TUESDAY, July 8 (HealthDay News) -- The U.S. Food and Drug Administration has approved a genetic test designed to evaluate whether a person with breast cancer is a good candidate for treatment with the drug Herceptin (trastuzumab).

The SPOT-Light HER2 CISH test measures how many copies of the HER2 gene are in breast tumor cells. People with breast cancer may have more than the normal two copies of this gene in each breast cell, which can cause overactive cell growth and division.

Breast cancer patients with too many copies of the HER2 gene and overproduction of a corresponding protein are typically treated with Herceptin.

The test was evaluated during clinical trials in the United States and Finland, using tumor samples from breast cancer patients. It's produced by Invitrogen Corp. of Carlsbad, Calif.

More information

The FDA has more about this approval.