Question About Scans and Low PSA
My question is are results from the use of C11 Pet scans with low PSA values determined simply by a matter of probability with high GL being the greater probability? I noticed Dr Eugene Kwon reporting C11 Choline Pet scan results on patients having a PSA of 0.
How do you determine when to use these types of scans - particularly after having already gone through treatment (surgery or radiation) and with a low PSA? Is it incorrect to assume that these types of scans should only be used when the PSA rises to predetermined value?
Comments
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Highest probability in detecting the bandit
D
In my opinion, our main purpose in undertaking the C11 PET/CT exam is to locate the cancer. We know that we got it because of an increasing PSA or symptoms, and want to tackle it the best way possible with the intent of “killing” it for good (with surgery or radiation), or, in the impossibility of cure, at least have a better diagnosis of one’s status. If cancer is found in an organ or in a place restrictive to operation then one can avoid those treatments and chose a palliative way that best fits his preferences.
In other words, the exam should be done when the conditions are propitious for a positive result avoiding false negatives to the maximum extent, but not too late that would allow the bandit to spread freely. We should look for the highest probability in detecting the bandit.
Through experiences and trials we know that the traditional CT, MRI and Bone scintigraphy scans are not reliable in small size PCa lesions, however, the combination of PET/CT have shown better results when using particular contrast agents. From trials it was found that some contrasts have better outcomes (positive results) depending on the grade of the cancer (Gleason) the level of the PSA (size) and spread (location). C11 and F18 choline and the novel tracer PSMA seem to be the best choice but the 18F FDG (fluorodeoxyglucose) is practical in symptomatic osseous lesions. The best level in terms of PSA for all the tests is above 2.0 with the new tracer PSMA improving the possibility of detection in levels above 1.2.
Dr. Eugene Kwon may have his own particular threshold table he trusts to be good but such level of PSA=0.0 is not judged as a proper marker in trials worldwide.
I would recommend you to draw conclusions after reading the details in these links;
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3843747/
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3012154/
Best wishes for peace of mind.
VGama
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Pet scan c11Old Salt said:Ask!
Why don't you ask Dr Kwon what the rationale is for doing the scan(s)?
Is it possible you are in a clinincal trial?
Another place for advanced pet ct scan using c11 acetate is in Arizona, Dr. Fabio Almeida runs this one..
https://www.youtube.com/watch?v=WfzVi9mlMtMAlso UCLA does this pet scan as well.
As Vasco mentioned in order to be a candidate, your PSA has to be high enough so that the tests can be effective.
As I understand you have to pay out of pocket
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Has anyone read of work towards a new, better, more thorough PET scan? Badly needed. I had prostrate surgery with the prostrate gland totally removed, so said my urologist. BUT, subsequent blood tests show my PSA count not zero as expected but rising, albeit from a low level. And another PET scan showed nothing. So, PSA particles exist but are undetected in the current PET scan technology. Help. Peter
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Hi Peter,
I notice that this thread is nine years old and that you have replied to it in an attempt to learn more. Nothing wrong with that!
PSMA PET Scans are the go-to nowadays. I'm not sure how they differ from the ones talked about in 2015, but from what I understand, they are more sensitive. I have had three of them, yet my cells remain undetected. I got my first one when I hit the official biochemical recurrence PSA reading of 0.20 in March 2021 which was almost six years after my surgery. The next one was when my PSA reached 0.38 about a year later. My last one was in February last year when my PSA spiked to 0.57.
My PSA is currently 0.74 but I will wait until it reaches 1.0-ish before I get another scan. Clearly, all my previous scans were unnecessarily early.
I cannot find the source now, but this is what I wrote down regarding the success rate of cancerous cell detection from undergoing a PSMA PET Scan vs. PSA from some research I did quite some time ago:
PSA 0.2 to 0.5, detection rate 57.9%
PSA 0.5 to 1.0, detection rate 72.7%
PSA 1.0 to 2.0, detection rate 93.1%
PSA 2.0+, detection rate 96.8%. Unfortunately, I didn't know these stats before my first two scans and in my case, my PSA still wasn't high enough in the third.
How long ago did you have your surgery? What was your Gleason score at surgery? What is your PSA reading now? What is the calculated PSA doubling time? Those last three factors determine how aggressive your remaining cells are, and taken together, will determine your future surveillance and treatment.
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Hi there,
New light on this vexed matter. Thank you. I will ask my urologist about Gleason score and other factors. One explanation I heard today was that removal of the prostrate gland also removes a holding cup or container. And once gone, particles undetectable on a PET scan are freed. Hence the rising PSA count. Need to be a doctor to explain this right. That is roughly it.
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Hi,
What are your latest few PSA readings? Even with your Prostate removed you will have a small PSA reading using the Ultra sensitivity tests, normally around .02-.05 range. Your Cowper's gland produces a small amount of PSA.
Dave 3+4
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Hi, Peter (dogdog)
I believe that your doctor was referring to the "skin" that encloses the prostate gland, the seminal vesicles and the urethra that was cut when dissecting the gland. Typically these cut edges are analyzed by the pathologist (under the microscope) to verify if some prostatic cells have escaped the shell.
The rising PSA may mean that some of these cells have been left behind and now are producing PSA serum.
A constant increase of the PSA may signify recurrence of the disease. Your doctor may be now trying to define your clinical status to recommend further treatment. Salvage radiotherapy (SRT) is typical.
The survivor On-a-journey above explains it well. The PSA produced by those existing cells may not be enough to be detected by the PET scan. All these exams have limits in detection so that one needs to wait for the rise of the PSA if the intent of the scan is to locate the hiding place of the bandit.
You may want to follow the SRT "blindfold" without the exam or have it done with more evident data of the areas to be attacked.
How old are you?
Best wishes and luck in your journey.
VGama
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