It is not known what causes ovarian cancer, but there are risk factors that can increase the chances of a woman developing this disease. Like all cancers, ovarian cancer occurs when normal cells mutate and become abnormal, growing rapidly and outliving the normal cells in the body. One of the likely underlying causes of ovarian cancer is the presence of certain hormones, such as androgen and estrogen. Some other possible causes of ovarian cancer include long-term use of fertility drugs, the presence of a uterus and a lack of past pregnancies. While some possible causes are generally avoidable, there are some risk factors that are not, such as age and history of cancer.
One of the likely causes of ovarian cancer is an overabundance of certain hormones, usually the result of hormone replacement therapy. For example, some studies show that women who take estrogen to quell the symptoms of menopause may increase their risk of getting ovarian cancer. This is especially true for women who take estrogen alone for at least five years, while women who take a combination of estrogen and progesterone have a lower risk of ovarian cancer. Some women have also taken androgens, which are male hormones. Doing so also may increase the risk of ovarian cancer.
Studies have shown that having children and breastfeeding can both reduce the risk of ovarian cancer, meaning not having children and never breastfeeding may result in slightly higher chances of getting this disease. At the same time, trying to get pregnant through the use of a fertility drug known as clomiphene citrate can increase the risk of ovarian cancer, especially when this drug is taken for more than a year. Women who decide not to have children may benefit from having a hysterectomy to remove the uterus, because this can reduce the risk of ovarian cancer, as can getting one's fallopian tubes tied.
Some causes of ovarian cancer cannot be avoided, because they have to do with either medical history or genetics. For example, women previously diagnosed with breast cancer tend to have an increased risk of getting ovarian cancer, as do those with family members who have been diagnosed with ovarian, colon or breast cancer. Genetic mutations are also sometimes considered causes of ovarian cancer. The presence of breast cancer gene 1 and breast cancer gene 2, for instance, can indicate an increased possibility of developing both breast cancer and ovarian cancer. Finally, age is also a factor; women over 55 and those who have been through menopause have an increased risk of this disease.