Reading the PSA, finding the cancer
PSA is organ-specific, not cancer-specific — it rises with cancer, BPH, infection, and a recent ride on a bicycle. The modern pathway threads an MRI between the blood test and the biopsy so we stop finding cancers that were never going to matter.
The one-liner
PSA is a prostate signal, not a cancer test — interpret it in context and share the screening decision. mpMRI now comes before biopsy: PI-RADS 1–2 may avoid it; 3–5 gets targeted ± systematic cores. Gleason becomes ISUP grade group 1–5, and that grade drives everything downstream.
The prostate-specific antigen is one of the most useful and most misunderstood numbers in medicine. It is specific to the prostate, not to cancer — a serine protease that liquefies semen, leaking into the blood whenever the gland is large, inflamed, infected, recently instrumented, or, yes, malignant. Reading it well means holding all of those possibilities at once, and the modern diagnostic pathway is built around not over-reacting to it.
What moves the number
PSA rises with cancer, but also with BPH (more gland, more antigen), prostatitis or UTI, recent ejaculation, catheterization, or a long bike ride, and any instrumentation. A 5-α-reductase inhibitor cuts it roughly in half. So a single elevated value is a prompt to think, not a diagnosis — repeat it, treat an infection if present, and put it in context before acting.
What everyone gets wrong
Treating screening as an order rather than a conversation. PSA screening is a shared decision: it reduces prostate-cancer mortality but at the cost of overdiagnosis — detecting indolent disease that would never have caused harm. The discussion is generally offered around age 50–70, earlier (40–45) for higher-risk men: Black men and those with a strong family history or known BRCA2. The point is to find the lethal cancers without turning every man into a patient.
The pathway, in order
- PSA + DRE, interpreted in context, repeated if borderline.
- mpMRI before biopsy — the change that reshaped the field. Multiparametric MRI maps suspicious areas and is scored PI-RADS 1–5.
- Biopsy decision driven by the MRI:
- PI-RADS 1–2 with low clinical suspicion — biopsy may reasonably be deferred.
- PI-RADS 3–5 — targeted biopsy of the lesion, usually with systematic cores alongside.
The MRI’s real gift isn’t finding more cancer — it’s giving some men a credible reason to skip the biopsy, and steering the needle toward the lesions that actually matter.
How we take the cores
The route is shifting from transrectal toward transperineal biopsy, which crosses sterile skin rather than rectal mucosa and so carries a markedly lower risk of sepsis — increasingly the default as antibiotic resistance makes post-TRUS infection more dangerous.
From Gleason to grade group
The pathologist grades the two most common architectural patterns and sums them — the Gleason score — but modern reporting translates that into the cleaner ISUP grade group 1–5:
- Grade group 1 — Gleason 3+3 = 6 (the most indolent; many are watched, not treated)
- Grade group 2 — 3+4 = 7
- Grade group 3 — 4+3 = 7 (the 4-predominant 7 is meaningfully worse than the 3-predominant one)
- Grade group 4 — 8
- Grade group 5— 9–10
That grade, with the PSA and the clinical stage, sorts men into risk groups and drives every downstream decision — surveillance, surgery, radiation, the lot.
Staging the ones that need it
Most newly diagnosed cancers need no scans. For higher-risk disease, the imaging has moved: PSMA-PET now outperforms the old CT-plus-bone-scan combination for detecting nodal and metastatic spread, picking up disease that conventional imaging misses.
If you remember one thing
PSA is a prostate signal, not a verdict. Interpret it in context, make screening a shared choice, let the MRI decide who really needs a needle, and remember that the grade — ISUP 1 through 5 — is the number that tells you whether you are looking at a cancer to watch or a cancer to treat.