Oct. 23 (Bloomberg) -- Genomic Health Inc., the maker of a genetic test to predict breast cancer relapse, gained the most since January in Nasdaq trading after the largest U.S. group of cancer doctors recommended its product.

Genomic Health, based in Redwood City, California climbed $3.28, or 16 percent, to $23.89 at 4 p.m. New York time in Nasdaq Stock Market composite trading. It rose 18 percent Jan. 10 after UnitedHealth Group Inc., the largest U.S. health insurer, agreed to cover the test.

The product, Oncotype DX, was recommended in guidelines written by the American Society of Clinical Oncology. The test, which costs $3,460 a patient, was first introduced in January 2004. Studies have shown it can help women avoid unnecessary chemotherapy when their DNA profile shows they are at a low risk of relapse. The company has said it expects sales of $57 million to $63 million this year.

``While exciting research and multiple prognostic tools are available today, Oncotype DX is the only genomic test that has sufficient clinical evidence to support its use in clinical practice,'' said Gabriel Hortobagyi, a breast cancer specialist at the University of Texas M.D. Anderson Cancer Center in Houston, in a company statement.

To contact the reporter on this story: Luke Timmerman in San Francisco at ltimmerman@bloomberg.net

Last Updated: October 23, 2007 16:20 EDT