Unlike breast cancer, cervical cancer and bowel cancer, there is no free national screening programme for ovarian cancer.
Most ovarian cancers are diagnosed at an advanced stage, when they have already spread. Clearly, it would be very helpful to have a screening programme so that ovarian cancer can be diagnosed at an early stage when it is much easier to treat.
Three potential methods of screening for ovarian cancer have been assessed:
1. Internal examination can be performed to identify enlarged ovaries. Although internal examination can detect large ovarian tumours even experienced doctors are not able to reliably detect ovarian cancer at an early stage. Internal examination is not regarded as an effective method for early detection of ovarian cancer.
2. CA125 is a protein released into the blood in high levels in most women with ovarian cancer. The CA125 blood test is frequently used to diagnose ovarian cancer in women who have symptoms and to monitor women after and during treatment of ovarian cancer. It is important to recognise that CA125 is also produced by many normal tissues and levels in the bloodstream can therefore also be raised in normal situations (e.g. pregnancy, menstruation) and benign conditions as well as ovarian cancer. The CA125 test is easily and quickly performed on a small blood sample sent to the laboratory.
3. Ultrasound scanning can look at the size and texture of the ovaries. In ovarian cancer the ovaries increase in size and the texture becomes abnormal due to formation of cysts and solid growths. Some of these abnormal features also occur in benign ovarian tumours and other conditions in the pelvis. So, as with CA125, it is important to realise that ultrasound results can be abnormal even when there is no cancer present.
Some large studies have looked at using either CA125 or ultrasound to screen for ovarian cancer.
One large study of over 200,000 women was the UKCTOCS (UK Collaborative Trial of Ovarian Cancer Screening) study. Women who agreed to take part were randomly allocated to be screened with either CA125 or ultrasound, or to a control group who were followed up without screening. Initial results have not shown that this sort of screening is effective enough to be adopted as a national programme. The study results are still being analysed and the women who took part are still being followed-up to see if the effectiveness of the screening can be demonstrated to save lives.
What are the problems with screening for ovarian cancer?
False positive results are often found.
The major problem with screening for ovarian cancer is that both the CA125 test and ultrasound scanning can be abnormal in women who do not have ovarian cancer. These sorts of results, known as false positives, are a serious problem as they can cause a great deal of anxiety. Even worse, if the abnormalities persist, it may ultimately be necessary to perform an operation to remove the ovaries and tubes in order to exclude the possibility of ovarian cancer which turns out to have been unnecessary. As ovarian cancer is relatively uncommon it works out that more abnormal screening results are due to false positive findings than are due to cancer.
False negative results can occur.
Most women find a normal screening result reassuring. However, it should be recognised that neither CA 125 or ultrasound will pick up every case of ovarian cancer. False negative results do occur and a small number of women will be falsely reassured.
Screening and you
Many women are concerned about their risk of developing ovarian cancer, particularly if they have a friend or relative who has developed the cancer. Women with this first-hand experience of ovarian cancer often wish to be screened. You can arrange for a private CA125 test and ultrasound.
Women with a family history can ask their GP for a referral to a specialist genetics centre to see if they are carrying a BRCA gene mutation that will increase their risk.
Last review April 2018
Date of next review April 2020