BOSTON – Fifty-three women around the nation are suing the drug companies who made and promoted a synthetic estrogen known as DES, or diethylstilbestrol, claiming it resulted in their developing breast cancer.

The drug was pulled from the market in 1971 after the U.S. Food and Drug Administration told doctors to stop prescribing DES for pregnant patients, after a study found that taking the drug during pregnancy appeared to increase the risk of a rare vaginal cancer.

Thousands of lawsuits were filed by “DES daughters” alleging links between DES and cervical and vaginal cancer, with many suits being settled out of court.

The Boston case is believed to be the first major litigation alleging a link between DES and breast cancer in DES daughters over the age of 40.

The lawsuit alleges that 14 drug manufacturers – including Eli Lilly and Co. and Bristol-Myers Squibb Co. – withheld from doctors and the FDA reports that showed DES did not prevent miscarriages and raised serious questions about the safety of the drug.

The drug companies, challenging the premise of any causal link between prenatal DES exposure and breast cancer, have a filed a motion before U.S. Magistrate Judge Marianne Bowler arguing that the testimony from the women’s experts are not based on reliable science and should be excluded.

If Bowler grants the drug companies’ motion, the case will not go to trial. But if she allows the plaintiffs’ experts to testify, the case can proceed to trial.

Final arguments on the motion are scheduled for Jan. 19 in U.S. District Court. •