Axumin vs PSMA scans

I should have searched the internet first.

Apparently with high PSA (ie above 2.0 in the recurrence setting), the Axumin scan is just as good:

“I think in the recurrent population, as you get to relatively high PSAs of 2 and above, the sensitivity or detection efficiency on all these radiotracers converges and is better than anything we've had a few years ago and definitely better than our conventional imaging has been.

At really low PSA levels—the 0.2 to 0.5 range—particularly with biochemical recurrence, there seems to be a distinct sensitivity advantage for PSMA. And that’s a clinically relevant note for men that are being considered for a lot of salvage treatments or an attempt to cure. So, I do think that PSMA has an advantage over fluciclovine F 18 in that context,” said Rowe.”

https://www.urologytimes.com/view/expert-compares-psma-imaging-agents-discusses-psma-vs-axumin-in-prostate-cancer

It seems logical that the goal should not be binary, that a cancer source has been or not been found per the scan, but that the “full extent” of any spread has been determined for treatment purposes.

The Ga scan showed a hot lymph node but it may not be sensitive enough to find a early stage bone met that a PSMA scan may show due to being a higher sensitivity test, same reason a 3T MRI is preferred over 1.5T scan. The “whack-a-mole” treatment process would seem to work best if the “full extent” of spread was known to the oncologist. There is a point where local treatments don’t make sense unless in the context of a larger plan.

Obviously, the problem is that “full extent” can not be achieved by any scan given the nature of blood borne cell circulation, micromets, and so on. However, the PSMA technology is so promising that I would think that it would provide more more and hopefully better treatment information if once can swing it with insurance, VA, etc.

Having such a large PSA after surgery (3.6) seems like a lot to be blamed on one node unless it is the size of a golf ball. I would be pretty concerned as I have not seen such a large post-op PSA before in my readings but sure it has happened. Hope it is that simple though.

RobLee - I looked up Garyi and it looks like he was at 0.54 at 4 months post-op. I am sure someone has failed miserably but most I recall are between 0.10 - 1.0 at 3 months which is why I was surprised at such a high value and only coming down from 4.1 pre-op.

My PSA was .2 two weeks after RARP so I got put on leuprolide chemotherapy, then the first round of RT. After those treatments had run their course, my PSA went back up to 3.3 Ng/DL. I got the Axumin PET. RO and Uro both said the PSA had to be at least 3 Ng/DL before the PET scan would show the cancer.

Axumin is a non-functional protein analogue. The protocol is no exercise for 48 hours before the test. That keeps your muscles from uptaking much of the Axumin from your bloodstream. Cancer cells are very hungry, so they disproportionately absorb most of the Axumin synthetic protein.

The Axumin is chemically bound to F18. F18 is an isotope of Fluorine. It has a half life of 111 minutes. F18 is made by bombarding a sample of pure water - H2O - with a proton beam until a bunch of the "O" - Oxygen 18 - takes up a proton to become Fluorine 18, That water sample is then combined with the Axumin and injected into the patient.

As the F 18 decays it emits an anti-proton and returns to being Oxygen 18. The anti-proton rapidly encounters a normal proton in a nearby atom. Those 2 particles then mutually self-annihilate resulting in a pair (2) of conic (cone shaped) beams of gamma radiation at 180 degrees from each other, much like the x-ray beams from the poles of a pulsar. Within the PET scan cylinder, those gamma beams encounter the sensor array and create a picture of the area generating the radiation pulse. (as a hard - core Trekkie, I was most entertained personally hosting an antimatter fusion reaction, even on a small scale).

My RO says that the Axumin scan is very close to as detailed and accurate as the Gallium scan. The Axumin PET pictures were very clear to me, there was no ambiguity in the images - 3 fat, glowing pelvic lymph nodes (average diameter ~ 1.5 cm). We proceeded with the ORIOLE - style radiation therapy which ended 1 year ago. Next 3 month blood test is tomorrow, next RO visit next Monday. Side effects from the leuprolide and Xtandi chemo are still very much present, though I have been off them for a while now.

Decaying dead cancer cell proteins in the blood after radiation treatment often encourage a burst of B (invader identify) and T(hunter-killer) immune cells. The hope is that this increased immune system output translates into increased immune system response to any stray metastatic cancer cells that may be scattered around or hiding elsewhere.

Yes, my PSA never was undetectable after surgery, or after SRT for that matter.

Four months after surgery it was up to 0.054. There was a 1" tumor on my cavity wall, near the apex, that Da Vinci and my surgeon, Dr. Mark Gonzalgo, missed, but a PSMA at the NIH found.

Gonzalgo had a very good CV:

Education & Training

Memorial Sloan-Kettering Cancer Center
Fellowship, Urology, 2006

Johns Hopkins Hospital
Residency, Urology, 2004

Johns Hopkins University
Residency, General Surgery, 2001

Johns Hopkins University
Internship, General Surgery, 2000

University of Southern California Keck School of Medicine
Medical School, 1999

Now my PSA is starting to climb again. I had another uPSA blood draw today. And so it goes.

Thanks Melaine.

I was still on a 6 month injection of Eligard (leuprolide chemotherapy or 'ADT') + Xtandi (androgen agonist chemo) when I got the 3 hot lymph nodes treated with 56 Gy of external beam radiation and the whole set of interior pelvic lymph nodes treated with 50 Gy of external beam radiation. I had previously received 72 Gy of external beam radiation to the prostate bed and immediate surround in 2013.The ORIOLE study was/is about hitting the mets with a narrow beam of external beam (stereotactic) radiation, my RO chose to add the pelvic field treatment as an additional treatment to (hopefully) prevent the other pelvic lymph nodes from becoming met sites. "Oligometastatic" means 3 - 5 mets, usually near each other. If they are soft tissue mets like those hot lymph nodes they are especially sensitive to this treatment.

I quit Xtandi last may 29 when it took away my ability to walk (side effect, I am still recovering from that), I did not get the next scheduled dose/injection of Eligard this past Dec 5 so as to judge the efficacy of that external beam radiation in stopping the cancer. If my PSA stays down for many years the treatment worked as designed, if not...I plan to 'lather, rinse, repeat'. If the PSA goes up, I will get another Axumin scan and hit the new met/mets as possible. If they cannot be radiated I will be back on the chems.

Yes, my RO said that - at these PSA levels (above 3 ng/dL) - the Axumin PET does a very good job of showing up the mets. The scan printouts were very clear and detailed. The mets shone like bright stars in the night sky.

Now, I am off to the hospital for that blood test before I walk my Lovely Lady Labrador out in the winter wonderland. I will try and clean up my sig later when I have some time, sorry for the confusion.

Down or steady = good, Gary!

...and - after yesterdays test - I remain at < 0.1.

Garyi, that’s good news about your most recent PSA! It is pretty shocking that a doctor with such outstanding credentials could have missed that tumor. I’m sorry that happened to you. You made the best decision based on the info you had at the time. That’s all any of us can do.

Trailguy, thanks for explaining about your hormone therapy. Great news about your PSA, too!

Post Edited (Melaine) : 3/31/2022 2:03:56 AM (GMT-6)