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. 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, breast cancer or colon cancer 
• being of Ashkenazi Jewish descent^[2] 
• a mutation in 1 of several known genes, including BRCA1/2 
• having a genetic condition, such as Lynch syndrome, also known as hereditary nonpolyposis colon cancer or HNPCC) 
• increasing age – ovarian cancer is more common in women over 50 years of age 
• medical conditions such as endometriosis - Although some studies report an increased risk of ovarian cancer in women with a history of endometriosis, evidence suggests that the overall lifetime likelihood of developing ovarian cancer is low. 
• use of hormone replacement therapy (HRT) 
• smoking tobacco 
• 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 
• infertility treatment.^[3]