Advanced Prostate Cancer

Axumin Pet Scan vs Ga68 PSMA Pet Scan

Does anyone have any information or opinion about the respective strengths and weaknesses of Axumin Pet Scan vs Ga68 PSMA Pet Scans for Metastatic Prostate Cancer?

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Hi:

Iti is a complex subject. In a nutshell the Ga 68 PSMA is the most sensitive, detecting metastasis with PSA =/> 0.2.

The problems of GA 68 are: - Cancer may be PSMA negative (very lo % of cancers), they do not have PSMA so GA 68 will give a false negative. Gallium 68 is eliminated by the kidneys and the accumulation of the radio tracer during the study in the bladder may obscure some metastasis.

11 C acetate may follow Ga 68 PSMA in sensitivity and then 11 C choline.

Here they explain:

sciencedirect.com/science/a...

"Review of the current literature generally favors PSMA-based imaging in the setting of biochemical recurrence; nevertheless, more comparative studies are needed to further clarify which pcPET radiotracer is most appropriate in each of a variety of clinical presentations. "

if you are getting an Aximun with a low PSA it may give you false negatives, so a 11 C acetate or Ga 68 PSMA may be indicated.

Anything, please let me know.

Raul

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Thanks Raul

Here are some more questions

1. What is the relative radiation load for PET vs PET & CT vs PET & MRI vs Axumin

2. Are PET vs PET & CT vs PET & MRI even options?

3. Might it be generally best to just wait until you hit 3.0 PSA for any of these tests? If you have a high doubling rate, that is not a lot of time and trade-off may be a much more accurate test.

4. Axumin vs Galium 68

What is the relative difference of load on my kidneys?

false positives vs false negatives (advantages and disadvantages of either)

side effects

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Very good questions. I am not a nuclear medicine person, so I give you my understanding for what I have read in the past and what I talked with some experts.

A MRI has not radiation. A PET/MRI has a better definition of the anatomy and less radiation than a PET/CT. I think the limitation is the availability and cost of the equipment for PET/MRI. They could be an option if the institution have both types of machines. When I went to Germany for Lu 177 treatment they offered me one or the other. I went with the PET/CT because I do not like confined spaces.

The amount of radiation with these tracers is very low since the dose is small and they have a short half life. I think the Gallium has the longest half life around 2-4 hours meanwhile the others I believe have a smaller half life.

In general I was told no to worry at all for the radiation of the tracer they use. I think one should be worry of receiving frequent Ct scans even when they try to use techniques to decrease the amount of radiation. The CT in PET/CT is not exactly the same (less radiation) than a regular CT with contrast.

They recommend to do the Ga 68 PSMA when the PSA is over 0.2-0.4. The higher the PSA the higher the sensitivity. For the Gallium 68 PSMA this is true up to a PSA of 2, then it does not make too much of a difference. This may not be true of the other tracers which are less sensitive than Ga 68 PSMA.

I believe there are not false positives with Ga 68 PSMA and I believe there are few false negatives with PSA between 1 and 2. The Germans do not do GA 68 PSMA if the PSA is less than 0.4 because of false negatives. I do not have info for for the other techniques.

If I were to have a PET/CT I will select the Ga 68 PSMA. In my case I am waiting to have a PSA around 0.5-0.6 to get the study done (actual PSA 0.09). If with the higher PSA the study is + for metastasis I will go to Germany for other Lu 177 treatment.

As far as I know there are not side effects with these tests, except for the IV and the liquid one has to drink with the Ga 68 PSMA.

I'll look for more info and I;ll let you know. Very good questions and they should be researched.

Best wishes

Raul

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1. Wow, what an answer!

2. May I ask where in Germany you went. I am going to be doing an Axumin or a Gallium 68 but I have already had far too much radiation. I want to do the PET with MRI, but I think that is going to be hard to get in the US.

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I went to Technical University of Munich. Do not worry to much about the radioactivity of the tracer. UCSF (Ubiversity California San Diego) I believe has a PET/MRI machine. You coul call nuclear medicine at UCLA, UCSF, Stanford, Mayo Clinic etc and find out.

