Was very interested to read (on this site) recently about the lecture given by Dr Eugene Kwon of the Mayo Clinic regarding the treatment of Oligo Metastic Prostate Cancer. Some background information for you. DX 2011 Gleason 7 and as part of the DX was discovered to have 1 met to part of one of my ribs - which was subsequently removed. Straight on to Zoladex every 3 months. 6 months later, upon my requests, underwent radiation treatment to debulk the cancer in the prostate. PSA then declined to <0.01 and remained there for over 18 months. I stopped zoladex almost 18 months ago now. Been a slight increase over the last 6 months. First to 0.01, then 0.02 and last test this week came in at 0.04. Not so happy about the increasing number but my T is back to normal and the PSA is still very low.
My Med Onc has said that once the PSA gets to about 0.5, I will have a PSMA Pet scan (new to Australia) and if they detect just a few mets - then they will use radiation to zap them with the hope of maintaining my health without the need of going back on zoladex.
My question concerns part of Dr Kwon's lecture. He mentioned some patients that had a Choline C 11 Pet scan even when their number was <0.01. I am not sure about the sensitivity of this type of scanning but I believed that you had to wait till the PSA had risen to a higher level before scans could be accurately undertaken.
Unfortunately, the Choline C 11 Pet scans are not available in Austrlia but should I be requesting the PSMA scan much sooner?
Thanks guys
Written by
PhilipMac
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PhilMac, you've got very low insignificant PSA levels that many of us, including me, envy.
I'm not a doctor but the course proposed by your med onc seems to be a good one, having regard to the scientific literature. I had my first PSMA PET when my PSA was 0.7.
Lower than 0.5, I doubt whether you'll get the sensitivity on either PSMA or Choline C 11
PSMA PETs are not new in Australia and have been around for several years. Choline C 11 PET scans are available in Australia through clinical trials.
It would be helpful to know more about where some of the other big cancer clinics stand on PSMA -- e.g. Mayo, Sloan Kettering, MD Anderson, Dana-Farber. Obviously they must know about it, but what use, if any, are they currently making of it?
I don't believe that PSMA scans are yet approved in the US, despite their very common use in other countries like Australia. In many ways, especially in the scanning technology areas the uS is way behind the rest of the world.
My memory is that the Kwon scan is not nearly as sensitive as you indicated. The FDA prescribing information indicates that it is not sensitive below a PSA level of 2 ng/mg
The PSMA scan is more sensitive and if it is available to you it is the best way to go at this moment.
Here is an August paper where PSMA & Choline PET scans were compared.
"PET using 68Ga-PSMA-11 showed a higher detection rate than 11C-choline PET for lymph nodes as well as bone lesions. However, we found lymph nodes and bone lesions which were not concordant applying both tracers."
Prostate-specific membrane antigen (PSMA) is expressed ubiquitously on the membrane of most prostate tumors and its metastasis. While PET/CT using 11C-choline was considered as the gold standard in the staging of prostate cancer, PET with radiolabelled PSMA ligands was introduced into the clinic in recent years. Our aim was to compare the PSMA ligand 68Ga-PSMA-11 with 11C-choline in patients with primary and recurrent prostate cancer.
METHODS:
123 patients underwent a whole-body PET/CT examination using 68Ga-PSMA-11 and 11C-choline. Suspicious lesions were evaluated visually and semiquantitatively (SUVavg). Out of these, 103 suffered from a confirmed biochemical relapse after prostatectomy and/or radiotherapy (mean PSA level of 4.5 ng/ml), while 20 patients underwent primary staging.
RESULTS:
In 67 patients with biochemical relapse, we detected 458 lymph nodes suspicious for metastasis. PET using 68Ga-PSMA-11 showed a significantly higher uptake and detection rate than 11C-choline PET. Also 68Ga-PSMA-11 PET identified significantly more patients with suspicious lymph nodes as well as affected lymph nodes regions especially at low PSA levels. Bone lesions suspicious for prostate cancer metastasis were revealed in 36 patients' biochemical relapse. Significantly more bone lesions were detected by 68Ga-PSMA-11, but only 3 patients had only PSMA-positive bone lesions. Nevertheless, we detected also 29 suspicious lymph nodes and 8 bone lesions, which were only positive as per 11C-choline PET. These findings led to crucial differences in the TNM classification and the identification of oligometastatic patients. In the patients who underwent initial staging, all primary tumors showed uptake of both tracers. Although significantly more suspicious lymph nodes and bone lesions were identified, only 2 patients presented with bone lesions only detected by 68Ga-PSMA-11 PET.
CONCLUSION:
Thus, PET using 68Ga-PSMA-11 showed a higher detection rate than 11C-choline PET for lymph nodes as well as bone lesions. However, we found lymph nodes and bone lesions which were not concordant applying both tracers.
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