What are the risk factors?

The causes of ovarian cancer are largely unknown, but factors that can increase the risk of developing ovarian cancer include:

• age – ovarian cancer is most common in women over 50 and in women who have stopped having periods (have been through menopause), and the risk increases with age
• genetic factors – up to 20% of serous ovarian cancers (the most common subtype) are linked to an inherited faulty gene, and a smaller proportion of other types of ovarian cancer are also related to genetic faults
• family history – having one or more close blood relatives (e.g. mother, sister) diagnosed with ovarian, breast, bowel or uterine cancers, or having Ashkenazi Jewish ancestry
• endometriosis – this condition is caused by tissue from the lining of the uterus growing outside the uterus
• reproductive history – women who have not had children, who have had assisted reproduction (e.g. in-vitro fertilisation or IVF), or who have had children after the age of 35 may be slightly more at risk
• lifestyle factors – some types of ovarian cancer have been linked to smoking or being overweight
• hormonal factors – such as early puberty or late menopause.

Some studies suggest that menopause hormone therapy (MHT), previously called hormone replacement therapy (HRT), may increase the risk of ovarian cancer, but the evidence is not clear.

Some factors reduce the risk of developing ovarian cancer. These include having children before the age of 35; breastfeeding; using the combined oral  contraceptive pill. for several years; and having your fallopian tubes tied (tubal ligation) or removed.

Does ovarian cancer run in families?

Ovarian cancer most often occurs for unknown reasons. But some cases are due to an inherited faulty gene. Having an inherited faulty gene does not mean you will definitely develop ovarian cancer, and you can inherit a faulty gene without having a history of cancer in your family.

About 15% of women with ovarian cancer have an inherited fault in the BRCA1 or BRCA2 genes or other similar genes. The BRCA gene faults can also increase the risk of developing breast cancer.

Less commonly, a group of gene faults known as Lynch syndrome is associated with ovarian cancer and can also increase the risk of developing cancer of the bowel or uterus.

As other genetic conditions are discovered, they may be included in genetic tests for cancer risk.

Listen to our podcast episode ‘Genetic Tests and Cancer’