What is a PSMA scan?
"PSMA" stands for Prostate Specific Membrane Antigen, a protein found on the surface of prostate cancer cells.
A PSMA PET (positron emission tomography) scan is a type of medical imaging test that uses a radioactive tracer to produce detailed 3D images of the inside of the body.
A PSMA PET scan uses a radioactive tracer that is made to bind to the PSMA protein. Prostate cancer cells have a lot of this protein. After injecting the tracer into the patient and doing a PET scan, doctors can see where the tracer has gathered in the body. This lets them know if there are any areas of abnormal PSMA expression, which could mean the patient has prostate cancer.
A PSMA PET scan can provide valuable information for prostate cancer diagnosis, staging, and treatment planning. It is beneficial for detecting the spread of prostate cancer to other parts of the body, such as the bones, lymph nodes, and liver.
What is the imaging agent used for?
For a PSMA Pet CT, the radioactive agent is 68Ga PSMA-11.
How does it work?
Prostate cancer cells overexpress the PSMA protein. The radioactive imaging agent has a great affinity for these proteins and binds to them, pinpointing the prostate cancer location(s). It picks up significantly more prostate lesions.
How good is it at finding prostate cancer?
PSMA PET CT scan, compared to conventional imaging (CT scans, bone scans, MRIs), is better.
The PSMA PET imaging method has been shown in clinical trials to be very good at finding a lot more prostate lesions, with success rates ranging from 85% to 95%. This new imaging technique more accurately detects prostate cancer patients with early biochemical recurrence or those initially diagnosed with high-risk disease, allowing better treatment planning.
Is PSMA PET CT safe?
PSMA PET CT is considered safe for most patients, but like all medical investigations, it does carry some risks or side effects.
The tracer used in a PSMA PET/CT scan is a small amount of radioactive material, which can expose the patient to a low level of ionising radiation. This amount of radiation is typically minimal and considered safe for most patients.
There may also be minor side effects from the tracer injection, such as mild pain or swelling at the injection site and some mild discomfort or tiredness for a few hours after the scan.
Overall, the benefits of a PSMA PET CT scan outweigh the risks, and it is considered a safe and effective imaging test for detecting and managing prostate cancer.
It is always a good idea to discuss the risks and benefits of the test with your NHS prostate consultant, private urologist, or radiation oncologist to determine if it is the best option for you.
'PSMA PET CT Scan is a breakthrough technology in diagnostics for prostate cancer treatment'.
Is PSMA scan better than a Fluciclovine PET scan?
Imaging with PSMA PET CT Scan was found to significantly detect more prostate cancer than Fluciclovine PET in men who had undergone a radical prostate removal but had a recurrence of their disease.
The choice between a PSMA PET CT scan and a Fluciclovine PET scan depends on several factors, including the patient's specific clinical situation and the goals of the imaging test.
PSMA and Fluciclovine are radioactive tracers used in PET imaging to detect and manage prostate cancer. PSMA is a protein highly expressed in prostate cancer cells, while Fluciclovine is a synthetic amino acid taken up by cancer cells.
PSMA scans are highly effective in detecting prostate cancer, especially in the early stages and cases where the cancer has spread to other body parts. PSMA scans can provide detailed images of the location and extent of cancer, which can be helpful for treatment planning and monitoring the effectiveness of treatment.
Fluciclovine scans are also used for the detection and management of prostate cancer. These scans are beneficial for detecting recurrent prostate cancer after initial treatment and for monitoring the effectiveness of treatment. Fluciclovine scans may also detect prostate cancer that has spread to other body parts, although they are not as sensitive as PSMA scans.
Choosing between a PSMA scan and a Fluciclovine scan will depend on many factors. Discussing the options with your doctor to determine the best approach for your specific needs is essential.
When is a PSMA PET scan indicated?
- Diagnosis of prostate cancer: PSMA PET CT scans can help confirm the presence of prostate cancer, especially in cases where the results of other imaging tests (such as CT scans or MRI scans) are inconclusive.
- Staging of prostate cancer: PSMA PET CT scans can determine the extent of prostate cancer and help stage the disease, especially in high-risk patients. This information is essential for making decisions about treatment options.
- Detection of recurrent prostate cancer: PSMA PET CT scans can help detect prostate cancer that has returned after initial treatment.
