Breast cancer continues to be over-diagnosed

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When it comes to breast cancer and the too common phenomenon of over-diagnosis, it seems as though new studies emerge continually. Nearly all of them suggest that far too many women are being screened and treated unnecessarily.

For instance, in April, epidemiologists from Norway estimated that 15 to 25 percent of breast cancers found by mammograms were being treated unnecessarily. That same month, a study in the Annals of Internal Medicine calculated that, over a ten-year period, only one breast-cancer death was averted for every 2,500 women offered mammograms. Of these women, the mammograms led to the unnecessary treatment of six to 10 women, who were subjected to surgery, radiation and/or chemotherapy.

Yet unnecessary treatment can only be determined after the fact, and since many clinicians believe it is too risky to leave breast cancer untreated, they often proceed with further procedures. "I don't know anyone who offers women the option of doing nothing," says Eric Winer, director of the breast cancer program at Dana-Farber Cancer Institute in Boston. "On the one hand, we are aware of the possibility of over-treatment. On the other hand, there are still 40,000 women every year who die of breast cancer."

Perhaps some of the over-treatment can be mitigated by a new wave of tests that more accurately predict how tumors will behave based on their genetic profile. The most commonly used test is Oncotype DX, developed by Genomic Health Inc., which analyzes 21 genes to determine how likely the cancer is to recur over the next ten years. The test can also estimate whether the patient would benefit from chemotherapy, as well as radiation and surgery. Company officials say that Oncotype DX has reduced the number of U.S. breast-cancer patients on chemotherapy by 20 percent since it became available in 2004.

Though many doctors still believe that mass-screening is the best route to take, ACSH's Dr. Gilbert Ross doesn t think that over-diagnosis should be ignored. It is a quickly growing problem in the U.S., he says, causing unnecessary diagnoses that not only lead to excess anxiety and stress, but also unnecessary painful medical procedures, such as biopsies and surgeries.