Ovarian Cancer Prevention (PDQ®)
What is prevention?
Cancer prevention is action taken to lower the chance of getting cancer. By preventing cancer, the number of new cases of cancer in a group or population is lowered. Hopefully, this will lower the number of deaths caused by cancer.
To prevent new cancers from starting, scientists look at risk factors and protective factors. Anything that increases your chance of developing cancer is called a cancer risk factor; anything that decreases your chance of developing cancer is called a cancer protective factor.
Some risk factors for cancer can be avoided, but many cannot. For example, both smoking and inheriting certain genes are risk factors for some types of cancer, but only smoking can be avoided. Regular exercise and a healthy diet may be protective factors for some types of cancer. Avoiding risk factors and increasing protective factors may lower your risk but it does not mean that you will not get cancer.
Different ways to prevent cancer are being studied, including:
- Changing lifestyle or eating habits.
- Avoiding things known to cause cancer.
- Taking medicines to treat a precancerous condition or to keep cancer from starting.
General Information About Ovarian Cancer
Ovarian cancer is a disease in which malignant (cancer) cells form in the ovaries.
The ovaries are a pair of organs in the female reproductive system. They are in the pelvis, one on each side of the uterus (the hollow, pear-shaped organ where a fetus grows). Each ovary is about the size and shape of an almond. The ovaries make eggs and female hormones (chemicals that control the way certain cells or organs work in the body).Anatomy of the female reproductive system. The organs in the female reproductive system include the uterus, ovaries, fallopian tubes, cervix, and vagina. The uterus has a muscular outer layer called the myometrium and an inner lining called the endometrium.
Ovarian cancer is the leading cause of death from cancer of the female reproductive system.
Since 1992, the number of new cases of ovarian cancer has stayed about the same. The number of deaths from ovarian cancer has slightly decreased since 2002.
It is hard to find ovarian cancer early. Early ovarian cancer may not cause any symptoms. When symptoms do appear, ovarian cancer is often advanced.
See the following PDQ summaries for more information about ovarian cancer:
- Ovarian Cancer Screening
- Ovarian Epithelial Cancer Treatment
- Ovarian Germ Cell Tumors Treatment
- Ovarian Low Malignant Potential Tumors Treatment
- Genetics of Breast and Ovarian Cancer
Ovarian Cancer Prevention
Avoiding risk factors and increasing protective factors may help prevent cancer.
Avoiding cancer risk factors may help prevent certain cancers. Risk factors include smoking, being overweight, and not getting enough exercise. Increasing protective factors such as quitting smoking, eating a healthy diet, and exercising may also help prevent some cancers. Talk to your doctor or other health care professional about how you might lower your risk of cancer.
The following risk factors may increase the risk of ovarian cancer:
Family history of ovarian cancer
A woman whose mother or sister had ovarian cancer has an increased risk of ovarian cancer. A woman with two or more relatives with ovarian cancer also has an increased risk of ovarian cancer.
- BRCA1 or BRCA2 genes.
- Genes that are linked to hereditary nonpolyposis colorectal cancer (HNPCC; Lynch syndrome).
Hormone replacement therapy
The use of estrogen-only hormone replacement therapy (HRT) after menopause increases the risk of ovarian cancer. The longer estrogen replacement therapy is used, the greater the risk may be. It is not clear whether the risk of ovarian cancer is increased with the use of HRT that has both estrogen and progestin.
Having too much body fat, especially during the teenage years, is linked to an increased risk of ovarian cancer. Being obese is linked to an increased risk of death from ovarian cancer.
Being taller than 5 feet 8 inches is linked to an increased risk of ovarian cancer.
The following protective factors may decrease the risk of ovarian cancer:
The use of oral contraceptives ("the pill") lowers ovarian cancer risk. The longer oral contraceptives are used, the lower the risk may be. The decrease in risk may last up to 25 years after a woman has stopped using oral contraceptives.
Taking oral contraceptives increases the risk of blood clots. This risk is higher in women who also smoke. There may be a slight increase in a woman's risk of breast cancer during the time she is taking oral contraceptives. This risk decreases over time.
Pregnancy and breastfeeding
Pregnancy and breastfeeding are linked to a decreased risk of ovarian cancer. Ovulation stops or occurs less often in women who are pregnant or breastfeeding. Some experts believe that women who ovulate less often have a decreased risk of ovarian cancer.
Bilateral tubal ligation or hysterectomy
Some women who have a high risk of ovarian cancer may choose to have a prophylactic oophorectomy (surgery to remove both ovaries when there are no signs of cancer). This includes women who have inherited certain changes in the BRCA1 and BRCA2 genes or in the genes linked to hereditary nonpolyposis colon cancer (HNPCC). (See the PDQ summary on Genetics of Breast and Ovarian Cancer for more information.)
It is very important to have a cancer risk assessment and counseling before making this decision. These and other factors should be discussed:
- Early menopause: The drop in estrogen levels caused by removing the ovaries can cause early menopause. Symptoms of menopause include the following:
- Risk of ovarian cancer in the peritoneum: Women who have had a prophylactic oophorectomy continue to have a small risk of ovarian cancer in the peritoneum (thin layer of tissue that lines the inside of the abdomen). This may occur if ovarian cancer cells had already spread to the peritoneum before the surgery or if some ovarian tissue remains after surgery.
Cancer prevention clinical trials are used to study ways to prevent cancer.
Cancer prevention clinical trials are used to study ways to lower the risk of developing certain types of cancer. Some cancer prevention trials are conducted with healthy people who have not had cancer but who have an increased risk for cancer. Other prevention trials are conducted with people who have had cancer and are trying to prevent another cancer of the same type or to lower their chance of developing a new type of cancer. Other trials are done with healthy volunteers who are not known to have any risk factors for cancer.
The purpose of some cancer prevention clinical trials is to find out whether actions people take can prevent cancer. These may include eating fruits and vegetables, exercising, quitting smoking, or taking certain medicines, vitamins, minerals, or food supplements.
New ways to prevent ovarian cancer are being studied in clinical trials.
Clinical trials are taking place in many parts of the country. Information about clinical trials can be found in the Clinical Trials section of the NCI Web site. Check NCI's list of cancer clinical trials for ovarian cancer prevention trials that are now accepting patients.