About Ovarian Cancer Prevention

Key Points

  • In the U.S., a woman's lifetime risk of developing ovarian cancer is approximately 1.4%, or 1 out of 70 women.
  • Women who have a family history of ovarian and/or breast cancer, especially in first-degree relatives (mother, daughter, sister), have a greater chance of developing ovarian cancer than women without such a history.
  • An alteration in the BRCA1 or the BRCA2 gene increases a woman's lifetime risk of developing ovarian cancer to between 16% and 60%.
  • Monitoring for ovarian cancer in women at high genetic risk is recommended to begin between the ages of 25 and 35 (or 5-10 years before the earliest age at which ovarian cancer has been diagnosed in the family).
  • Current recommendations for ovarian cancer screening of women at high genetic risk include: CA-125 blood test once or twice a year and transvaginal ultrasound once or twice a year.
  • There is no evidence that following current screening recommendations results in detecting ovarian cancer at an earlier stage.
  • There is no evidence that screening improves the survival of women who are found to have ovarian cancer.
  • Risk-reducing surgery may result in an 85 to 95% reduction in the risk of ovarian cancer in women who carry a BRCA gene mutation.
  • Certain medications may lower the risk of ovarian cancer.

Genetic Risk

In the United States, a woman's lifetime risk of developing ovarian cancer is approximately 1.4%, or 1 out of 70 women. Women who have a family history of ovarian and/or breast cancer, especially in first-degree relatives (mother, daughter, or sister), have a greater chance of developing ovarian cancer than women who do not have close relatives affected with breast and/or ovarian cancer.

BRCA Gene Mutations

Women are at increased genetic risk of ovarian cancer if they have an alteration in certain [glossary term:] genes that have been linked with [glossary term:] hereditary breast and /or ovarian cancer. An alteration in the [glossary term:] BRCA1 or the [glossary term:] BRCA2 gene increases a woman's lifetime risk of developing ovarian cancer to between 16% and 60%. This broad range of estimates is due to differences in how the existing research studies have been done. However, there is no doubt that the risk of ovarian cancer is much greater in women who have a strong family history and/or a mutation in a BRCA gene than in women from the general population. In addition, the risk of ovarian cancer is clearly lower for women with BRCA2 mutations than it is for those who have BRCA1 mutations.

Early Detection

Reducing the burden of cancer is important to women who are at high genetic risk of ovarian cancer, and it is a major goal for the health care providers who treat these women. Like many other cancers, the survival rates for ovarian cancer are much higher when it is detected early. As a result, screening for ovarian cancer in high risk women is recommended to begin between the ages of 25 and 35 (or 5-10 years before the earliest age at which ovarian cancer has been diagnosed in the family).

Current Recommendations

Current recommendations for ovarian cancer screening of women at high genetic risk include:

It is important to understand that these recommendations are not supported by any evidence that using this screening program actually results in detecting ovarian cancer at an earlier-than-usual stage. Even more importantly, there is no evidence that screening improves the survival of women who are found to have ovarian cancer. Clearly, there is an urgent need for a proven, effective ovarian cancer screening strategy in women who are at increased genetic risk.

In addition to screening, there are also medical and surgical approaches to reducing the risk of ovarian cancer in high-risk women:

Risk-reducing Surgery

Risk-reducing [glossary term:] salpingo-oophorectomy (RRSO) involves removal of the [glossary term:] ovaries and [glossary term:] fallopian tubes before there is evidence that cancer has developed. It has been estimated that this procedure may result in an 85 to 95% reduction in the risk of ovarian cancer in women who carry a BRCA gene mutation. There is some uncertainty regarding precisely how much reduction in risk is achieved with surgery, in part due to the occurrence of an ovarian cancer-like illness (called primary peritoneal carcinoma) in some women who have had preventive surgery. Nonetheless, it is generally recommended that high-risk women seriously consider this procedure after they have completed their childbearing. In addition, there is some evidence to suggest that the risk of breast cancer is lower among women who have had their ovaries removed for preventive purposes.

Surgical removal of the ovaries from a woman who is still regularly having her periods results in loss of fertility and the premature (earlier-than-usual) onset of menopause. This is accompanied by the usual symptoms of menopause related to decreased levels of estrogen in the body. The decision to postpone surgery in some women is based upon their concerns regarding the long-term effects of premature menopause, such as increased risks of [glossary term:] osteoporosis (thinning of the bones) and [glossary term:] cardiovascular disease (including heart attack and stroke). Early menopause may also have a significant impact on a woman's quality of life. These issues have not been carefully studied in women at increased genetic risk of ovarian cancer. One of the main reasons that the current study is being done is to collect information on these important questions.

Furthermore, the risks and benefits of menopausal hormone therapy (MHT) in women with a BRCA mutation who have undergone RRSO have not been clearly defined. Currently, the decision regarding whether or not to use hormone therapy after risk-reducing surgery is made on an individual basis by each woman and her health care providers. Tubal ligation ("tying the tubes") may also help to reduce the risk of ovarian cancer without actually removing the ovaries. This avoids immediate menopause, but does not reduce cancer risk as much as RRSO does.

Medical Prevention

The use of oral contraceptives (birth control pills) has been shown to reduce the risk of ovarian cancer by about 50% among women in the general population, but information about the potential risks and benefits of oral contraceptives among women with BRCA1 and BRCA2 gene mutations is limited. One study has shown a decreased risk of ovarian cancer following the use of oral contraceptives in high-risk women, while another has shown no evidence of risk reduction. Therefore, there is currently no consensus among health care providers involved in caring for high-risk women as to whether oral contraceptives should or should not be used. In addition, there is both a theoretical concern, and a limited amount of data, to suggest that the risk of breast cancer may be increased with oral contraceptive use in high-risk women.

Finally, there is a great deal of research currently underway, aimed at identifying other medications which might be used to lower the risk of ovarian cancer. The technical term for such treatments is [glossary term:] chemoprevention. Various different medications are being evaluated to see if they might be safe and effective in reducing the chances that high-risk women will develop ovarian cancer and may be found by searching NCI's PDQ database.