A risk factor is any factor that is associated with increasing someone’s chances of developing a certain condition, such as cancer. Some risk factors are modifiable, such as lifestyle or environmental risk factors, and others cannot be modified, such as inherited factors and whether someone in the family has had cancer.

Having 1 or more risk factors does not mean that you will develop cancer. Many people have at least 1 risk factor but will never develop cancer, while others with cancer may have had no known risk factors. Even if a person with cancer has a risk factor, it is usually hard to know how much that risk factor contributed to the development of their disease.

Factors that are associated with a higher risk of developing ovarian cancer include:

• a family history of ovarian cancer – the risk of developing ovarian cancer is higher if 1 or more blood relatives (such as mother, sister or daughter) has had ovarian cancer
• family history of breast or colon cancer
• a mutation in 1 of several known genes. Up to 15% of all cases of invasive ovarian cancer involve the inheritance of a mutated gene. Women who have inherited mutations in the BRCA1 or BRCA2 genes have a substantially increased risk of ovarian and breast cancer. Women with Lynch syndrome (also known as hereditary nonpolyposis colon cancer or HNPCC) also have an increased lifetime risk of ovarian cancer
• increasing age
• medical conditions such as endometriosis
• use of hormone replacement therapy (HRT)
• tobacco smoking
• obesity

Some factors reduce the risk of developing ovarian cancer. These include:

• having children
• use of the oral contraceptive pill (the pill)
• gynaecological surgery – tubal ligation (having your tubes tied)

It is not clear whether the following affect the risk of ovarian cancer:

• Diet
• Alcohol
• Aspirin and non-steroidal anti-inflammatory drugs
• Talc.

Find out more about:

• Position Statement on Testing for ovarian cancer in asymptomatic women 
• Frequently Asked Questions on Position Statement – Testing for Ovarian Cancer in Asymptomatic Women 
• Position Statement on genetic testing for women diagnosed with ovarian cancer
• Genetic testing for women diagnosed with ovarian cancer FAQs
• Position Statement on Lifestyle risk factors and the primary prevention of cancer
• Lifestyle and risk reduction tool
• Breast and ovarian cancer and inherited predisposition - educational genetics factsheet from NSW Health Centre for Genetics education.

Healthcare professionals

Healthcare professionals are encouraged to visit the eviQ referral guidelines for ovarian cancer risk assessment and consideration of genetic testing for evidence-based guidance on cases that warrant referral to a family cancer clinical for assessment, based on family history.

General practitioner referral guidelines for cancer genetics assessment can be found here.