When to start salvage radiation therapy

[Johnko]

When to start salvage radiation therapy

Just a quick question.

I have found different psa values recommended to start salvage radiation therapy.Apparently to my understanding the earlier the better.

I found different numbers ranging from 0,03 to 0.2 with a huge difference in relapse free survival

[Tall_Allen]

You can discard old observational studies like the ones that are creating your confusion. We now have the results of a major randomized clinical trial (RADICALS-RT) that proved that waiting for 3 consecutive uPSA rises or PSA to reach 0.1 ng/ml gives equivalent results to immediate salvage radiation. That is true for patients in spite of the fact that they had adverse pathology. 64% of patients with adverse pathology never reached that definition of PSA progression. You can read about it here:

prostatecancer.news/2019/09...

[Johnko in reply to Tall_Allen]

Ok thanks for the info

[Justfor_]

Wrong query, only suited to blind sRT. Read this 2020 Australian-Dutch paper and you will easily understand why a PSMA PET CT (before sRT start) can be more valuable than the earliest of sRT.

"3-Year Freedom from Progression After 68Ga-PSMA PET/CT–Triaged Management in Men with Biochemical Recurrence After Radical Prostatectomy: Results ofa Prospective Multicenter Trial".

jnm.snmjournals.org/content...

[Hailwood in reply to Justfor_]

I think this is the direction that my RO is doing. PSMA PET/CT done last week, results this week, then radiation based on results of the scan starting in a week or so. PSA still at 3.9 despite RP though.

[Justfor_ in reply to Hailwood]

At PSA of 3.9 the PSMA PET/CT has a detection rate in the mid 90%. The remainder to 100% is more due to tumours' lacking PSMA avidity than actual size, hence, bellow detection range. If distant metastases are thus revealed, then we are not talking of an ordinary sRT to the prostate bed +/- pelvic nodes.

The issue of irradiating distant metastases' usefulness is still very controversial, that is why I urge you to thing about it twice. You may get the late toxicities due to the irradiation, albeit the very slim success probabilities (18-40% according to the graph of Figure 2A of the paper already shared). It goes without saying that a RO with suitable past record should be brought in.

My best wish is that tumours confined in the pelvis will show up. Either negative or distant tumour detection will be worse news.

[Hailwood in reply to Justfor_]

That’s my thought as well. The recent study gives a very disheartening 3 year prognosis if there are distant Mets. It’s all conjecture until Thursday and here the sun is shining, the Kawasaki has a new Maxton shock and fresh tyres, so everything is good. Thanks for the information

[Blackpatch in reply to Justfor_]

Thank you very much for posting this paper - I had seen the earlier ones describing the early part of the study, but not the 3 year results. I'm extremely fortunate to be in the "negative PSMA" group, despite being pT3b with a short doubling time post-BCR. Given the pT3b and a very high Decipher score, I went ahead with eSRT (at PSA=0.12) + 12 months ADT - and so far, 25 months post-eSRT, my PSA remains undetectable.

It's quite surprising to see that only 11% of negative PSMA scan men adopted a similar course of action, given I was making my decision in the "Australian PSMA treatment" setting characterised by the PSMA results in this paper. This really proves the point often made on this forum that we each need to remain vitally interested in our own treatment strategies - we are most certainly our own best advocates. Despite being treated by people involved in the work reported in this paper, after receiving the negative PSMA result, the path of least resistance for me would have been to put off eSRT + ADT - and from the results presented, I would almost certainly have fairly quickly moved beyond where a durable "cure" would have been achievable.

All that said, it would be vert interesting to see if the negative PSMA group in the paper who report FFP at 30 months still continues in this state - progression many years post-eSRT is reported by some in this forum, and is a continuing concern for many, I'm sure.