The biggest risk for breast cancer patients is usually not original tumor, which is removed by surgery. The cancer becomes particularly deadly if it metastasizes and forms tumors elsewhere in the body.

But drugs to target the metastatic process would fail the current clinical-trial system for breast cancer treatments.

Patricia Steeg is the chief of the Women’s Cancers Section at the National Cancer Institute. She argues in the journal Nature that a new approach is needed in testing and approving breast cancer drugs. [Patricia S. Steeg, "Perspective: The right trials"]

New breast cancer drugs today must demonstrate that they shrink established tumors. But a beneficial drug might not reduce the size of a tumor. Instead, it might fight metastasis in a number of ways—it could kill keep cells from escaping the tumor, or kill them in the bloodstream.

Steeg argues that the FDA needs to change the model, and that anti-metastasis drugs should be tested in combination with current therapies. The success should not be related only to shrinking tumors, but rather to preventing new tumors from forming. She says this approach will help not only breast cancer patients, but millions of survivors in remission who worry that a new tumor will appear.

—Cynthia Graber

[The above text is a transcript of this podcast.] 

[Scientific American is part of the Nature Publishing Group.]