If the PSA is low I will have a Ga 69 PSMA study. The other advantage of this study is that you will know that the PC is PSMA positive, so you will be a candidate for Lu 177 is ever needed. There are a % of cancers which are PSMA negative.

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"Do not worry to much about the radioactivity of the tracer."

I am not. I am more concerned about the CT part of the PET/CT.

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I agree. In 2016 I had one CT with contrast and 3 PET/CT with Ga 60 PSMA and during 2017 I needed because of other medical problems 2 CTs with contrast and a bone survey.

I believe you could get a PET/MRI. I think Phoenix Molecular Imaging has a PET/MRI and they do 11 C acetate which is a good test.

phxmi.com/

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This is an article with more information about the different tracers or compounds they use for PET studies of PC. It confirms that the Ga 68 PSMA is more sensitive than others and has a very good specificity (very few false negatives).

Kind of dense, but it is the only article I found so far where all techniques are mentioned.

ncbi.nlm.nih.gov/pmc/articl...

Anything, please let me know

Best wishes

Raul

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Raul,

I called Pheonix, they don't do the PET/MRI. They say it is not so common in the US. Do you have some contact information for the German place that you used?

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This is the international office of the TUM Klinikum

mri.tum.de/office-foreign-p...

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Thanks

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Comment from Joel Nowak:

"Nobody can really evaluate one against the other since there has not been a head to head study.

I believe that PSMA maybe more sensitive, however about 15% to 20% of prostate cancers do not emit PSMA so for those people the scan will not be of any value."

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Could you be please put the whole reference of how to find the article you are quoting?. My understanding is that except for NEPC all the other PC express PSMA and NEPC is rare.

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I got this from a private message. It is just Joel's personal opinion.

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"My understanding is that except for NEPC all the other PC express PSMA and NEPC is rare." Raul80

I don't understand. What is "NEPC" and "PC express PSMA "

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nepc=neuroendocrine prostate cancer,

pc=prostate cancer

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LOL still don't understand what you said

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who is joel?

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He is a prostate cancer support leader. He does a call in support on the 2nd and 4th Thursday of each month. See Schedule:

cancerabcs.org/calendar/

He used to be the COO of Malecare. Now you can find him here:

healthunlocked.com/cancer-t...

healthunlocked.com/cancer-t...

healthunlocked.com/user/joelt

And this is his new organization:

cancerabcs.org

CancerABCs@gmail.com

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Thanks!!

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Joel's quote I think it comes from this article:

ncbi.nlm.nih.gov/pmc/articl...

where the authors said that between 5 to 10% of patients with PC, the PC does not express PSMA. However in this article no reference to any study is made. In my opinion this type of statements is worthless. I'll keep looking.....

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From the literature below seems that GA-68 is head and shoulders above comparables in sensitivity and the opportunity for your oncology professional to identify the most appropriate response strategy.

pctrf.org/pca-commentary-11...

sciencedaily.com/releases/2...

I had PSMA PET-CTscans done at Charite in Berlin, very helpful people who all all spoke good english (thankfully) and had a good hour same day with Director of Oncology to review the scans in detail.

Unfortunately when I brought the scans back to Canada they had never had such early and detailed information on pelvic tumor progression and fumbled on how to respond in terms of therapy response. What I got was the 'standard' radiation treatment which I am hopeful will be successful.

Peter

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I have had 2 Axumin PET scan (July ‘17 and February ‘18) and one high contrast MRI (August) but all had been negative despite rising PSA from 09 to 4.2 during that period. So I’d say that Axumin dit not helped me in isolating the met (wherever that is).

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Was the Axumin pet scan done in conjunction with a CT or an MRI scan, or done stand-alone without either?

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To: Raul80

Sir, Again I take my hat off to you!

Good Luck and Good Health.

j-o-h-n Sunday 02/18/2018 3:46 PM EST

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