Blood test for prostate cancer

Researchers at the University of Michigan Comprehensive Cancer Center have identified a panel of 22 biomarkers that together provide a more accurate screening for prostrate cancer than the current prostrate specific antigen, or PSA, test.

Researchers looked at blood samples taken from 331 prostrate cancer patients prior to surgery, and from 159 control males with no history of cancer. They began by testing the samples against a library of 2300 bacteriophage, organisms that express proteins on their surface, and were able to narrow the field to the 22 biomarkers that most often pinpointed the cancerous blood samples.

The results proved to be more reliable at predicting cancer than prostrate specific antigen, which is a single biomarker. PSA testing results in a false positive around 80% of the time, leading to unnecessary prostrate biopsies. The normal range for the PSA test is less than 4.0 (ng/mL) in most men. For men over 40 years old with a family history of prostrate disease or for African-American men over 40 years old, some doctors suggest that a level higher than 2.5 ng/mL should be checked with more tests, because these two groups of men have an increased risk of prostrate cancer.

The 22-biomarker test was reliable at identifying prostrate cancer even in the PSA ranges of 4-10 ng/mL or 2.5-10 ng/mL, intermediate PSA scores that do not always suggest cancer. The study authors suggest the 22 biomarkers could be used for patients in this range to help determine whether to undergo a biopsy.

The new test requires only a routine blood draw for patients. Most blood-processing laboratories could easily be equipped to scan for these 22 biomarkers. Researchers are conducting further studies to validate the findings with a large, community-based group of patients.