abdomen. A small device like a microphone, which produces sound waves, is then rubbed over the area. The sound waves are converted into a picture by a computer.
A small device (about the size of a tampon) is put into your vagina. The device produces sound waves, which are then converted into a picture by a computer. Although this type of ultrasound scan may sound uncomfortable, many women find it more comfortable than having a pelvic ultrasound, as it is not necessary to have a full bladder.
CT (computerized tomography) scan
A CT scan takes a series of x-rays that build up a three-dimensional picture of the inside of the body. The scan is painless and takes 10-30 minutes. CT scans use a small amount of radiation, which is very unlikely to harm you and won’t harm anyone you come into contact with. You will be asked not to eat or drink for at least four hours before the scan. You may be given a drink or injection of a dye, which allows particular areas to be seen more clearly. For a few minutes, this may make you feel hot all over. If you’re allergic to iodine or have asthma, you could have a more serious reaction to the injection, so it’s important to let the hospital doctor know beforehand. Once you are lying in a comfortable position, the scan will be taken. You will probably be able to go home as soon as the scan is over.
MRI (magnetic resonance imaging) scan
This test is similar to a CT scan, but uses magnetism instead of x-rays to build up a detailed picture of areas of your body. Before the scan you may be asked to complete and sign a checklist. This is to make sure that it’s safe for you to have an MRI scan. Before having the scan, you’ll be asked to remove any metal belongings, including jewelry. Some people are given an injection of dye into a vein in the arm. This is called a contrast medium and can help the images from the scan to show up more clearly. During the test you will be asked to lie very still on a couch inside a long cylinder (tube) for about 30 minutes. It’s painless but can be slightly uncomfortable, and some people feel a bit claustrophobic during the scan. It’s also noisy, but you’ll be given earplugs or headphones
Abdominal fluid aspiration
Sometimes with PPC, there is a build-up of fluid in the abdomen (known as ascites). If this happens, a sample of the fluid can be taken to check for any cancer cells. The doctor will use a local anesthetic to numb the area before passing a small needle through the skin. Some fluid is drawn into a syringe and examined under a microscope. Sometimes the sample of fluid is taken while you’re having an ultrasound scan. The scan helps guide the doctor to the fluid.
This is a small operation that allows the doctor to look at the ovaries and the surrounding area. It is done under a general anesthetic and will require a short stay in hospital. While you’re under anesthetic, the doctor makes a small cut (about 1cm long) in the skin and muscle of the lower abdomen and carefully inserts a thin mini-telescope (laparoscope). Looking through the laparoscope, the doctor can look at the ovaries and take a small sample of tissue (biopsy) to examine under a microscope. During the operation, carbon dioxide (CO2) gas is passed into the abdominal cavity and this can cause uncomfortable wind and/or shoulder pains for several days afterwards. The pain is often eased by walking about or by taking sips of peppermint water. After a laparoscopy, you will have one or two stitches in your lower abdomen. You should be able to get up as soon as the effects of the anesthetic have worn off.
Sometimes it is necessary for a full operation (laparotomy) to be carried out in order to make a definite diagnosis of primary peritoneal cancer. A larger cut is made in the skin and muscle of the abdomen to allow the surgeon to inspect all the organs in the abdomen.
Staging of PPC
The stage of a cancer is a term used to describe its size and whether or not it has spread beyond its original site. Knowing the extent of the cancer helps the doctors decide on the most appropriate treatment for you. Because ovarian and primary peritoneal cancers are so alike, the same staging system is used. PPCs are either stage 3 or stage 4.
Cancer is present in the lining of the abdomen (peritoneum).
The cancer has spread to places such as the liver, lungs or distant lymph nodes (for example in the neck).
Treatment for PPC
A number of different types of treatment are used to treat PPC.
You may be offered surgery to remove as much of the cancer as possible. This usually involves removing the womb (uterus), ovaries, the sheet of fatty tissue inside the abdomen (omentum), and as much of the tumor elsewhere as possible.
Chemotherapy is the use of anti-cancer (cytotoxic) drugs to destroy cancer cells. They work by destroying the growth and division of cancer cells. Chemotherapy is often given after surgery if it wasn’t possible to remove all of the tumor, or if there is a risk that some cancer may have been left behind. If the surgeon feels that the cancer may be difficult to remove, chemotherapy may be given first and surgery carried out afterwards. This is to make the tumor smaller and easier to remove.
Radiotherapy treats cancer by using high-energy rays to destroy cancer cells, while doing as little harm as possible to normal cells. Radiotherapy is occasionally used to treat individual areas of PPC if it comes back after surgery and chemotherapy.
Clinical trials for PPC
Research into new ways of treating PPC is ongoing. Doctors are continually looking for improved ways of treating the disease and they do this by using clinical trials. Many hospitals now take part in these trials. Before any trial is allowed to take place it must have been approved by an ethics committee, which checks that the trial is in the interest of patients. 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 involves. You may decide not to take part, or to withdraw from a trial, at any stage. If this is the case you will still receive the best standard treatment available.