The PSA Test: Prostate Cancer Screening Explained

The simple versionExplain▾

Prostate-specific antigen, or PSA, is a protein made by both normal and cancerous cells of the prostate. The PSA test measures how much PSA is in your blood. The catch: both prostate cancer and benign conditions — like an enlarged prostate (BPH) or inflammation (prostatitis) — can raise PSA. That's a big reason the test is not a simple yes-or-no for cancer.

The test is used in three main ways: to monitor people already diagnosed with prostate cancer, to follow up on prostate symptoms, and — more controversially — to screen people who have no symptoms.

Is PSA screening recommended?Explain▾

Not routinely. PSA was widely used for population screening starting in the late 1980s, but as more was learned about its harms, many organizations began cautioning against it. Today most recommend that anyone considering PSA screening first discuss the risks and benefits with their doctor.

The U.S. Preventive Services Task Force recommends:

• Ages 55–69: the decision to screen should be an individual one, made after weighing the potential benefits and harms in light of your own values.
• Age 70 and older: PSA-based screening is not recommended.

Some organizations suggest earlier routine testing (beginning at 40 or 45) for people at higher risk — including Black men, those with inherited BRCA2 (and to a lesser extent BRCA1) changes, and those whose father or brother had prostate cancer.

What counts as a "normal" resultExplain▾

There's no single cutoff that separates normal from abnormal, and no level that means cancer for sure — though higher PSA makes cancer more likely. A level above 4.0 ng/mL is generally considered abnormal and may lead to a biopsy, but doctors sometimes adjust the cutoff by age or medication. Temporary bumps can come from infection, inflammation, a recent biopsy, vigorous cycling, or ejaculation, so it's common to wait and avoid those activities before testing.

Weighing benefits and harmsExplain▾

The potential benefit is catching prostate cancer earlier, when it may be easier to treat — which can lead to a small reduction in prostate cancer deaths over about 10 years.

The harms are real and important:

• Overdiagnosis and overtreatment. Some cancers found by PSA grow so slowly they'd never cause problems, but treating them can cause urinary, bowel, and sexual side effects.
• Earlier detection doesn't always mean cure. Some tumors have already spread before they're found.
• False positives are common. About 6–7% of men have a false-positive PSA on a given screening round, and only about 25% of those biopsied for an elevated PSA actually have cancer — while biopsies carry risks of pain, bleeding, and infection.

To make this concrete, the USPSTF estimates that for every 1,000 men ages 55–69 screened for 13 years, roughly 1–2 prostate cancer deaths are avoided, while about 240 have a positive result (many false), 100 are diagnosed, and 80 are treated — many experiencing serious complications such as sexual dysfunction or urinary incontinence. This is exactly why NCI frames PSA screening as a personal decision, not an automatic one.

After a prostate cancer diagnosisExplain▾

The PSA test is also valuable after treatment. Following surgery or radiation, a rising PSA can be the first sign of recurrence — often appearing months or years before symptoms. But a single elevated reading doesn't necessarily mean the cancer is back; doctors look for a rising trend over time, sometimes with imaging, before recommending more treatment.