Swedish scientists have discovered a new chemical marker of prostate cancer—one that could help you avoid the problems with prostate specific antigen (PSA) testing, like false positives for men with naturally high PSA levels.
The new test looks at blood levels of prostasomes, tiny particles that are pumped out by prostate cells. Researchers believe that when cancer sets in, prostasomes don’t end up in the semen like usual—they are sent to the surrounding cancer tissue (and therefore your blood) instead.

Promising Early Results
An early study found blood prostasome levels were higher in 20 patients with prostate cancer than in 20 men without the disease, researchers reported in Proceedings of the National Academy of Sciences.
“Blood levels of so-called prostasomes seem to correlate more closely with the severity of the disease than do PSA levels,” says one of the study’s authors, Masood Kamali-Moghaddam, in a press release. Meaning: The test could not only diagnose prostate cancer, but also provide doctors a clue about how advanced it is.

Problems with PSA Tests
Since 1994, there has been a declining death rate of 4 percent a year for prostate cancer—the second most common cancer in men. That decrease has been credited to the common use of PSA testing, which began in the 1990s. That’s good, right? Well, here’s the problem: An elevated PSA level doesn’t necessarily mean you have prostate cancer. Inflammation, benign prostate enlargement, age, and race can all lead to high levels of PSA. Plus, PSA values can even vary from lab to lab.
The inaccuracy in PSA testing means that many men receive wrong results, leading to unneeded operations. As many as 75 percent of men who undergo a prostate biopsy don’t actually have cancer, according to the National Cancer Institute
The prostasome test is in the early stages of development and still many years away from widespread use, but it’s a step closer to finding a way to reliably diagnose the disease.
—Jill Yaworski