Prostate cancer — staging and biochemical recurrence

EAU prostate cancer guideline; NCCN prostate cancer (staging by risk group); EANM PSMA PET procedure guidelines

Once cancer is proven, the questions are whether disease has left the prostate and, after treatment, where a rising PSA is coming from. PSMA PET-CT answers both more accurately than the conventional bone scan and CT combination, and does so at PSA levels where conventional imaging is blank.

Biopsy-proven prostate cancer requiring staging before radical treatment, or a confirmed PSA rise after prostatectomy or radiotherapy.

Referenced decision support — confirm against your local protocol.

Decision support, not a directive. Protocols and timings shown are typical published ones — your local protocol takes precedence, and the vetting radiologist decides.

The request in front of you

Everything is optional. Leave a field alone and the answer assumes nothing — the verdict updates as you go.

Study requested

What the referrer actually asked for. It is evidence of intent, not a constraint on the right answer.

Contrast as written

What the request form says, not what it should say.

Age

Pick a band, or type an exact age if it matters.

years

Pregnancy status

Renal risk factors

The question a vetter can actually answer from the request. An explicit “none known” is a real answer, and it removes checks rather than deferring them.

Previous contrast reaction

The pathway — tap anything already done

Marking a study complete moves the answer on. A patient arrives partway through a pathway far more often than at the start of one.

Accept as requested

PSMA PET-CT

What we'd amend, and why

Two conditions have to hold before any of the biology below is worth anything: the cancer is proven on tissue, and the risk group justifies staging at all. This study belongs to unfavourable intermediate and high-risk disease. Grade group 1 with a PSA under 10 and clinically organ-confined disease is not staged — the yield is close to zero and the positives are mostly false — so the correct answer to a staging request in that patient is that imaging is not indicated, and saying so is the more useful vetting act. With that established: prostate-specific membrane antigen is expressed on the tumour cell surface and increases with dedifferentiation, so the tracer marks disease by biology rather than by size or osteoblastic reaction. That is why it finds nodal deposits below the size threshold that makes a node abnormal on CT, and skeletal disease before there is enough bone turnover for a diphosphonate scan to show anything. In the recurrent setting its detection rate at low PSA is what makes salvage treatment targeted rather than empirical.

Nothing needs resolving before this goes ahead. Routine checks below are owned downstream.

How was this decided?

pathwaystandard — Adults — staging and recurrence
rulerule-pregnancy-ionising — Pregnancy status before an ionising exposure; checked by Radiographer at the scanner

Decision support only. Local protocol takes precedence.

Handled at the scanner(1)nothing for you to do

Settled and owned downstream. Each returns to a radiologist only on the stated trigger.

Pregnancy status before an ionising exposure
Make the pregnancy enquiry immediately before the exposure and record the answer. In the UK this is a statutory operator duty discharged at the time of exposure under the employer’s written procedures required by IR(ME)R 2017 — it is not something the vetting radiologist can perform or pre-empt, and a request is complete without it.
Radiographer at the scannerAt the scanner
Flags back if: The patient states that she is, or may be, pregnant AND the uterus is in or near the primary beam. The exposure is then paused for re-justification by the IR(ME)R practitioner before it proceeds.

Worth asking the referrer (2)

None of these hold the request up. They sharpen the protocol or the plan that follows.

What is the risk group — PSA, ISUP grade group (Gleason score) and clinical T stage?
It decides whether staging imaging is indicated at all, not merely which study. Low-risk localised disease is not staged: the yield is near zero, so most positives are false, and a false positive costs the patient more than the information is worth.
For a suspected recurrence — what is the current PSA, the post-treatment nadir, the doubling time, and what treatment was given?
Detection rate on PSMA PET rises steeply with PSA and with a short doubling time. Below about 0.2 ng/mL after prostatectomy a negative scan is expected and changes nothing, so the study adds delay rather than information.

Pathways

Big forks are separate pathways; the first whose conditions match is the one used.

