Risk factors and causes of ovarian cancer
Each year, about 6600 women in the UK are diagnosed with ovarian cancer. The causes are not yet completely understood. The risk of developing ovarian cancer is very low in young women and increases as women get older. Over eight out of ten (85%) ovarian cancers occur in women over the age of 50. Most ovarian cancers occur in women who have had their menopause.
Some factors are known to affect a woman's chance of developing ovarian cancer – they may increase the risk or decrease it. These are described below.
Women who have not had children are slightly more likely to develop ovarian cancer than women who have, although the risk is still very low. Having two or more children may provide more protection than just one.
Breast feeding your children may slightly decrease your risk.
Starting your periods early or having a late menopause slightly increases your risk of ovarian cancer.
Women who take the contraceptive pill are less likely to develop ovarian cancer.
Using oestrogen-only hormone replacement therapy (HRT) can slightly increase the risk. When HRT is stopped the risk of ovarian cancer gradually reduces to the same level as women who haven't taken HRT.
Infertility and fertility treatments
Research has shown that infertility treatment may slightly increase the risk of developing ovarian cancer. However, other research doesn't support this.
Having endometriosis may increase your risk of ovarian cancer.
Being overweight may increase your risk of developing ovarian cancer. Eating a diet high in animal fats and low in fresh fruit and vegetables may increase your risk.
About 5–10 in 100 (5–10%) ovarian cancers are caused by an inherited faulty gene in the family.
Women who have had breast cancer have an increased risk of ovarian cancer. This is because breast and ovarian cancer can be caused by the same faulty genes.
If any of the following are present in one side of your family, it is possible that there may be an inherited faulty gene:
Ovarian cancer in at least two close relatives (mother, sisters or daughters). One close relative with ovarian cancer and one close relative with breast cancer diagnosed when they were under the age of 50 (or both cancers in the same person).
Ovarian cancer in one close relative and breast cancer in two family members diagnosed when they were under the age of 60.
Three close relatives with colon (bowel) or womb (endometrial) cancer, and one relative with ovarian cancer.
Having one elderly relative with ovarian cancer doesn't necessarily increase your risk of ovarian cancer.
Women who are worried that they may have an increased risk of developing ovarian cancer, because of cancer in their family, can be referred to a genetic counselling clinic.
If two or more of your close relatives have had ovarian cancer you may want to consider having testing (screening) for ovarian cancer. However, it is not yet known how effective screening is at detecting ovarian cancer (screening).
Screening for ovarian cancer
Research trials are being carried out to see whether ovarian cancers can be detected early so that they can be treated more effectively. The trials are testing women who have no symptoms of ovarian cancer, to see if testing can detect a cancer at an early stage. This is known as screening. Currently it is not known whether screening can help to detect ovarian cancers at an earlier stage, so there is no national screening programme for ovarian cancer in the UK.
Women who may have an increased risk of ovarian cancer can ask their GP to refer them to take part in an ovarian cancer screening research trial.
A recent research study is looking at the benefits of screening postmenopausal women with either a blood test for a protein called CA125 or a vaginal ultrasound (see diagnosis). The aim of the trial is to see if either of these tests will help doctors diagnose women with ovarian cancer when their cancer is at an early stage. The trial has recently closed and it will be a few years before we know the results.
Symptoms of ovarian cancer
Most women with early-stage cancer of the ovary don't have any symptoms for a long time. When symptoms occur they may include any of the following:
loss of appetite
vague indigestion, nausea, excessive gas (wind) and a bloated, full feeling unexplained weight gain
swelling in the abdomen – this may be due to a build up of fluid (ascites), which can cause shortness of breath
pain in the lower abdomen
changes in bowel or bladder habits, such as constipation, diarrhoea or needing to pass urine more often
lower back pain pain during sex
abnormal vaginal bleeding, although this is rare.
If you have any of the above symptoms it is important to have them checked by your doctor, but remember they are common to many other conditions and most women with these symptoms will not have cancer.
How ovarian cancer is diagnosed
Usually you begin by seeing your GP, who will examine you and arrange for you to have any tests (usually ultrasound scans and/or blood tests) that may be necessary. If your GP suspects that you have ovarian cancer they will refer you to a cancer centre to be seen by a specialist gynaecology cancer team for the tests and for specialist advice and treatment.
At the hospital
At the hospital, the gynaecologist (specialist in women's illnesses) will ask you about your general health and any previous medical problems, before examining you. This will include an internal (vaginal) examination to check for any lumps or swellings.
The specialist 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 whether there are higher than normal levels of the CA125 protein in your blood. CA125 is a protein that most women have in their blood. The level may be higher in women with ovarian cancer, as it is sometimes produced by ovarian cancer cells. However, CA125 is not specific to ovarian cancer, and the level can also be raised in women who have other non- cancerous conditions.
Several tests may be used to diagnose cancer of the ovary. The tests may also show the stage of the cancer – whether or not it has spread to other parts of the body. These tests help your doctor to know the best way to treat the cancer.
An ultrasound uses sound waves to build up a picture of the inside of the abdomen, the liver and the pelvis. It will be done in the hospital scanning department.
If you have a pelvic ultrasound you will be asked to drink plenty of fluids so that your bladder is full. This helps to give a clearer picture. Once you are lying comfortably on your back a gel is spread onto your abdomen. A small device, which produces sound waves, is then rubbed over the area. The sound waves are converted into a picture by a computer.
