BOSTON (AP) -- Eli Lilly and Co. has settled a lawsuit brought by four sisters who contended their breast cancer was caused by a drug their mother took during pregnancy in the 1950s, a move some believe could trigger financial settlements in scores of other claims brought by women around the country.

A total of 51 women, including the Melnick sisters, filed lawsuits in Boston against more than a dozen companies that made or marketed a synthetic estrogen known as DES.

The Melnick sisters' case was the first to go to trial. The settlement was announced Wednesday on the second day of testimony.

DES, or diethylstilbestrol, was prescribed to millions of pregnant women over three decades to prevent miscarriages, premature births and other problems. It was taken off the market in the early 1970s after it was linked to a rare vaginal cancer in women whose mothers used it. Studies later showed the drug didn't prevent miscarriages.

Attorney Aaron Levine, representing the Melnick sisters, told the jury during opening statements that Eli Lilly failed to test the drug's effect on fetuses before promoting it as a way to prevent miscarriages.

Lawyer James Dillon, for Indianapolis-based Eli Lilly, told the jury that there was no evidence the drug causes breast cancer in the daughters of women who took it.

Dillon also said that no medical records show that the mother of the Melnick sisters took DES or that, if she did take it, it was made by Eli Lilly. Leading researchers at the time recommended that DES be used for pregnant women who had consecutive miscarriages, he said.

DES was not patented and was made by many companies.

Boston attorney Andrew Meyer, who's handled numerous medical malpractice cases, said the settlement in this case could signal settlements in other cases.

"When one settles a case, they recognize they can lose it," he said. "The reason they can lose it is because there's enough evidence for the plaintiffs to be able to win it. So it's not just optics, it isn't."

Columbus, Ohio, resident Irene Sawyer also is suing Eli Lilly, alleging that her prenatal exposure to DES caused her breast cancer. She called the settlement "a huge victory" for DES daughters.

"The bottom line is that this company put out a drug without testing, without knowing the consequences of this drug," she said.

It's wonderful, she said, that drug companies "are starting to realize this is not right, that there are consequences."

The Melnick sisters, who grew up in Tresckow, Pa., said they all developed breast cancer in their 40s.

Levine told the jury that their mother did not take DES while pregnant with a fifth sister and that sister has not developed breast cancer.

The four Melnick sisters also had miscarriages, fertility problems or other reproductive tract problems long suspected of being caused by prenatal exposure to DES. They were diagnosed with breast cancer between 1997 and 2003 and had treatments ranging from lump-removal surgery to a full mastectomy, radiation and chemotherapy.

Thousands of lawsuits have been filed alleging links between DES and vaginal cancer, cervical cancer and fertility problems. Many of those cases were settled.

Associated Press writer Jay Lindsay contributed to this report.

Copyright 2013 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.