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Known Health Effects for Women Prescribed DES While Pregnant

		Known Health Effects
		Overview Known Health Effects for Women Prescribed DES While Pregnant Known Health Effects for DES Daugthers Known Health Effects for DES Sons

• their increased risk of breast cancer, and
• steps that should be taken for detecting breast cancer early.

Women prescribed DES while pregnant are at a modestly increased risk for developing breast cancer. Studies have consistently reported an increased risk of approximately 30% for women prescribed DES while pregnant. The most recent study, published in the British Journal of Cancer (Titus-Ernstoff, 2001), included more than 6,000 women and compared breast cancer rates of women exposed to DES with rates among women who were not exposed. This study followed participants over a longer period of time than earlier research on breast cancer risks associated with DES. The researchers' findings were consistent with earlier studies, confirming an increased breast cancer risk of approximately 30% for women prescribed DES while pregnant. That means when considering breast cancer risks across a lifetime, one in six women prescribed DES during pregnancy will get breast cancer. In comparison, only one in eight unexposed women will get breast cancer across their lifetime.

Early studies of women prescribed DES while pregnant were inconclusive. Even now, not all researchers agree that there is a link between DES exposure and breast cancer. Despite differences of opinion, the 2001 British Journal of Cancer study is important for two reasons. First, it is the largest study of its kind. Second, participants in the 2001 study were older than participants in previous studies; as women grow older, their chances for developing breast cancer increase, regardless of whether they were exposed to DES. Because participants were older, many more women had breast cancer in the 2001 study than in earlier studies. This provides the 2001 study with more "power" to detect meaningful differences between the rates of breast cancer among women who were and were not exposed to DES. In other words, the more women included in a study, the less likely that the results of the study can be considered chance. Now researchers can confirm with a higher degree of certainty that women prescribed DES while pregnant have a modestly increased risk of breast cancer.

Exposure to DES while pregnant is just one of many factors that can increase a woman's chance of developing breast cancer. Several other factors can further increase the risk for breast cancer, including personal and family history of breast cancer, genetics, diet and lifestyle choices, use of hormone replacement therapy (HRT), and having children later in life. In addition, as women grow older, their chances of developing breast cancer increase, regardless of whether they were exposed to DES. The following chart explains the increasing risk for breast cancer as a woman ages. This chart illustrates breast cancer risk for women who were not exposed to DES while pregnant.

Source: National Cancer Institute Surveillance, Epidemiology,
and End Results Program, 1995-1997.

You should follow a regular schedule for the breast cancer screening recommended by your health care provider. The types and timing of the screening should be based on your risk factors for breast cancer. Talk with your health care provider about when you should start screenings for breast cancer and how often you should be checked. Your health care provider may recommend that you learn and practice breast self-examination as a way to detect any lumps in your breasts, discharge from the nipples, or skin changes (such as dimpling or puckering). Most health care providers will recommend that women 40 years of age and older have a mammogram (an X-ray of the breast) every 1-2 years. In addition, most health care providers perform clinical breast examinations (visual and manual examination of the breast) during routine physical examinations.

For more information about breast cancer causes and prevention, visit the NCI Web site at www.cancer.gov or call the Cancer Information Service (CIS) toll-free 1-800-4-CANCER (1-800-422-6237).

To learn more about the risk of breast cancer for women prescribed DES while pregnant, refer to Recent DES Research and DES Bibliography.

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