Once-popular drug may up risk of cancer

Daughters of women who took an anti-miscarriage pills during the 1950s and 60s could have double the risk of developing breast cancer after age 40 and are 50 percent more likely to suffer from early menopause, according to a study by three Boston University professors who collaborated with researchers across the country.

Lead researcher and Slone Epidemiology Center senior epidemiologist Julie Palmer said women who think they may be at risk should ask their mothers if they took the drug.

Diesthylstilbestrol was widely used in the 1950s and 60s. One million to 2 million women were prenatally exposed to DES, according to the study.

DES is a synthetic estrogen. Estrogen is needed for the placenta to be properly sustained, and women who miscarry usually have low estrogen levels, Palmer said. By taking the drug, women would presumably be less likely to miscarry. It was later found the drug was ineffective in preventing miscarriages.

Initially, DES was only prescribed to women with a history of two of more miscarriages, but physicians began prescribing the drug to any pregnant woman, Palmer said.

Palmer said more than 20 years ago, one of her colleagues was a DES-exposed daughter. The colleague had suffered from cancer of the reproductive tract at age 20. Fifteen years ago, the woman and other activists for the cause went to Slone with an interest in researching the issue of DES-exposure complications. BU had been in charge of one of the groups and combined its work with other existing research groups across the country, Palmer said.

Many women may not even know they took the drug, because they were told it was a vitamin or good for the pregnancy, Palmer said.

Palmer said in 1971, DES was found to cause a higher risk of cervical and vaginal cancer.

"The adverse DES health effects are ongoing," she said. "Doctors think of DES as something that happened in the 1970s."

BU School of Public Heath epidemiology professor Elizabeth Hatch, a co-investigator in the study, formerly worked with the National Cancer Institute where she first began working on the study. At the Institute, she was the project coordinator for the five centers that worked on the research. After working there for 10 years, she began working in SPH on the BU portion of the study.

"We wish there were some definitive marker or genetic change to determine if you were exposed, but there isn't," Hatch said.

Palmer said women should have annual Pap smears and inform their gynecologist they were exposed in utero to DES. At age 40, the risk increases, and women should closely follow screening recommendations, she said.

"For daughters born in the 1950s and 1960s, prenatal records during a mother's pregnancy have been destroyed long ago," she continued. "It's worth asking their mothers if they took [DES]."

The drug was used across the country, but New England, New York, California and the Mid-Atlantic states were some of the geographic "hotspots," Hatch said.

She said clinical trials in the early 1950s had determined DES had no benefit in preventing miscarriages or prematurity, but physicians continued to prescribe it.

On average, women who were exposed to DES in utero also went into menopause nine months earlier than women who had not been exposed to the drug.

"It doesn't sound like a lot, but it's significant," Hatch said. "It's used as a marker of reproductive health."

There are risks to going through menopause both earlier and later, she said.

SPH epidemiology professor Lauren Wise also worked on the study. BU, alongside Dartmouth Medical School, Baylor Medical School in Houston, University of Chicago, the National Cancer Institute and New England Medical Center collaborated on the research.

The study, "Prenatal Diesthylstilbestrol Exposure and Risk of Breast Cancer," appeared in the August 2006 edition of the Cancer Epidemiology Biomarkers & Prevention.