A group of B.C. breast cancer surviviors have won the right to proceed in a class-action lawsuit against the makers of the hormone replacement drug Premarin. (CBC)

The maker of a hormone replacement drug that's been blamed for higher rates of breast cancer has lost its bid to block a B.C. class-action lawsuit.

The Supreme Court of Canada on Thursday declined to hear an appeal from Wyeth-Ayerst International, which makes the drugs Premarin and Premplus.

Hundreds of B.C. women claim they got breast cancer after taking the medication to ease symptoms of menopause, such as hot flashes and night sweats.

'Several thousand women who contracted breast cancer after using Premarin or Premplus and would be eligible to participate in the case.'—Plaintiff lawyer David Klein

Wyeth asked the B.C. Court of Appeal last year to dismiss the proposed lawsuit on the grounds that Canadian residents, including lead plaintiff Dianna Stanway, don't have jurisdiction to sue the American defendant.

The B.C. court dismissed that appeal, which Wyeth then unsuccessfully tried to take to the Supreme Court of Canada.

Stanway, of Sechelt, B.C., referred questions to her lawyer Thursday.

David Klein said he's pleased by the high court's ruling, which paves the way for the class-action lawsuit to be certified, likely in December. He said it would be about two years after that before a trial would begin.

Klein said his firm has been contacted by more than 100 B.C. women, though the total number affected could be much larger.

Hormone therapy in decline

"Our expert estimates that there are about 1,000 fewer cases of breast cancer [every year] as a result of the decline in use of hormone replacement therapy in Canada," he said.

"There are several thousand women there who contracted breast cancer after using Premarin or Premplus and would be eligible to participate in the case."

A Wyeth spokesperson could not immediately be reached for comment.

The B.C. Court of Appeal judgment made this past February noted that Wyeth argued its U.S. parent company never marketed the drugs in Canada, nor supplied them to Canadians.

"They submitted they have no real and substantial connection with British Columbia and the court does not have territorial competence to deal with the action against them," the judgment said.

Klein said the lawsuit is specifically against three Canadian and three American Wyeth companies. He said there was no doubt the case would go forward against the Canadian defendants, but it was important to keep the U.S. defendants involved because of their larger assets.

A major study published in 2002 linked the drugs to higher rates of heart attack, stroke and cancer.

Klein said well over 1,000 lawsuits have been filed against Wyeth in the United States concerning those two drugs.