PSMA PET Scans...some interesting info

What's interesting to me is that my treatment plan was written the week following my biopsy results of May 13th. My PSMA PET results were not available until June 8th. The treatment plan did not change one bit, nor should it have.

@heavyphil 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 avid 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).

So, I wouldn’t consider it “subjective”, but as taking a very well-trained eye, as well as using results from other diagnostics in order to make a determination.

As for whether a PSMA PET scan would show a discernible SUV increase in a lymph gland at a 3 month interval would depend on the aggressiveness of the cancer. If the PSA was low, perhaps not; if the SUVmax was less than the SUVmax of blood, also perhaps not.

A high PSA Velocity could be from a lesion anywhere in the body, thus the PSMA PET scan to try to find where.

As for necessary treatment, that’s where Dr. Kwon’s statement comes into the picture again —> “…. only 1/3 of men who have recurrence following prostatectomy have recurrence only in the prostate bed; they should not get salvage radiation there unless they’re absolutely certain of the location of recurrence; first confirm where the recurrence is.”

@brianjarvis Just so. We discovered my prostate cancer via the lesion on my spine. There was no evidence of local spread in imaging (MRI, CT contrast, bone scan) and not even anything visible in the prostate itself. The cancer seems just to have taken off out of the nest (prostate) almost as soon as it was hatched and settled in my middle spine.

@heavyphil

Exactly. There are tissues that regularly "glow" and they are "dismissed" when reading PSMA and also some scar tissues that are inflamed and can have pretty decent SUV. Yes- that is why PSA is important factor but what if PSA is rising and scar tissue is glowing on a long ago broken rib, let's say ? It is a good chance it might be designated as bone met. The same goes for nodes - they might be inflamed due to viral infection at that particular moment and have very decent glow and be designated as cancerous ? Even vaccination can cause false results
https://pmc.ncbi.nlm.nih.gov/articles/PMC9169609/
I know Phil - I should stop reading 😆, or perhaps I should stop posting such scary facts 😬...

@northoftheborder

Yes - I think that the only way one can say with GREAT certainty if spot is PC or just something else is by using MRI and CT in conjunction with PSMA. It would be even better if all of those were done once before and can be compared over time.

As my doctor friend told me once - "it is all just like reading "shadows"- it can be this or that ", and for the real conclusion one needs to use multiple and different parameters and different modes of testing.

Thanks for sharing this article - I am inclined to dig into the this further and follow these quoted clinicians. We were diagnosed with lung only PCa mets, and agressively treated, based on PSMA Pet alone, and with SUV max ‘faint’ < 2. We got a new Oncologist mid treatment who commented ‘indolent’ and ordered conventional CT and Bone scan for next follow up in 6 wks. We heard , “agressive, sneaky cancer” from one and “indolent” from another and I have had a hard time incorporating those divergencies The 2nd GU Onc falls in line with this article when they said to us, “we are still learning about the shiny new thing” when they ordered the conventional scans at the last visit. This all really fits - irs like my hub’s RARP in 2008, which was “the shiny new treatment” back then - seems he may have fallen on that sword twice now - quite the conundrum.

It must be a real dilemma for doctors when a new technology like PSMA-PET emerges.

On the one hand, they don't want to miss a chance to help their patients in a way they couldn't before. On the other hand, they don't really fully understand the new technology yet, and especially not its long-term impacts.

Oncologists are humans like everyone else, and in the end, they're going to make intuitive decisions until there's a big enough body of research to let them make purely evidence-based ones.

👆🏼Thus exactly. There is such a tendency for knee-jerk reactions when you hear, ‘cancer’, ‘metastic’, ‘ it’s back’, etc, that you think you want to go for ‘ the best’ new tools and treatments. It is a dilemma. We watched PSA after RARP for 17 yrsbefore a PSMA Pet - seems we were ‘conservative’ after wondering if the side effects from surgery were worth it; but RARP was happening ‘back then’ and ‘PSMA Pet’ is happening now. It will be interesting to see how the tech is incorporated in 5-10 years… Don’t look back.

True story. My diagnosis was 4.10 years ago, stage 4 aggressive. Shocker. One month in on radiation treatments. Family friends who owns a private-medical-destination business informed us of this new treatment in Germany, costs a lot, but it's great. It turned out to be a PSMA Pet Scan. We didn't do it. Stayed local, completed triplet therapy in six months and have been living a normal up-and-down stage 4 life. Had my first PSMA-Pet six months ago, it was helpful, radiated a few new spots, but overall it aligns well with my theory. here's my theory, "There is no magic cure, there are good treatments, find a two oncologist you like, one local, one at a NCI Research teaching hospital, mindful moderate exercise 60-90 minutes per day, think nutrition not diet, live well, love much and challenges your mind with great books and meaningful conversations with friends while striving to live your best version. "

@brianjarvis Thank you, Brian, for the link to Dr Kwon’s presentation. I like his speaking style so much more than many of the other experts.
But here’s the one thing I don’t get - and probably it’s MY fault for not getting it - but he says we always want to treat earlier rather than later; great, I agree…
…but then he makes that statement about NOT treating anything until you can see it, since only about 30% of men have recurrence in the prostate bed…Huh?? He just said to treat it early, ideally < 0.2…
I went back and reviewed my own PSMA: clear with no sign of activity ANYWHERE - not even in the ‘focal bed’, yet my PSA of O.18 prompted treatment.
Don’t get me wrong, my PSA was rising - but slowly and inconsistently over a period of about 18 months; NOT on a pace where PSA velocity was even an issue. It was more like: only PCa would cause a consistent rise in PSA over time, not ‘normal’ tissue left behind from surgery…who really knows, right?
Anyway, I had 25 radiation treatments to the bed+ pelvic nodes and 6 months ADT and am now undetectable.
But isn’t Dr Kwon saying that I should not have done anything? I should have waited for bright lights on my PET since nothing was visible? Wouldn’t that be too late rather than too early IF I was one of those men in the 30% whose recurrence was still confined to the prostate bed?
@jeffmarc has mentioned Dr Kwon’s preference for SBRT on visible lesions (over SRT on invisible ones) many times - and Dr Kwon illustrates this treatment with a few actual cases he’s successfully treated using this approach.
But what I think would be more telling, is how many cases slipped thru the cracks and became widely metastatic during the interval where lesions were invisible and then when they lit up like a Christmas Tree…? Nobody bats 1,000 pct- not even Dr Kwon and unless I am interpreting what he is saying incorrectly, his approach sounds like a bit of Russian roulette to me…
I have no regrets whatsoever that I opted for SRT - even in light of a negative PSMA. My PSA could still be rising to levels portending an unfavorable outcome (>0.7) and my PSMA could STILL be negative…How can you wait?? Best,
Phil