PSA (prostate-specific antigen) is a protein produced by both normal and cancerous prostate cells. A PSA test measures its level in nanograms per millilitre (ng/mL) of blood. It is the primary screening tool for prostate cancer but is not a cancer test — it detects an abnormality that requires further investigation, not cancer itself.
What is a normal PSA level?
PSA levels rise with age as the prostate naturally enlarges. Traditional thresholds have been set at 4.0 ng/mL, but this single cut-off is increasingly seen as too blunt. Many guidelines now use age-specific ranges, and PSA velocity (the rate of change over time) is considered alongside absolute values.
| Age group | Approximate normal PSA range |
|---|---|
| 40–49 | < 2.5 ng/mL |
| 50–59 | < 3.5 ng/mL |
| 60–69 | < 4.5 ng/mL |
| 70+ | < 6.5 ng/mL |
Why a raised PSA doesn't mean cancer
PSA is elevated in several non-cancerous conditions: benign prostatic hyperplasia (BPH) — prostate enlargement that affects most men over 50 — prostatitis (prostate inflammation or infection), recent sexual activity, vigorous exercise (particularly cycling), and urinary tract infections. PSA should not be tested within a week of a prostate biopsy or vigorous physical examination.
Roughly 75% of men who have an elevated PSA and go on to have a biopsy do not have cancer. The remaining 25% do, and some of those cancers may be slow-growing and never become life-threatening.
What happens after a raised result
- A repeat PSA to confirm the reading, as single results can fluctuate
- A free-to-total PSA ratio — a lower free PSA percentage is more associated with cancer
- MRI of the prostate (mpMRI) — now the preferred imaging before biopsy in most guidelines
- Prostate biopsy if the MRI is suspicious — guided by MRI targets (MRI-fusion biopsy)
The PSA debate and informed decision-making
PSA screening is controversial because it can detect slow-growing cancers that would never have caused symptoms or death during a man's lifetime — leading to unnecessary biopsies, anxiety and overtreatment. The USPSTF (US Preventive Services Task Force) recommends informed individual decision-making for men aged 55–69 rather than blanket screening.
Most urologists and cancer organisations recommend men discuss their individual risk (family history, ethnicity — Black men have significantly higher prostate cancer risk — and symptoms) with their doctor at age 50, or 40–45 for those at higher risk.
"A PSA result opens a conversation — it doesn't make a diagnosis. The investigation that follows is what determines the truth."
Omar Khalil, Health Educator, Looms