Breast Cancer
New Studies
Here's a classic example of the flaws in the medical research system - and the need to focus more resources on prevention.
The breast cancer drug Herceptin is given to the 20 percent of breast cancer patients whose tumors have a particular genetic characteristic. But now, nearly a decade after the drug's approval, evidence is emerging that the testing of the tumors can be highly inaccurate or that the wrong cutoff values are being used to determine who qualifies for treatment, reports the New York Times.
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It's a perfect reason why most studies should be taken with a grain of salt. After 10 years, the manufacturer sponsors a study which proves people may be under diagnosed and the test is not accurate enough.
Here's what The Times reported:
As many as 40 percent of women with early breast cancer might benefit from the drug but are not getting it, some experts say. Yet other women may be paying for the drug and risking its side effects unnecessarily.
Herceptin, also known as trastuzumab, works by blocking Her2, a protein that can spur growth of tumor cells. It is given only to women whose tumors have abundant amounts of the protein. There are two tests used to determine this. One looks at the amount of the protein on the surface of a sample of tumor cells. The other looks for extra copies of the gene that governs the production of Her2.
But two studies found that patients who were considered Her2-negative even using both tests benefited from Herceptin.
Both studies reanalyzed tumor samples from earlier clinical trials showing that Herceptin, if used after a tumor is removed by surgery, cuts the risk of the cancer's recurring by half. For a woman to have entered those trials, her tumor had to be classified as Her2-positive by a local clinical laboratory.
But scientists have now gone back and retested preserved tumor samples and found that as many as 20 percent of them were actually Her2-negative. Yet the women with those tumors also experienced a reduction in cancer recurrence from Herceptin, in some cases as great as that in the Her2-positive women.
Dr. Pamela M. Klein, an executive at Genentech, the manufacturer of Herceptin, said the company was continuing to explore how to best identify patients for the drug.
It left some doctors incredulous and uncertain how to treat their patients.
"Here we are, 10 years into it," said Dr. Marc L. Citron, an oncologist in Lake Success, N.Y., "and we don't know how to test for it."
One more reason to look at prevention and help women take responsibility and control over their own healthcare by getting smart and strong.
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