A simple blood test costing as little as $25 may be able to detect cancer in its early stages, based on results of a preliminary study involving a small number of patients.

If larger studies show the test is accurate, it may mean cancer could be detected during annual physical examinations before any physical symptoms are present, biochemist Stuart Gordon said Wednesday.In a study involving 271 cancer patients published in the journal Cancer Research, the test was 100 percent effective in identifying a protein shed by cancer cells in the early stages of the cancer. The test was only 76 percent effective in detecting late-stage cancers.

"This is too small a study to make any absolute statement, but it's enough to make us procede," said Gordon, an associate professor at the University of Colorado School of Medicine.