Snapshot. Almost always acinar adenocarcinoma. Everything follows from the RISK GROUP — built from PSA (prostate-specific antigen), ISUP grade group (1–5) (International Society of Urological Pathology; GG1 = Gleason 6, GG2 = 3+4, GG3 = 4+3, GG4 = Gleason 8, GG5 = Gleason 9–10), and T-stage. Often indolent — many die with it, not of it — so over-treatment is a real harm, and the risk group is what protects against it. Androgen-driven → ADT (androgen-deprivation therapy) is the backbone of advanced disease.

PSA + digital rectal examination (PSA band + clinical T-stage) · multiparametric MRI → TARGETED biopsy (grade group, number/% positive cores — needed to split favourable from unfavourable intermediate) · staging imaging — PSMA-PET (prostate-specific membrane antigen, markedly more sensitive) or bone scan + CT, for nodal/distant disease and biochemical-recurrence workup · germline + somatic testing — ALL metastatic disease (HRR/BRCA1-2/ATM/CHEK2 → PARP eligibility; MMR/MSI → IO eligibility — commonly missed) · disease VOLUME if metastatic (HIGH = ≥4 bone mets with ≥1 outside the axial skeleton, OR visceral mets — decides doublet vs triplet and whether prostate RT helps).

GLEASON SCORE — read it like this: under the microscope the cancer's growth pattern is graded 3 to 5 (3 = still looks most like a normal gland; 5 = most abnormal / aggressive — patterns 1–2 are no longer used). A tumour usually shows more than one pattern, so the pathologist takes the two commonest and ADDS them — the most common one FIRST + the next = the score (e.g. 3+4=7). So scores run from 6 (=3+3) to 10 (=5+5).
The ORDER matters: 3+4=7 = mostly the milder pattern → better; 4+3=7 = mostly the aggressive pattern → worse. Same total, different prognosis.
Then it's simplified into ISUP GRADE GROUPS 1–5 (cleaner buckets, 1 = least → 5 = most aggressive): GG1 = Gleason 6 · GG2 = 3+4 · GG3 = 4+3 · GG4 = 8 · GG5 = 9–10.
cT-STAGE (clinical — by DRE ± MRI, before surgery): cT1 = not palpable or visible (found incidentally, or on biopsy for a raised PSA) · cT2 = palpable but organ-confined (a = ≤ half of one lobe · b = > half of one lobe · c = both lobes) · cT3 = beyond the capsule (a = extracapsular extension · b = seminal-vesicle invasion) · cT4 = invades adjacent organs (bladder, rectum, pelvic wall). ("c" = CLINICAL stage by exam/imaging; "p" = pathological, after prostatectomy.)
RISK GROUP (D'Amico → NCCN) — built from PSA + grade group + cT-stage (+ % positive cores splits the intermediate tier):
• LOW — PSA <10 AND GG1 AND ≤cT2a.
• INTERMEDIATE — PSA 10–20, OR GG2–3, OR cT2b–c → favourable (1 factor · GG1–2 · <50% cores) vs unfavourable (2–3 factors · OR GG3 · OR ≥50% cores).
• HIGH — PSA >20, OR GG4–5, OR cT3a.
• VERY-HIGH — cT3b–T4, OR primary Gleason pattern 5, OR >4 cores GG4–5, OR ≥2 high-risk features.
NODE-POSITIVE (N1) or metastatic (M1) sit ABOVE this ladder — automatically high-risk / advanced regardless of PSA (e.g. P43: low PSA but PSMA-positive pelvic nodes → N1 → treated as high-risk).

PSA is the readout — schedule by risk and treatment. Post-prostatectomy PSA should be undetectable; post-radiotherapy, follow the nadir (rise ≥2 ng/mL above nadir defines biochemical failure). Testosterone alongside PSA in anyone on ADT — a rising PSA is only interpretable against a confirmed castrate testosterone. Bone density (DEXA) at baseline and periodically on ADT.