FDA OKs genetic breast cancer test

Washington -- The U.S. Food and Drug Administration said it's approved a genetic test for determining if breast cancer patients should be treated with the drug Herceptin.

The SPOT-Light HER2 CISH kit is a test that measures the number of copies of the HER2 gene in tumor tissue. That gene regulates the growth of cancer cells.

A healthy breast cell has two copies of the HER2 gene, which regulates how cells grow, divide and make repairs. The FDA said patients with breast cancer might have more copies of the HER2 gene, prompting them to overproduce HER2 protein so that more signals are sent to breast cells. As a result, the cells grow and divide much too quickly.

"The SPOT-Light test counts the number of HER2 genes in a small sample of removed tumor," the FDA said. "The removed piece is stained with a chemical that causes any HER2 genes in the sample to change color."

Officials said the color change can be seen by a standard microscope, eliminating the need for the more expensive and complex fluorescent microscopes.

SPOT-Light is manufactured by the Invitrogen Corp. of Carlsbad, Calif. Herceptin is manufactured by Genentech of San Francisco.

Copyright 2008 by United Press International.