Causes of Ovarian Cancer

Sporadic Cases

Why some women get ovarian cancer and others do not is unknown in the majority of cases of ovarian cancer. As stated in the risk factor section, some factors increase the risk of getting ovarian cancer while others decrease the risk. Risk factors are not definitive predictors for the disease, except when a woman has inherited genetic mutations that are clearly associated with ovarian cancer.

Risk factors, however, do give researchers clues as to what might be responsible for ovarian cancer. Factors that limit the amount of times the ovaries release an egg, such as pregnancy and taking birth control pills, may lower the risk of the disease because there might be a relationship between ovulation (egg release)/hormonal changes and ovarian cancer.

Cancer usually is the result of small changes to the DNA that make up the genes inside the nucleus of the cells in our body. Some of these genetic changes occur spontaneously or randomly, as a result of damage caused by external forces. Cancers that arise this way are called “sporadic” (as opposed to “inherited,” which are discussed below). For those genetic mutations not inherited from our parents, researchers now have a greater understanding how these changes can cause these cells to become cancerous.

Scientists know, for example, that ultraviolet radiation and carcinogens in the diet and environment mutate certain genes, called oncogenes. These genetic changes alter the growth machinery of the cell, causing the cell and its progeny cells to replicate out of control. Ovarian cancer may result from a chemical agent that somehow penetrates the vagina, uterus and fallopian tubes, affecting certain genes in these cells, which might explain why hysterectomy and tubal ligation protects against the disease, according to the American Cancer Society. OCRF researchers are trying to identify the genes implicated in sporadic ovarian cancer to better understand what causes the disease, how to diagnose it earlier and to develop better treatments.

Inherited Cases

Some changes to our DNA, which can increase our risk for certain diseases, are inherited from our parents. Inherited mutations in the BRCA1 and BRCA2 account for 10 percent of all epithelial ovarian cancers. These mutations are often found in families with a strong history of ovarian or breast cancer. A woman gets these flawed genes from one or both of her parents, and the mutation present in every cell of the body increases her risk for both ovarian and breast cancer, as well as other cancers. These genes, which act in a dominant fashion, normally code for what is called a tumor suppressor, a protein that acts to keep cells growing normally. The mutant protein does not function properly and the cells grow uncontrollably.

It is important to note that not every woman in very high risk families carry these mutations. Not every cancer in such families is linked to the harmful mutations in these genes and not every woman who has these mutations will develop ovarian and/or breast cancer. But, according to the National Cancer Institute, women in the general population have a 1.4 percent (14 out of 1,000) lifetime risk of getting ovarian cancer compared to a 15 percent to 40 percent lifetime risk of getting ovarian cancer for women (150–400 out of 1,000) who have a BRCA1 or BRCA2 mutation.

If you tested negative for the BRCA mutations, but are concerned about your genetic risk and would like more information, you may want to visit The Ferre Institute for more information.