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.
In recent years, there has been a small decrease in the number of new cases of ovarian cancer and the number of deaths from ovarian cancer. New cases of ovarian cancer and deaths from ovarian cancer are higher among white women than black women, but have decreased in both groups.
Women who have a family history of ovarian cancer and/or certain inherited gene changes, such as BRCA1 or BRCA2 gene changes, have a higher risk than women who do not have a family history or who have not inherited these gene changes. For women with inherited risk, genetic counseling and genetic testing can be used to find out more about how likely they are to develop ovarian cancer.
See the following PDQ summaries for more information about ovarian cancer:
- Genetics of Breast and Gynecologic Cancers (written for health professionals)
- Ovarian Cancer Screening
- Ovarian Epithelial Cancer Treatment
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 are risk factors for 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.
The risk of ovarian cancer is also increased in women who have certain inherited syndromes that include:
- Familial site-specific ovarian cancer syndrome.
- Familial breast/ovarian cancer syndrome.
- Hereditary nonpolyposis colorectal cancer (HNPCC; Lynch syndrome).
Hormone replacement therapy
The use of estrogen-only hormone replacement therapy (HRT) after menopause is linked to a slightly increased risk of ovarian cancer in women who are taking HRT or have taken HRT within the past 3 years. The risk of ovarian cancer increases the longer a woman uses estrogen-only HRT. When hormone therapy is stopped, the risk of ovarian cancer decreases over time.
It is not clear whether there is an increased risk of ovarian cancer with the use of HRT that has both estrogen and progestin.
Weight and height
Being overweight or obese during the teenage years, and gaining 40 or more pounds during adulthood is linked to an increased risk of ovarian cancer. Being obese is linked to an increased risk of death from ovarian cancer. Being tall (5'8" or taller) may also be linked to a slight increase in the risk of ovarian cancer.
The following are protective factors for ovarian cancer:
Taking oral contraceptives ("the pill") lowers the risk of ovarian cancer. The longer oral contraceptives are used, the lower the risk may be. The decrease in risk may last up to 30 years after a woman has stopped taking oral contraceptives.
Taking oral contraceptives increases the risk of blood clots. This risk is higher in women who also smoke.
Breastfeeding is linked to a decreased risk of ovarian cancer. The longer a woman breastfeeds, the lower her risk of ovarian cancer.
Some women who have a high risk of ovarian cancer may choose to have a risk-reducing salpingo-oophorectomy (surgery to remove the fallopian tubes and ovaries when there are no signs of cancer). This includes women who have inherited certain changes in the BRCA1 and BRCA2 genes or have an inherited syndrome. (See the Risk-reducing salpingo-oophorectomy section in the PDQ health professional summary on Genetics of Breast and Gynecologic Cancers for more information.)
It is very important to have a cancer risk assessment and counseling before making this decision. These and other factors may 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 risk-reducing salpingo-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.
It is not clear whether the following affect the risk of ovarian cancer:
Studies have not shown a link between drinking alcohol and the risk of ovarian cancer.
Aspirin and non-steroidal anti-inflammatory drugs
Some studies found a very small increased risk of one rare type of ovarian cancer in women who were current smokers compared with women who never smoked.
Overall, studies in women using fertility drugs have not found clear evidence of an increased risk of ovarian cancer. Risk of ovarian borderline malignant tumors may be higher in women who take fertility drugs. The risk of invasive ovarian cancer may be higher in women who do not get pregnant after taking fertility drugs.
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.