Adults — staging and recurrence

Matches your inputsDefault

Role	Study & protocol	Why this answers the question
First line	PSMA PET-CT PSMA PET-CT usually appropriate	Two conditions have to hold before any of the biology below is worth anything: the cancer is proven on tissue, and the risk group justifies staging at all. This study belongs to unfavourable intermediate and high-risk disease. Grade group 1 with a PSA under 10 and clinically organ-confined disease is not staged — the yield is close to zero and the positives are mostly false — so the correct answer to a staging request in that patient is that imaging is not indicated, and saying so is the more useful vetting act. With that established: prostate-specific membrane antigen is expressed on the tumour cell surface and increases with dedifferentiation, so the tracer marks disease by biology rather than by size or osteoblastic reaction. That is why it finds nodal deposits below the size threshold that makes a node abnormal on CT, and skeletal disease before there is enough bone turnover for a diphosphonate scan to show anything. In the recurrent setting its detection rate at low PSA is what makes salvage treatment targeted rather than empirical.
First line	MRI Prostate MRI Prostate — multiparametric (PI-RADS)	Local staging is a separate question that PET does not answer. Extraprostatic extension, seminal vesicle invasion and the relationship to the neurovascular bundles determine the surgical plan and are resolved on high-resolution T2 with a small field of view.
Second line	Bone scintigraphy Bone scintigraphy — whole body (± three phase)	The conventional skeletal survey, still appropriate where PSMA PET is unavailable and in the many services where access is rationed. It is less sensitive at low disease burden and less specific in a degenerate elderly skeleton, so a solitary equivocal focus usually needs anatomical correlation before it changes anything.
Reasonable alternative	Whole-Body MRI Whole-Body MRI — metastatic disease and cancer predisposition surveillance	Diffusion-based whole-body MRI is the alternative for bone-dominant disease and for serial assessment of skeletal burden on treatment, where response is being judged rather than presence, and where cumulative radiation from repeated CT and scintigraphy is a genuine consideration.

Pitfalls

Staging low-risk localised prostate cancer. ISUP grade group 1 with a PSA under 10 and cT1-2a disease gets no PSMA PET, no bone scan and no staging CT — the yield is near zero, so what the scan mostly produces is a false positive, a delay and a patient who is now being treated for something they do not have.
Vetting a staging request that states neither PSA nor grade group nor clinical stage. Those three numbers decide whether the study is indicated at all, and asking for them is a better use of the vetting call than protocolling the scan.
Requesting PSMA PET before any tissue diagnosis. It is a staging and localisation tool, not a detection test for a raised PSA.
Reading uptake in coeliac or cervical ganglia as nodal metastasis — a well-described trap resolved by looking at the CT component.
Assuming a negative scan excludes recurrence and withholding salvage radiotherapy on that basis.
Using PET to answer a local staging question that needs MRI.
Imaging at a very low PSA where the detection rate is low and a negative result changes nothing, so the scan adds delay rather than information.

Priors — what to pull first

The PSA trajectory, not a single value, is what makes the imaging interpretable — record the nadir, the doubling time and the treatment history.
Where a previous PSMA study exists, the same tracer and the same uptake time should be used; detection rates and uptake patterns differ between agents.

What makes a good request

Low-risk localised disease is not staged with imaging at all, and that is the first question this card asks. Both European and North American guidance advise against cross-sectional and skeletal staging in ISUP grade group 1 disease with PSA under 10 ng/mL and cT1-2a: the yield approaches zero, so the great majority of positives are false, and each one costs the patient a further test, a delay, or a treatment they did not need. Staging imaging belongs to unfavourable intermediate and high-risk disease — ISUP grade group 3 or above, PSA above 20, or cT3 and beyond. A staging request that does not state PSA, grade group and clinical stage is a request that cannot be vetted, and asking for those three numbers is more useful than protocolling the scan well.
The threshold for imaging biochemical recurrence is a decision about consequences, not just about PSA: European guidance recommends PSMA PET-CT when PSA exceeds about 0.2 ng/mL after prostatectomy and when the result will change the treatment plan.
A negative PSMA PET does not exclude disease and should not delay salvage radiotherapy that is otherwise indicated.
PSMA is expressed in benign tissue too — coeliac and cervical ganglia, some healing fractures, Paget disease — so the CT component is not an accessory, it is how false positives are excluded.
Local T-staging remains an MRI question. PET localises disease; it does not resolve extraprostatic extension or seminal vesicle invasion.

Scoring this once it is done

The classification and risk tools this question ends in.

PROMISE Criteria / miTNM Staging (PSMA-PET)PSMA-RADS 1.0 PI-RADS v2.1 (Prostate MRI)Pluvicto Dose Modification for Adverse Reactions Prostate Volume & PSA Density

How these studies are acquired

Contrast, phases and timing for every study on the pathways above.

PSMA PET-CT MRI Prostate — multiparametric (PI-RADS)Bone scintigraphy — whole body (± three phase)Whole-Body MRI — metastatic disease and cancer predisposition surveillance

Confirm locally

PSMA PET-CT: timings are typical — confirm against local protocol.
Timings, contrast volumes and rates above are typical published values. Your department's protocol, scanner and patient population decide the actual numbers.
Safety thresholds and premedication policy follow local policy where it differs from the cited guidance.

References

Implemented from the cited published sources. Educational and workflow support only; confirm against current guidelines and local policy before clinical use.