PSMA PET Scan for Prostate Cancer
PSMA PET imaging has transformed how prostate cancer is staged and managed. It allows more accurate detection of cancer spread than conventional imaging and plays an increasingly important role in treatment planning.
Mr Philip Dundee is a Melbourne-based urological oncologist who integrates PSMA PET imaging into prostate cancer decision-making. He has published on the use of PSMA PET in recurrent prostate cancer, including the detection of recurrence at very low PSA levels.
to discuss your diagnosis and treatment options.
What is a PSMA PET scan and when is it used?
A PSMA PET scan is an advanced imaging test used to determine whether prostate cancer has spread from the prostate to other parts of the body such as lymph nodes, bone or other organs.
The scan works by targeting prostate-specific membrane antigen (PSMA), a protein expressed on prostate cancer cells. This allows areas of prostate cancer to be identified, including disease that may not be visible on conventional imaging such as CT or bone scans.
PSMA PET is most commonly used:
- At initial diagnosis in patients with intermediate and high-risk prostate cancer
- When PSA is rising after treatment (biochemical recurrence)
- To guide treatment decisions and planning
PSMA PET is not required for all patients with prostate cancer, and its use depends on the characteristics of the cancer and the clinical situation.
CLINICAL SCENARIOS
Clinical applications of PSMA PET
The following examples demonstrate how PSMA PET imaging influences staging, treatment selection and management of recurrent prostate cancer.
Scenario 1: Localised prostate cancer
A 63 year old man has a PSA of 7.9 ng/mL and a PI-RADS 4 abnormality on MRI. His biopsy revealed ISUP Grade Group 2 (Gleason 3+4=7) prostate cancer within the MRI target. PSMA PET demonstrated an avid (“hot”) lesion within the prostate corresponding to the MRI abnormality, but no evidence of prostate cancer elsewhere in the body.
This patient’s best management option is either surgery or radiotherapy. He has localised prostate cancer and although some patients with Grade Group 2 prostate cancer are suitable for active surveillance, MRI-visible disease with a corresponding abnormality on PSMA PET indicates a higher risk of future progression without treatment.
Scenario 2: Pelvic lymph node involvement
A 67 year old man with no significant past medical history has a PSA of 14 ng/mL and MRI demonstrating a PI-RADS 5 lesion. Biopsy reveals ISUP Grade Group 4 (Gleason 4+4=8) prostate cancer. PSMA PET demonstrates an avid lesion within the prostate as well as an avid pelvic lymph node, but no evidence of disease outside the pelvis.
Although this patient’s prostate cancer has already spread to a pelvic lymph node, his disease remains confined to the pelvis and definitive local treatment with either surgery or radiotherapy remains appropriate. However, the PSMA PET findings change the treatment plan, which should now also include treatment directed at the pelvic lymph nodes in addition to the prostate.
Scenario 3: Biochemical recurrence following surgery
A 73 year old man underwent surgery for prostate cancer 6 years ago. Although his PSA was initially undetectable following surgery (<0.01 ng/mL), he has subsequently developed a biochemical recurrence and his PSA is now 0.23 ng/mL with a doubling time of 6 months. PSMA PET demonstrates a solitary pelvic lymph node recurrence with no evidence of disease elsewhere.
This patient has pelvic nodal recurrent prostate cancer. Before PSMA PET imaging became available, patients such as this were routinely treated with prostate bed radiotherapy, which carries risks of bladder and bowel side effects in the longer term. Because the site of recurrence has been identified, the patient is suitable for targeted stereotactic radiotherapy to the involved lymph node, while prostate bed radiotherapy remains available in the future should a prostate bed recurrence subsequently be detected.
Is PSMA PET better than MRI?
They provide different information. MRI assesses local disease, while PSMA PET detects prostate cancer anywhere in the body. There are an increasing number of trials assessing the use of PSMA PET in the initial diagnosis of prostate cancer, where it may be complimentary to MRI.
Can a PSMA PET scan change my treatment?
Yes. PSMA PET frequently identifies disease that is not visible on conventional imaging and may influence whether surgery, radiotherapy, surveillance or other treatments are recommended.
Do all patients need a PSMA PET scan?
No. Many patients with low-risk prostate cancer do not require PSMA PET imaging. It is most commonly used in intermediate-risk and high-risk disease, or when recurrence is suspected following treatment.
Can PSMA PET detect very small cancers?
It is highly sensitive but may not detect all areas of microscopic disease.
Book a consultation
If you are considering PSMA PET imaging or have been advised to undergo a scan, a consultation can help determine how the results will influence your treatment plan.
