PSMA PET Scan

PSMA PET scans are specific to PSMA. A PSMA PET scan will identify any organ, tissue, or fluid expressing PSMA.

As it turns out, PSMA (prostate specific membrane antigen) is not really “prostate specific.” There are other organs, tissues, and fluids that naturally express PSMA (without being cancerous) and will show as physiologic tracer uptake on a PSMA PET scan - particularly in the lacrimal (tear) and parotid (salivary) glands, blood, liver, spleen, pancreas, ganglia, and more, as well as the kidneys, ureters and the bladder (as the body tries to quickly excrete the radioligand that was injected).

As always, discuss all this with your doctor when you get your SUVmax scores from your PSMA PET scan report.

Dr. Johnson (of Mayo Clinic) talks about all this in his presentation, starting with the scans we’ve all heard about (MRI, bone, & CT scans), and then going into detail about PSMA PET scans: https://youtu.be/JoJomACA5UM

For what it's worth, I'm 54 and was recommended surgery, without a single one of my nine doctors recommending radiation (3 x urologist, 3 x radiation oncologist, 3 x medical oncologist). I was 3 + 4, but I was told to avoid radiation since I was likely to live long enough to see the side effects of it and was healthy enough to overcome the surgery and any side effects. There is also a chance of irradiating your bowels, meaning your incontinence issues could be much, much, worse. That chance might be pretty small, but it was clear: radiation as a back up method if RARP doesn't work.

Thank you for the info. My PSMA PET Scan SUVmax is 7.1 and described as Moderately Intense.

While normal radiation, can cause problems after many years proton radiation has been used in children and younger people because it has a very low incidence of side effects.

If you watch the 2023 PCRI Video and see Dr. Carl Rossi talking about radiation you find some interesting things. For one he’s been doing Proton radiation treatments since 1994 when they built a building for the machine in San Diego. The first patient was the person that invented it, He lived to over 100. He has done Proton radiation on over 13,000 prostate cancer patients.
That video link is

Stanford Edu

In a study of about 145,000 men with prostate cancer, the team found that the rate of developing a later cancer is 0.5% higher for those who received radiation treatment than for those who did not. Among men who received radiation, 3% developed another cancer, while among those who were treated without radiation, 2.5% developed another cancer.
Here is a link to the full study from Stanford
Prostate radiation only slightly increases the risk of developing another cancer, Stanford researchers find
https://med.stanford.edu/news/all-news/2022/070/prostate-radiation-slightly-increases-the-risk-of-developing-ano.html

Here’s how they grade them —>

“SUV” stands for “standard uptake value” and is a measure of radiotracer uptake that indicates how high grade the cancer is. The higher the SUVmax, the more advanced the cancer.

So, they use the PSMA SUVmax values of your blood (as the lowest level), liver (as the medium level), and parotid (or lacrimal) glands (as the highest level) of SUVmax expression for comparison.

If a suspicious area (lesion) is expressing PSMA, and it has:
> a PSMA SUV score less than blood, then it’s not likely cancer, but instead just normal, background PSMA cellular expression;

> a PSMA SUV score greater than blood, but lower than liver, then it’s likely low-grade prostate cancer;

> a PSMA SUV score greater than liver, but lower than lacrimal/parotid glands, then it’s likely moderate-grade prostate cancer;

> a PSMA SUV score greater than parotid glands, then it’s likely high-grade prostate cancer.

Interesting. So how do I determine if my 7.1 is low, medium or high??

It might be worth noting that other tissues light up on PSMA PET/CT. The salivary glands, bladder, etc. But the radiologists know that and take the appearance elsewhere into account.

Thanks North, you’ve always been very helpful!

Discuss your case with ChatGPT and you will get a correct answer to your question. It's shocking how accurate it is compared to what 2 urologists, 1 oncologist and the Mayo clinic urologist told me. The more details you tell it the better the resonse.