- Early menarche/late menopause: Commencement of menstrual cycles (menarche) at an early age or cessation of menstrual cycles (menopause) at a later age than normal have been reported to elevate the risk of developing ovarian cancer.
- Family history: Risk of developing ovarian cancer increases in females with a history of ovarian, breast, and some other cancers in close relatives. The risk further increases with the increase in the number of affected relatives.
- Genetic Cancer Predisposition Syndromes: Some inherited cancer predisposition syndromes (caused by a mutation in certain genes which are generally transferred from one generation to other) have been reported to be associated with a high incidence rate of ovarian cancer.
Following are some examples: mutations in the genes BRCA1 and BRCA2, Cowden disease (caused due to defect in PTEN gene); Lynch syndrome (or hereditary nonpolyposis colon cancer [HNPCC] caused due mutation in genes: MLH1, MLH3, MSH2, MSH6, PMS1, PMS2, etc); Li-Fraumeni syndrome (caused due mutation in TP53 gene), etc.
- Delayed marriage or childbirth: It has been reported that women who got married at a later age and have pregnancy after 35 years of age or who never had a full-term pregnancy are at increased risk of developing ovarian cancer.
- Hormonal replacement therapy: Women who are using or have used hormone replacement therapy (HRT) after menopause for many years, are generally at higher risk of developing ovarian cancer.
- Endometriosis: Endometriosis is a condition characterized by the appearance of endometrial tissue at places other than the usual place (the uterus), such as on the ovaries, fallopian tubes, etc. This condition can increase the risk of ovarian cancer, especially clear cell and endometrioid type.
- Obesity: An increased body mass index or waist circumference has also been linked to increased risk of ovarian cancer.
- Age: Ovarian cancer generally occurs at higher age and risk increases with age.
Apart from the above-listed risk factors, certain factors which can reduce the risk of ovarian cancer have also been reported. Such protective factors may include the use of oral contraceptives or intrauterine devices for birth control, tubal ligation or hysterectomy (surgical removal of the uterus), breastfeeding, etc.