What causes (epithelial) ovarian cancer?

Average rating:

A cancerous tumour starts from one abnormal cell. The exact reason why a cell becomes cancerous is unclear. It is thought that something damages or alters certain genes in the cell. This makes the cell abnormal and multiply 'out of control'. (See separate leaflet called 'Cancer - What Causes Cancer' for more details.)

In most cases, the reason why an ovarian cancer develops is not known. However, there are factors which are known to alter the risk of ovarian cancer developing. These include:

Age. Most cases occur in women over the age of 50 years.
Ovulation factors. Factors that reduce the number of times a woman will ovulate slightly lowers the risk. For example, taking the combined oral contraceptive pill, having children and breastfeeding. In contrast, not having children and having a late menopause slightly increases the risk.
Being overweight or obese increases the risk.
Taking HRT (hormone replacement therapy) may slightly increase the risk.
Sterilisation or hysterectomy (removal of the uterus) appears to reduce the risk slightly.
Taking the combined oral contraceptive pill provides some protection from ovarian cancer. This protection seems to continue for many years after stopping the pill.
Genetic factors - see below.

Family history and genetic testing
Most cases of ovarian cancer are not due to genetic or hereditary factors. Around one in twenty cases are due to faulty genes which increase the risk of cancer of the breast and ovary. Some women are referred for genetic testing if a faulty gene is suspected on the basis of a strong family history of cancer. The commonest genes are BRCA1 and BRCA2. For example, if you have two or more close relatives who have had ovarian or breast cancer at a young age, (or certain other cancers), you may benefit from genetic testing. If this applies to you then it is advised that you see your GP to talk it through to see if you should be referred for genetic testing.

In addition, if you are eligible for enhanced breast screening due to a family history of breast cancer, you should be aware of the early symptoms of ovarian cancer (see below). See a doctor promptly if you develop any of these symptoms.