Prostate-specific antigen testing: Improving accurate risk assessment for high-grade prostate cancer

Although the prostate-specific antigen (PSA) test remains a valuable tool in detecting prostate cancer, its use as a routine screening method continues to generate debate. PSA levels can rise for many noncancerous reasons—such as benign prostatic hyperplasia (BPH), prostatitis, or even recent prostate manipulation—and can be artificially lowered by certain medications or obesity. This lack of specificity makes test results difficult to interpret, can lead to false positives and unnecessary biopsies, and can result in overdiagnosis of slow-growing cancers that may never cause harm. In turn, some men undergo overtreatment, exposing them to potential complications that may outweigh the actual risk posed by the cancer itself.¹

By adding tests that are more specific than PSA for high-grade cancer to the diagnostic process, healthcare providers can better stratify risk, enhance decision-making, and improve overall patient management. One of these tests is IsoPSA^®, which helps to more accurately identify patient risk for high-grade prostate cancer than PSA testing.²

In this article:

Clinical challenge | Why it matters | Ordering recommendations | Interpreting test results | Next steps | Supporting resources

Clinical challenge: Standard screening with unclear implications

For men in the US, prostate cancer is the second leading cause of cancer death. However, most patients diagnosed with it don’t die from prostate cancer. In fact, according to the American Cancer Society, more than 3.5 million of those diagnosed with prostate cancer at some point in the US are still alive today.³

Due to the relatively slow progression of the disease, current guidelines for PSA testing are not always clear.

Why it matters: Incomplete information can increase risks in some cases

Screening results that show elevated PSA levels can often lead providers and patients to opt for a prostate biopsy, which brings the risks of pain, blood in the semen or ejaculate, and infection.

Screening can also identify potential prostate cancer and lead to treatment—and complications—in some patients who would not have experienced symptoms or died from the disease.⁵ Finding ways to add more clarity to the diagnostic picture can help to reduce this type of overdiagnosis and its attendant negative outcomes.

IsoPSA^®: A blood test that more accurately detects high‑grade prostate cancer⁵

The IsoPSA^® blood test helps determine if elevated PSA came from cancer cells. Compared to the standard concentration-based PSA test, IsoPSA analyzes the structure of the PSA protein, providing more biological certainty around whether an elevated PSA is due to cancer.

Ordering recommendations: IsoPSA helps determine if elevated PSA came from cancer cells

Quest Diagnostics offers IsoPSA, a blood test for men with elevated PSA that more accurately detects high-grade prostate cancer and aids in clinical decision-making.

Recommended test: IsoPSA^®

• Test code: 12061
• CPT code: 0359U

Clinical Significance

IsoPSA is a structure-based (rather than concentration-based) assay that interrogates the entire spectrum of structural changes to PSA (or isoforms) and can effectively differentiate between high-grade prostate cancer and low-grade prostate cancer/benign.

The CPT codes provided are based on American Medical Association guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

Testing considerations:

Do not collect specimens under the following circumstances

• Within 72 hours after prostate manipulation, including DRE.
• Within 2 weeks after UTI and/or prostatitis.
• Within 30 days after prostate surgery, including prostate biopsy, urinary catheterization, prostate infarction, or endoscopic evaluation, or other urinary tract malignancy after a transrectal biopsy.

Interpreting test results

Predicting longitudinal risk for csPCa⁶

Next steps:

If you would like to learn more about IsoPSA and how it can benefit your practice, please reach out to your sales representative or visit https://www.questdiagnostics.com/healthcare-professionals/about-our-tests/cancer/prostate

Supporting resources