Accuracy of PSMA PET scan?

[Adendino]

What would you venture to guess is the accuracy of the PSMA PET scan? How many of you showed "no spread" with your PSMA scan, but then learned via surgery or otherwise that there WAS spread which wasn't detected with the PSMA scan? And, how much better is the new Posluma scan vs Pylarify?

My husband is Gleason 9 (4+5) in all cores with SVI and ECE, but PSMA scan showed no spread. His PSA at dx was 13. In the "wives" group I'm a part of, I keep hearing about men who showed no spread on PSMA scan, but went for surgery and had positive lymph nodes, bladder neck invasion, perineum etc. Is this descrepancy a matter of pilot error by the nuclear medicine tech, cancer which doesn't emit much PSMA, or just the nature of the test?

Thanks and wishing all of you a mindful journey which helps you cope with the ups/downs of this disease.

[GP24]

A PSMA scan will detect mets down to about 3 mm in size. If they are smaller the pathologist may detect cancer after the lymph nodes have been removed by surgery. Bladder neck invasion may be difficult to detect because the bladder "shines bright" from the radioactive tracer drug (68Ga-PSMA-11) which is about to be excreted.

[NanoMRI]

I have had three PSMAs, two Ga68 and a Pylarify. All 'clear'. How good were the docs reviewing the imaging? What about second and third opinions? How 'avid' is the patient to various contrast agents? PSMA imaging is relatively new in US, with limited wide spread clinical experience. My first Ga68 was in January 2018; I traveled to Europe for it and also had the 'even better' Ferrotran nanoparticle MRI.

[Cyclingrealtor in reply to NanoMRI]

This?

ferrotran.com/publications-...

[NanoMRI in reply to Cyclingrealtor]

yes this is the agency handling it now, building case to bring it to market. The trial cited is not the only avenue of availability. Interesting side story - this originated in US in 1990s as Combidex - narrated history is dubious. An ongoing research project of mine for possible book.

[Tall_Allen]

PET scans only show metastases of 5 mm or bigger. Many lymph node metastases are smaller than that. You have to treat what you can't see based on statistics of men in that situation. The POP-RT protocol had great results:

prostatecancer.news/2021/08...

[Justfor_]

PET, stands for Positron Emission Tomography. As the name implies, it detects Emissions. It doesn't measure sizes of any sort. This silliness of relating the detection capability with the "size" of tumours is for people that are divorced with physics. It is nothing more than false. If there is enough of the emitting isotope condensed into a sphere of 1 mm, it will show up on the imaging. Equally, if there isn't enough of the isotope loosely distributed within a 10 mm sphere, it will pass unnoticed buried in the background. The mm spec pertains to the imaging resolution, NOT the detection capability. For a layman's parallel take the photo of a clear daylight sky. The sun will show up regardless of whether the picture is shot with an ageing camera of 480x256 pixels of resolution or the latest 64 Megapixel offering. On the other hand, on a cloudy heavy cast day, the sun will be missing from the picture regardless of camera employed. The sun's emissions will be diffused and attenuated by the clouds.

[NanoMRI in reply to Justfor_]

At usPSA 0.13 the Ferrotran nano-particle MRI I share about identified five potential positive pelvic nodes, three suspicious; the Ga68 PSMA PET done the prior day showed no potentials. The shortest diameters in mm, were 6,4,4,3,3. The subsequent ePLND I chose to have instead of ADT/chemo confirmed six metastatic nodes.

[tayninhtom in reply to Justfor_]

Thanks, good to have a scientist among us.

[j-o-h-n in reply to Justfor_]

Me <----- Divorced from first wife and Divorced with physics....

Good Luck, Good Health and Good Humor.

j-o-h-n

[MarkS]

I too had Gleason 9 (4+5) with a PSA of 12.7. Nothing showed on a PSMA PET scan or a separate bone scan. I opted for RT as techniques have advanced a lot more than surgery. My oncologist calculated that the probability of lymph node involvement was 68%. As a result I am half way through 37 sessions of RT where they are irradiating not only the prostate but various lymph nodes and the prostate bed as well.

[Cateydid]

……”wishing all of you a mindful journey which helps you cope with the ups/downs of this disease.”

What a wonderful sentiment!!! Thank you.

My Joe had a PSMA PET scan following 6 doses of Pluvicto. It showed reduction in previous tumors and an uptake in the liver and spleen.

Saw the onc yesterday who is thrilled with the tumor size reduction, never mentioned the new liver/spleen involvement….happy with overall progress (as are we !) PSA dropped again by more than half in the last month: at .21 !

Amazing!!

We have no idea what to expect, so we’ll watch and wait again, enjoying each blessed day.

Joe said he thinks he’s got three months left…..and has no idea where that number is coming from.

Keep on keepin’ on!!!

[j-o-h-n in reply to Cateydid]

Three months left?........................ Which three months and in what years? 1. January? 2. July? 3. November?

Good Luck, Good Health and Good Humor.

j-o-h-n

[FaithOverFear104]

My husband has had rising PSA which began after eight months of an ADT holiday after successful treatment of metastatic disease with Triplet Therapy. His PSA started going up in August and it is now 12.42. He still has his prostate. He had two PSMA PETs both showing no mets and minimal/diminished activity in the prostate. His MO has only said there must be micrometastases somewhere that the PSMA PET isn't picking up. She does not seem interested in offering any other type of scan or testing to find out what's really going on, nor does she seem too concerned about the PSA rise. Only offered him a choice between Orgovyx or Xtandi monotherapy. He just started Xtandi yesterday. Praying it is enough to take care of whatever is going on. I, too, am in the wives group. I hope you find some answers and hope your husband is doing okay.

[j-o-h-n in reply to FaithOverFear104]

When next you see his Doc turn up her hearing aid........(smug slug bug) arrogance arrogance and arrogance........(check out other docs)....

Good Luck, Good Health and Good Humor.

j-o-h-n

[FaithOverFear104 in reply to j-o-h-n]

haha! I hear ya!! Thank you!

[Xavier10]

there is concern that reliance on PSMA is overstated, and that traditional imaging should be used as well.

dailynews.ascopubs.org/do/d...

[NanoMRI in reply to Xavier10]

2nd opinions have been a key part if all my imaging over past nine years - two mpMRI, three PSMAs and Ferrotran nanoparticle MRI.