BACKGROUND: In the first clinical study of a new blood protein associated with prostate cancer, researchers have found that the marker EPCA, or early prostate cancer antigen, can successfully detect prostate cancer in its earliest stages. The current technique for detecting prostate cancer prostate-specific antigen (PSA) testing, can sometimes indicate cancer when none is there. Prostate cancer is the most common type affecting American men, with about 232,090 new cases diagnosed in 2005.
WHAT IS THE PROSTATE: The prostate is a walnut-sized gland, located between the bladder and the penis and in front of the rectum. Its primary function is the production of seminal fluid, the milky substance that nourishes sperm.
WHAT IS PSA TESTING: PSA testing is one step in early identification of prostate tumors, combined with digital rectal examination. But PSA testing can miss some cancers, or produce a false positive (indicate a cancer that doesn't exist). Furthermore, a prostate biopsy is a very painful and unpleasant procedure, with 12 separate tissue extractions followed by a month of pain. The biopsy usually needs to be repeated each year after the first positive PSA result, even if the initial biopsy comes out negative. Of the 1.8 million biopsies performed annually, only 15 percent come out negative. Reducing the number of biopsies requires for an accurate diagnosis would bring welcome relief to many patients.
NEW BLOOD TEST: Researchers at Johns Hopkins measured the ECPA levels in 46 patients, including those with prostate cancer, bladder, colon and kidney cancer, spinal cord injury, and noncancerous prostate inflammation, as well as 16 healthy individuals. They found that EPCA levels were high in 11 of the 12 prostate cancer patients and low in all the healthy individuals. They estimate an accurate diagnosis rate of 94 percent. When coupled with standard PSA screening, the new blood test could help reduce the number of unnecessary biopsies and undetected prostate tumors. The ECPA test very specific to prostate cancer; it doesn't indicate other types of cancer or benign prostate conditions.
WHEN AVAILABLE: Larger clinical trials will be starting soon, and it is believed that the blood test will be generally available to medical practitioners in 2006.