Drug cuts risk of breast cancer in high-risk women
June 4, 2011
Allison Cross
STAFF REPORTER
A drug that suppresses estrogen production significantly reduces the risk of breast cancer in women with a high likelihood of developing the disease, say new results from a Canadian-led clinical trial.
The international clinical trial, which followed more than 4,500 post-menopausal women from Canada, the United States, Spain and France over five years, found the drug exemestane reduced the risk of breast cancer by 65 per cent compared with the placebo.
The drug is currently being use to stave off reoccurrences in breast cancer patients.
At the three-year mark during the trial, there were 11 cases of invasive breast cancers in the group of women taking exemestane, and 32 in the placebo group.
There were also fewer cases of precancerous lesions in the women taking the drug compared to the women taking the placebo.
“We’re proud. We’re excited,” said Dr. Michael Wosnick, vice-president of research for the Canadian Cancer Society, which funded the trial. “This is a whole new piece in the arsenal . . . against breast cancer.”
Exemestane comes from a class of drugs called aromatase inhibitors, which suppress estrogen production.
“We know that estrogen is a strong fuel for breast cancer and so (for) women who have been diagnosed . . . standard treatment in the past would be, once diagnosed and treated, to try and knock down the estrogen levels as much as you can so you take the fuel away,” Wosnick said.
The findings of the trial, led by the NCIC Clinical Trials Group, were presented Saturday at the annual meeting of the American Society of Clinical Oncology and published in the New England Journal of Medicine.
The study’s participants all had risk factors for developing breast cancer, which include family history of the disease, current age, age at first menstrual period and age at birth of first child.
Vi Siemens decided to participate in the trial along with her three sisters. The four of them lost their 66-year-old mother to breast cancer in 1983.
They’ve also lost two aunts to the disease.
“We were all young moms when our mom died. We were all very aware of this disease,” Siemens told the Star from her home near Portage la Prairie, Man. “Everybody knows somebody who’s had breast cancer in their family. Somebody has to test these drugs.”
Save for non-melanoma skin cancer, breast cancer is the most prevalent cancer to afflict Canadian woman.
Roughly 23,400 will receive the diagnosis in 2011. About 5,100 won’t survive it.
Whether or not exemestane is implemented as a routine treatment for women at a high-risk of developing breast cancer will be up to the drug manufacturer and Health Canada, Wosnick said.
“We would hope that this drug or similar drugs would be made available to women who are at increased risk of breast cancer,” he said.
The Canadian Institutes of Health Research and drug manufacturer Pfizer Inc. also supplied funding for the trial.
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