I'm curious what doctors and researchers are saying about when to do a PSMA PET scan in response to recurrent measurable PSA after ADT.
I had an RP in 2015. That gave me 8 months of undetectable PSA. A year of Degarelix (Firmagon) + Apalutamide (Erleada) bought me more than 2 years of undetectable PSA. Now the PSA is climbing past 0.5 with a doubling time of about 5.5 months so a GA68 PSMA PET scan is probably the next move.
I wonder how long to wait before getting the scan. I had a PSMA PET scan in 2017 when my PSA was at 0.56 and nothing was found. I don't want to jump too early and find nothing. I don't want to jump too late and find that the lesions are too many to be treated with metastasis-directed radiation therapy.
Is there a sweet spot -- a PSA range where the PSMA PET scan is likely to do the most good?
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Revcat
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When I had Lu 177 PSMA in 2016, the germans told me to do the PSMA PET/CT when the PSA was around 0.5. These tests have a 90% or higher detection rate with a PSA of 2 or higher.
I would do it with a PSA around 1 and if negative wait until PSA is 2 or PSADT starts getting shorter.
There's no evidence that metastasis-directed radiation accomplishes anything (no one knows if it does or it doesn't), but there is evidence that systemic therapy does. There is evidence that docetaxel might keep anti-androgens working longer:
from my understanding of his history, he is not mcRPC and the article reflects on the effectiveness of the drugs in a mcRPC setting. I am just trying to understand so I can relate it to my case as it seems to me I am in a similar situation.
wow, this is new news to me. I thought the only definition of castrate resistance is being castrated ( T is less than 20 or 50), chemically or physically AND the psa is rising. Since he is not on ADT for more than a year and half, so I am assuming he is not castrated. Sorry for the back and forth, just trying to understand.
He wrote:"A year of Degarelix (Firmagon) + Apalutamide (Erleada) bought me more than 2 years of undetectable PSA. Now the PSA is climbing past 0.5 with a doubling time of about 5.5 months "
So I interpreted this to mean that Firmagon+Erleada gave him 2 years of undetectable PSA, but now his PSA is 0.5 with a PSADT of 5.5 months. What makes you think he stopped using Firmagon+Erleada?
He said he was on Firmagon for 1 year. during that year, obviously his psa was undetectable. He never said he was on Firmagon for 2 years where his psa was undetectable. So, I assumed that he stopped Firmagon after 1 year and his psa continues to be undetectable for another year. In that second year, his T has recovered and now his PSA becomes detectable. This is exactly what happens to me and now I am trying to figure out at what level of psa should I get a psma scan and resume ADT. Thanks for the discussion.
Ahk1's reading is the correct one. Apologies for the ambiguity. I had only one year of Degarelix + Apalutamide. In early 2018, after 68 Ga PSMA PET scan revealed no avid metastases, I entered the PRESTO clinical trial. I was randomized to the arm that received one year of Degarelix + Apalutamide. Treatment ended in February 2019. My testosterone rebounded quickly, exceeding 50 one month later. In April 2021, 26 months later, my PSA became detectable again In August 2022, my PSA exceeded 0.2 for the first time. By the definition of time to progression used in PRESTO (from testosterone > 50 to PSA > .2), my time to progression after treatment was, therefore, 41 months. I think this qualifies me as someone of biological interest. LOL. Here's from an exchange between Drs. Charles Ryan and Rahul Aggarwal regarding the PRESTO trial:
Charles J. Ryan: Do you know yet, are there outlier patients who take the therapy for a year and then years are seeming to pass and they're not having PSA recurrence?
Rahul Aggarwal: Yeah, absolutely. These outliers are fascinating. What makes their cancer so hormone sensitive that their testosterone recovers in its years before the PSA starts to come, we did see those patients. Whether there's a big difference between treatment arms there, we need longer follow-up to see, but the biology of those patients, regardless of treatment arm, I think is going to be very important.
Charles J. Ryan: I totally agree, and I think we're going to have to look at, if we can, androgen receptor status, androgen metabolism status, obviously tumor genomics may drive a lot of this as well. A great top-line data. Congratulations, really important study. I think it accrued well, rapidly, and with a very good patient selection criteria. Obviously, a lot more to learn from this trial.
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This colloquy took place after the first interim report on results of the PRESTO trial was presented at ESMO 2022. My 41 months stacks up well against my cohort. With ADT plus apalutamide versus a control group who received AD only, the experimental group experienced a median improvement in time to progression from 24.9 versus 20.3 months, with a hazard ratio of 0.52 and a p-value that met the efficacy boundary.
Bottom line, I responded very well to the initial one-year ADT+ and I've had a four-year vacation from treatment. Not bad.
I did not have an RP but I did have my prostate radiated back in 2014. I’ve been on ADT since day 1 - first Lupron and then added Xtandi and dutasteride in 2015 per Snuffy Myers, been on that regimen ever since. I was undetectable for a little over 6 years. A little over a year ago my PSA became detectable again on the US PSA test I’d been using all along. When it hit 0.17 my PCa specialist MO - Dr. Sartor recommended a PSMA scan even at that level. He said after long term ADT he’s seen cases where it shows nothing, a little or a lot at low levels of PSA. I had the PSMA scan performed last month and it showed a highly suspicious spot on my rib which I had treated with SBRT. We’ll see what happens to PSA and subsequent scans, Sartor told me to be patient, it could take 2-3 months.
Or it often may take even longer, perhaps a year + to reach a final nadir after SBRT. Any downtrend is encouraging. SBRT is usually successful in eliminating the target lesion. But must be vigilant for recurrence at other sites by monitoring with annual scans. See my prior posts on Lu-PSMA-J591 for going after remaining unseen micromets.
With a PSA now above 0.50 and newly CR now is a good time to get a PSMA scan, either Ga68 or Pylarify whichever is most available to you going forward. If you can identify where remaining cancer is located you can plan treatment strategy most appropriately.
In researching my original question further, I came across one proposal that a PSMA scan at PSA 0.3- 0.8 is optimal but can't find it now. I'll post and try to contexualize if I come across it again. One of the problem with taking journal printouts to bed with me is that I can't remember the next day what I highlighted the previous night and what I merely dreamt I highlighted. I think this was real and will reappear.
In March 2019 I had a psma scan done at NIH when psa was between.5 and .6, it didn’t find anything. In 9/2020, the psa was 1.5 and did another psma and it found many LN in pelvis and abdomen. It’s hard decision to make. Now, I find myself almost at the same junction, psa still at .05 after about 16 months off ADT and not sure when to get another psma and resume ADT.
In 2017, I had a PSMA scan done at UCSF when PSA was in about the same range and didn't find anything either. If I get scanned against soon with a PSA <1.0 ng/ml, I wonder whether the result will be the same.
According to Rogowski et al., Radiotherapy of oligometastatic prostate cancer: a systematic review, Radiat Oncol (2021) 16:50, in five relevant studies, detection rates of 15-58%, 25-73%, and 69-100% were reported for PSA ranges of 0.2-0.5 ng/ml, 0.5-1,0 ng/ml, and 1-2 ng/ml, respectively. Based on three relevant studies, the authors of the review wrote: "A PSA threshold of 0.3 to 0.83 ng/ml appears to be an optimal cut-off value for using PSMA PET/CT as staging."
That is the closest thing I've found to a recommendation that speaks to my original question.
As with most things related to PCa, we have to decipher what the odds mean to us. What are we going to do with the results of the scan? What do our doctors say are reasonable treatments? What chances are we willing to take?
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