Cyberknife

After RRP in 2011 and SRT in 2012 both failed, followed by 2 cycles of IADT, i decided to do 68Ra PSMA PETCT.
At a PSA of 0.27 and T=455 the result was annoying.
Conclusion:
-when considered in context of increasing PSA value the moderate PSMA uptake in the fossa of left seminal vesicles has to be assessed as a local recurrence of the prostate cancer.
- The New sclerotic lesion with moderate PSMA uptake in L3 is highly suspicious for bone metastasis.
-The very moderate PSMA (left skapula) without correlative in the CT is not typical for bone metastasis( probably due to injury)
and should be reevaluated.
I contacted a cybernife clinic in Germany and they accepted to do the radiation. I don't know how effective it will be(reluctant).
What other options I have?
Thanks to all of you.
Maybe Tall Allen will chime in .thanks TA.
Ali

Darie-

I'm surprised that the PSMA PET showed anything when your PSA is that low. I share your concerns that any more spot radiation may be pointless. The trials so far where they go after one met after another (whack-a-mole) have had disappointing results - after 5 years, all but 15% had more distant metastases. If it is safe to zap the L3 lesion, that may save you problems there further down the line. You already had radiation to the seminal vesicle fossa when you had SRT, so I would be concerned about radiation damage from putting more radiation there - but that is something your RO can better address. I think it is better to use systemic therapy than local therapy, and your iADT seems to be working well. Early Chemo may be useful too if your metastatic burden increases.

Darie,

maybe they do it since it is a salvage radiation. Usually they reject making a primary treatment if there is extracapsular extension. (Ask them to treat your bone metastases too)

If you are doing hormone therapy the PSMA PET/CT will display well at low PSA values. I did one at 0.09 ng/ml (while having ADT) and it showed the same result as the one done at PSA 19.9 ng/ml without ADT.

As I wrote in a different thread:

Ali Afshar-Oromieh (Heidelberg group) writes: "Patients with an ADT at the time of 68Ga-PSMA-ligand PET/CT more frequently showed a positive PET scan compared to patients without such treatment" www.ncbi.nlm.nih.gov/pmc/articles/PMC4315487/ There is no explanation for this observation though.

George

Post Edited (George_) : 9/22/2016 2:07:54 PM (GMT-6)

Darie-

While PSMA PETs are good, they are not able to find small mets when PSA is low, unless the PSA is rapidly rising (which indicates high metastatic activity). In men with PSA 0.2-0.5 detection rate was only 58%. Yours was at the bottom of that range. Your PSA velocity of 1 ng/ml/yr is also not very fast, but adds perhaps to the sensitivity (82% for PSA velocity in that range). I don't know what the sensitivity is for the combination of low PSA and low velocity, but it's probably not very high.

jnm.snmjournals.org/content/56/5/668

But that is just the sensitivity. You have to know its specificity as well. That means, what % of the lesions that are actually negative will seem to be positive (false positives). Researchers in Germany have observed that in areas of faint uptake, "Caution has to be taken in these cases it remains unclear whether this uptake is really related to bone metastasis or might also constitute false positive findings." And some have found cases where an old bone fracture looked like a bone met on a Ga-PSMA PET. There are false positives, certainly at this low a PSA/velocity, so it makes sense to do further investigation.

journals.lww.com/nuclearmed/Abstract/2016/07000/Healing_Sacral_Fracture_Masquerading_as_Metastatic.29.aspx

Another patient on HW (traveller?)recently moved to Casodex monotherapy with good results. I think it is very individual and hard to make generalizations.

George-

That's even worse than the 58% detection rate the other group quoted. You reaffirmed what I said -- The detection rate is not very good below 2 ng/ml. And it's very bad below 0.5.

Who are the "some doctors" who do not think there are false positives? Do you have a reference?

- Allen

George_ said...
The percentage of false-positives and false-negatives is controversial. You could only determine that percentage if you had a better diagnostic tool to compare the findings.

I don't think it is controversial. Is that just your personal opinion, or have you seen evidence?
There are certainly tools for determining whether a positive is a false positive - biopsy, growth, shrinkage with ADT or chemo, and nothing on repeat scans.