The exact cause of cancer is unknown.  However, doctors have observed that women who ovulate (having ovulation/menses) more frequently have a higher risk of developing cancer.  The theory goes that ovulation causes injury to the epithelial layer of the ovary, which requires the body to repair it.  Ovulation, therefore, correlates to this ovarian epithelial layer “injury – repair cycle.” At some point, the patient’s body could not repair the injury correctly and the ovarian epithelial layer injury results in cancer.  This theory explains why women who do not ovulate as much, for example by taking birth control pills or having many children, have a much-reduced rate of ovarian cancer. 

Although the majority of patients develop ovarian cancer randomly as explained earlier, about 5-10 percent of ovarian cancers can be traced mostly to a hereditary gene called BRCA1. BRCA1 is a tumor suppressor gene, which is found dysfunctional in patients with hereditary ovarian cancer.  Other types of hereditary ovarian cancer are site-specific ovarian cancer families and the hereditary non-polyposis colorectal cancer family.  Having a dysfunctional BRCA1 gene predisposes women to having a 25-50 percent risk of developing ovarian cancer and 40-80 percent risk of developing breast cancer.  Doctors usually recommend for a patient with the BRCA1 mutation, a prophylatic removal of ovaries and breast when she has completed her childbearing. Interestingly, women with hereditary ovarian cancer are usually diagnosed in their early 40s, as compared to their 60s for women with nonfamilial ovarian cancer.   

Diet has been shown to play a part in ovarian cancer.  Women whose diet is high in animal fat and meat have a two-fold increase in ovarian cancer than women with a lower consumption of these products.  Industrialized Western countries have high meat and animal fat diets and have been shown to have greater incidence of ovarian cancer than other countries.   

Certain chemicals have been implicated as causative agents of ovarian cancer.  These chemicals include talc and asbestos.  The theory is that talc particles travel through the cervix up to the ovaries when applied to the genital area.  This can then cause toxic effects on the ovaries. 

Multiple things can be done to reduce the risk of ovarian cancer; most are associated with the interruption of ovulation.  Women who use oral contraceptives reduce their risk of ovarian cancer by 40 to 50 percent over nonusers.  The longer the pills are used, the greater the protection they offer.  Women who have been pregnant reduce their risk of ovarian cancer 30 to 60 percent than women who have never been pregnant.  With each pregnancy, the protective effect increases.  Women can reduce their risk of ovarian cancer by having their ovaries removed, but this does not eliminate the risk completely and is controversial.