If you have a vaginal ultrasound scan, a probe with a rounded end is put into your vagina. The probe 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.
Pelvic or vaginal ultrasound can be used to check for any enlargement or abnormalities of the ovaries which may be due to a cyst or tumour. It can also be used to show the size and position of a cancer.
A CT (computerised tomography) scan takes a series of x-rays which builds up a three-dimensional picture of the inside of the body. The scan is painless but takes from 10 to 30 minutes. CT scans use a small amount of radiation, which will be very unlikely to harm you and will not 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 are allergic to iodine or have asthma you could have a more serious reaction to the injection, so it is important to let your doctor know beforehand. You will probably be able to go home as soon as the scan is over.
Having a CT scan
An MRI (magnetic resonance imaging) scan is similar to a CT scan, but uses magnetic fields instead of x-rays to build up a series of cross-sectional pictures of the body. During the test you will be asked to lie very still on a couch inside a metal cylinder that is open at both ends. The whole test may take up to an hour and is painless – although the machine is very noisy. You will be given earplugs or headphones to wear.
The cylinder is a very powerful magnet, so before going into the room you should remove all metal belongings. You should also tell your doctor if you have ever worked with metal or in the metal industry or if you have any metal inside your body (for example, a cardiac monitor, pacemaker, surgical clips, or bone pins). You may not be able to have an MRI because of the magnetic fields.
Some people are given an injection of dye into a vein in the arm, but this usually does not cause any discomfort. You may feel claustrophobic inside the cylinder, but you may be able to take someone with you into the room to keep you company. It may also help to mention to the staff beforehand if you do not like enclosed spaces. They can then offer extra support during your test.
Abdominal fluid aspiration
If there has been a build up of fluid in the abdomen, a sample of the fluid can be taken to check for any cancer cells. The doctor will use a local anaesthetic to numb the area before passing a small needle through the skin. Some fluid is drawn off into a syringe and examined under a microscope.
This operation allows the doctor to look at the ovaries, fallopian tubes, the womb and the surrounding area. It's done under a general anaesthetic. Most women usually go home the same day but you may have to stay in hospital overnight.
While you are under anaesthetic, the doctor makes 3–4 small cuts, approximately 1cm (½ inch) in length, in the skin and muscle of the lower abdomen. A thin fibre- optic tube (laparoscope) is then inserted. By looking through the laparoscope the doctor can look at the ovaries and take a small sample of tissue (biopsy) for examination under a microscope.
During the operation, carbon dioxide gas is passed into the abdominal cavity and this can cause uncomfortable wind and/or shoulder pains. The pain is often eased by walking about or by taking sips of peppermint water. If the pain continues when you are at home you should contact the hospital for advice.
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 anaesthetic have worn off.
Sometimes cancer of the ovary cannot be diagnosed before a full operation (laparotomy) is carried out.
It will probably take several days for the results of your tests to be ready and a follow- up appointment will be arranged for you before you go home. Obviously, this waiting period is an anxious time and it may help you to talk things over with a close friend, a relative, the hospital specialist nurse, or a support organisation.
Staging and grading of ovarian cancer
The stage of a cancer is a term used to describe its size and whether it has spread beyond its original area of the body. Knowing the extent of the cancer and the grade helps the doctors to decide on the most appropriate treatment. It's often not possible to stage an ovarian cancer before a laparotomy is done and the results of any
biopsies are known (see diagnosis). A commonly used staging system is described below.
Borderline tumours are made up of low-grade cells that are unlikely to spread. They are usually completely cured by surgery and rarely require further treatment.
Stage 1 ovarian cancer only affects the ovaries. This stage is divided into three sub- groups:
Stage 1a The cancer is only in one ovary Stage
1b There are tumours in both ovaries.
Stage 1c The cancer is either at stage 1a or 1b, and there are cancer cells on the surface of one of the ovaries, or in the fluid taken from within the abdomen during surgery, or the ovary has burst (ruptured) before or during surgery.
Stage 2 ovarian cancer has begun to spread outside the ovaries within the pelvis. There are three sub-groups:
Stage 2a The cancer has spread to the womb or fallopian tubes.
Stage 2b The tumour has spread to other structures within the pelvis, such as the rectum or bladder.
Stage 2c The cancer is either at stage 2a or 2b, and there are cancer cells on the surface of one of the ovaries, or in the fluid taken from within the abdomen during surgery, or the ovary has burst (ruptured) before or during surgery.
Stage 3 The cancer has spread beyond the pelvis to the lining of the abdomen (a fatty membrane called the omentum), and/or to abdominal organs such as the lymph nodes in the abdomen, or the upper part of the bowel.
Stage 3a The tumours in the abdomen are very small and cannot be seen except under a microscope.
Stage 3b The tumours in the abdomen can be seen but they are smaller than 2cm.
Stage 3c The tumours in the abdomen are larger than 2cm.
If the cancer comes back after initial treatment this is known as recurrent cancer.
Grading refers to the appearance of the cancer cells when they are looked at under the microscope. The grade gives an idea of how quickly the cancer may develop. There are three grades: grade 1 (low-grade), grade 2 (moderate-grade) and grade 3 (high-grade).
Low-grade means that the cancer cells look very like the normal cells of the ovary. They usually grow slowly and are less likely to spread.
Moderate-grade means that the cells look more abnormal than low-grade cells.
High-grade means that the cells look very abnormal. They are likely to grow more quickly and are more likely to spread.