PSMA
What is PSMA?
PSMA stands for prostate-specific membrane antigen, a protein that sits on the surface of prostate cells. In men with prostate cancer, prostate cells produce a lot more PSMA than normal.
Because prostate cancer cells show high levels of PSMA, it has become a target for advanced imaging tests like the PSMA PET scan. The scan helps doctors find prostate cancer in your body, even if the tumors are small or located in areas other scans can’t easily detect.
Understanding PSMA Prostate Cancer and Advanced Imaging
A PSMA PET scan is a specialized imaging test. It uses a small amount of radioactive material, called a tracer, to look for prostate cancer cells. This tracer is specially designed to stick to PSMA proteins. Once injected into the body, it travels through the bloodstream and attaches to cancer cells that overexpress PSMA.
The scan uses positron emission tomography (PET), which detects the tracer. It is often combined with a CT or MRI to provide detailed pictures of your body. This combo lets your doctor see where prostate cancer is and how active it is. This gives them a more detailed overall picture than regular imaging tests.
What is the Difference between PSA and PSMA?
Prostate-specific antigen (PSA) and PSMA are both related to the prostate. However, they are distinct in terms of their roles and applications.
PSA is a protein produced by both normal and cancerous cells in the prostate. It’s commonly used as a blood test to help screen for prostate cancer and monitor the progression of the disease. Higher levels of PSA can indicate prostate cancer. It can also be due to other prostate conditions, such as benign prostatic hyperplasia (BPH) or prostatitis. PSA levels can help detect prostate cancer. However, it is not a definitive test because other conditions can also elevate PSA levels.
PSMA is a protein found on the surface of prostate cancer cells, especially in more aggressive forms of the disease. Unlike PSA, PSMA is a membrane-bound antigen. This makes it especially useful for targeting cancer cells in imaging and therapeutic approaches.
Why Would You Need a PSMA Scan?
This scan often finds prostate cancer that other imaging tests miss, especially when PSA levels are low but still increasing. Your doctor may recommend a scan if you:
- Just received a prostate cancer diagnosis, and they want to check if it has spread beyond the prostate.
- Completed treatment, but your PSA levels are rising, which might signal the cancer is returning.
- Have advanced prostate cancer and need help deciding if you qualify for specific treatments, like PSMA-targeted radioligand therapy (Pluvicto).
How Long Does a PSMA PET Scan Take?
A PSMA PET scan typically takes about 1.5 to 2 hours from start to finish.
A small amount of radioactive tracer will be injected into a vein in your arm. After the injection, you’ll wait about 45 to 60 minutes while the tracer travels through your body and attaches to any prostate cancer cells.
When it’s time for the scan, you’ll lie on a table while the scanner either moves around you or you slowly pass through it. The scan itself usually takes 20 to 40 minutes. It doesn’t hurt, but staying still for that long can be a bit uncomfortable.
Does a PSMA PET Scan Detect Other Cancers?
PSMA isn’t only found in prostate cancer. It can sometimes appear in other types of cancer, like kidney, thyroid, and breast cancer. Even though the scan may pick up PSMA in these other cancers, PSMA PET scans are only approved for use in diagnosing and managing prostate cancer. If your doctor suspects a different type of cancer, they’ll use more appropriate imaging tests.
Are PET Scans Safe?
PSMA PET scans are generally safe, and serious side effects are rare. The tracer contains a small amount of radiation that leaves your body through your urine. The radiation exposure is low and similar to many other diagnostic imaging tests.
To help flush it out faster, you will be encouraged to drink plenty of water and urinate frequently after the scan.
This scan is a highly sensitive and precise tool. If you have a new diagnosis, a recurrence, or advanced prostate cancer, this test can be very helpful for you and your doctor. It provides the information necessary to develop the most effective treatment plan for you.
PSMA FAQs
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Can I drive home after a PSMA PET scan?
The scan doesn’t involve sedation, so you’ll be able to drive yourself home unless your doctor tells you otherwise.
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What does it mean if PSMA shows up in areas outside the prostate?
If PSMA shows up in bones, lymph nodes, or organs, it may mean the prostate cancer has spread. Your doctor will interpret the scan results in the context of your medical history, overall health, and other test results.
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Can PSMA PET scans be used to see if my treatment is working?
In some cases, yes. If you’re undergoing treatment for advanced prostate cancer, your doctor might use follow-up PSMA scans to see how well the cancer is responding.