- Monitoring the effectiveness of treatment: PSMA PET CT scans can monitor the response to treatment, including surgery, hormone therapy, and radiation therapy.
- Detection of prostate cancer spread to other parts of the body: PSMA PET CT scans can help detect prostate cancer that has spread to the bones, lymph nodes, and other organs. This information can be used to make decisions about further treatment.
- Assessing the need for biopsy: In some cases, a PSMA scan may be used to help determine if a biopsy is necessary and to guide the placement of the biopsy needle.
At what prostate-specific antigen (PSA) should I get a PSMA PET scan?
The utility of PSMA pet scans generally increases as PSA levels rise.
PSMA PET CT scans are effective at PSA levels above 0.2 ng/mL in those who have had prostate cancer treatment.
Does a negative scan mean there is no cancer?
A negative PSMA PET scan does not necessarily mean there is no cancer.
While PSMA PET CT scans offer more precise detection, they are not 100% reliable. There is always a slight chance of false negative results, which means the scan could show no cancer when cancer is present.
There are several reasons why a PSMA PET scan may show a false negative result:
- Low tracer uptake: Cancer cells may not be seen on the scan if the cancer cells do not take up enough of the radioactive tracer used in the PSMA PET scan. Or else the prostate cancer cells do not generate enough PSMA.
- Early-stage cancer: PSMA PET scans are more sensitive to detecting cancer that has progressed and spread, so early-stage prostate cancer may not be seen on the scan.
- Size of cancer: PSMA PET scans may not be able to detect minimal cancers.
Additional tests or follow-up exams may be necessary to confirm the presence or absence of prostate cancer, for example, with a biopsy in the area(s) in question.
How is a PSMA PET Scan done?
- A cannula is introduced in one of the veins of your hands.
- A radioactive tracer drug (68Ga-PSMA-11) is injected.
- The patient waits one hour.
- You will be asked to empty the bladder
- .You will lie on a unique table that moves in and out of a polo-shaped PET CT machine.
- The PSMA PET scan takes around 30 minutes.
- The entire PSMA PET scan procedure takes around 90 minutes.
How do I need to prepare before the scan?
In simple terms, there is no preparation to be done. Unlike other tests, there is no need to starve or not drink. You can take all your usual medications.
However, if you are experiencing any acute chest illness, whether COVID- or non-COVID-related, inform the center where you will have your PSMA pet scan.
What precautions should be taken after a PET PSMA scan?
Drink plenty of fluid to flush the radioactive tracer from your body.
Since you will be slightly radioactive, avoid close contact with pregnant women, babies, or young children for 24 hours. This may vary depending on the radioactive agent used. Consult with the center where the PET scan is performed.
'PSMA PET offers more precise detection and better planning.'
What is Lutetium PSMA therapy?
Lutetium-177 PSMA is an ingenious 'seek and destroy' therapy used to treat castration-resistant prostate cancer that has spread. This treatment should always be part of clinical trials.
Prostate cancer cells express more PSMA naturally. When the Lutetium-177 PSMA ligand is introduced, it will travel to those areas where the PSMA is abundant. This is attached to the prostate cancer cells and emits radiation that will destroy the cancer cells with very little radiation exposure to other parts of the body.
'The drug delivers radiation inside the body.'
Who is eligible for Lutetium PSMA targeted care?
In prostate cancer patients whose prostate cancer progressed during treatment with chemotherapy and novel hormonal therapies.
This treatment is most effective in patients whose prostate cancer expresses a very high level of PSMA expression detected on a PSMA PET scan.
If the PSMA PET scan shows that a patient's prostate cancer expresses minimal to no PSMA, Lu-177 PSMA is not indicated.
Where in the UK can I access Lutetium PSMA therapy?
Lutetium PSMA therapy is currently not widely available in the United Kingdom and is offered as part of clinical trials.
The Royal Marsden is one of the centres in the UK that offers PSMA therapy.
What are the common side effects of such a treatment?
- dry mouth,
- tiredness
- possible reduction of blood cell production
- headache
- taste change
Is this a day-case procedure?
The treatment is usually given as a day case, or a one-night stay is recommended in certain situations.
After the procedure, you can go home and resume your activities; however, always follow the recommendations of your radiation oncologists.
