Detecting Prostate Cancer: Beyond the Gloved Finger
It’s been a tough time lately for advocates of a popular blood test used to help diagnose prostate cancer. It’s called a Prostate-Specific Antigen (PSA) Test. First, the Feds trashed the PSA test, giving it a “D” grade for prostate cancer screening. In a mea culpa response, urologists admitted that we could improve the way we used PSA and then we changed our recommendations for its use. Soon enough, publications began to emerge how PSA screening has really helped save lives over the last 30 years. It appeared that we all agree that PSA has value. Finally, seeing all this, the Feds raised PSA’s grade to a “C”, which we’ll take, thank you very much.
But what emerged from the national outcry around PSA screening was actually silk from a sow’s ear: It pushed into the clinical arena much better alternatives to PSA for prostate cancer screening. Innovative biomarker based tests are now out there that can keep men from having the nasty and expensive prostate biopsy that was triggered by a suspicious PSA blood test.
The basic problem with PSA is that things besides cancer can raise its levels: prostatitis, plain ol’ age, urologic procedures and benign prostatic enlargement can raise holy hell with PSA. Even ejaculation and bicycling are suspect when it comes to PSA elevation.
Even worse, some herbals, a daily aspirin, being overweight, taking finasteride (to prevent balding), and some cholesterol and diuretic medications can lower PSA levels, further complicating its ability to detect cancer. In other words, PSA is more of the prostate’s “weatherman” of what’s happening on all fronts than it is an accurate cancer marker. So, although better than a doctor’s gloved finger, PSA is nowhere close to being an ideal marker for prostate cancer.
Imbibed with the highly desirable goal of reducing unnecessary prostate biopsies, here’s a list of newer, more sophisticated, biomarker tests that have gained popularity since the PSA screening hoopla:
- Free and Complexed PSA. It so happens that PSA lives several different lives: one is being married to other proteins and the other is freely available. The lower the free PSA, the higher the chance of cancer. Both free as well as married or “complexed” PSA forms are now measurable.
- IsoPSA. This blood test assesses all forms of PSA in blood, including immature and mature PSA and all free and married types. It also looks at the various proteins PSA is married to in blood. And because of this, it is a more precise marker of cancer than is the PSA test.
- Prostate Cancer Gene 3 (PCA3). This looks for the prostate cancer-specific gene PCA3 in prostate cells that are shed in the urine. That means it’s a urine test. It is better than PSA because it is less of a “weather” barometer of the prostate and more of a reporter of cancer within the gland.
- 4K Score. This algorithm-based test combines a blood test of 4-prostate-specific biomarkers (including free and total PSA) with clinical history to calculate a precise risk of having aggressive prostate cancer, which is the kind you don’t want.
- Prostate Health Index (PHI). This biomarker based mathematical test (that incorporates total, free and pro-2-PSA) does a better job than PSA of predicting the presence of cancer and also aggressive prostate cancer.
Please remember that these new fangled biomarker-based tests do not actually diagnose prostate cancer. They simply help determine the risk of having prostate cancer. Still, what’s really attractive about these next gen assays is that, unlike the basic PSA test which is a tissue-specific marker, they are more cancer-specific. And that my friends, is an excellent way to get more precise information about the chance of having cancer and also allow you to avoid the not-so-fun prostate biopsy to figure this out.
Join the Tweet Chat
Come join us and learn about this and more on this month’s prostate cancer tweet chat on Friday, September 29th from noon to 1pm PT hosted by the Urology Care Foundation! Just go to follow the #KYStatsChat hashtag. I’ll be tweeting live again this year, alongside NFL Hall of Fame superstars and others who’ve been affected by prostate cancer.