They Told Us Their Was No Benefit to IADT Compared To ADT in The Risk of CRPC

[gusgold]

Unless I am reading this study wrong there is a big benefit in terms of RISK of developing CRPC at 3 years

Gus

ncbi.nlm.nih.gov/pubmed/269...

[PaulC2]

You are indeed reading the writeup correctly, but studies are tricky things.

It seems to me that we should trust this sentence:

> PCA3 score status at baseline was the only variable associated with

> a higher risk of progression to CRPC in both the intermittent and

> continuous ADT groups; [...]

If the only dependent variable was PCA3 — that is, if PCA3 was the only variable being tracked and measured to see how it varied according to changes in the independent variables —, then we simply don't know how the population came to be divided into CADT and IADT subgroups.

For example, it's possible that the CADT guys started out with longer time on ADT, and/or much sicker than, the IADT guys, in which case one would expect them to progress faster.

But as I say, studies are tricky things. Having read a lot of them, I think these authors were trying to send a hidden message that the CADT vs IADT controversy needs further investigation. They can't claim this in a peer-reviewed paper, since they didn't properly control for it; but I think they may be hinting at it nonetheless.

[JoelT]

As Paul indicated the study was not designed to evaluate intermittent ADT vs continuous ADT. Its conclusions are only that PCA3 status was the "ONLY" variable associated with an increased risk of developing CRPC, not the ADT schedule.

Joel

[AlanMeyer in reply to JoelT]

I think Joel nailed it here. I don't think this was a study of continuous vs. intermittent ADT. It wasn't even a study of how PCA3 blood levels changed over time (they only measured PCA3 levels once for each patient, at the beginning of his ADT treatment.) I think the purpose of the study was to find out if PCA3 levels at the start of ADT could predict who would fail ADT (i.e., become "castration resistant") earlier than others.

Their conclusion was Yes, PCA3 levels do predict likelihood of failure. If you have a PCA3 level greater than or equal to 35 at the time you begin ADT, you are more likely to fail ADT within 3 years than those whose PCA3 level is lower. This appears to be true whether you are on continuous or intermittent ADT.

Bear in mind, of course, that the relationship between PCA3 and ADT failure is not absolute. Some men with high PCA3 levels might still do well on ADT after 3 years and some men with lower PCA3 levels might fail ADT within 3 years anyway. All they concluded is that a high PCA3 level makes it more likely that ADT will fail earlier.

I hope that clarifies things (unless I got it wrong and muddied them up )

[Cantabrigian51]

As PaulC2 pointed out, we don't know how the men were divided. The paper says: " Patient treatment and assessments were at the investigator's discretion", so the division was not random. Perhaps the Gleason scores differed between the groups.

[AlanMeyer in reply to Cantabrigian51]

Yes. In general, men are only offered intermittent therapy if their response to ADT is really, really good. So it's not surprising that the number of men on continuous ADT who became castration resistant in this study is higher than the number on intermittent. It would require an entirely different study design to see if continuous or intermittent ADT is better.

[20PeteG16]

Gus and friends,

I am encouraged by this article. My hope is that further large scale studies are undertaken. I am a poster patient for IADT and active surveillance, in my opinion.

With a Gleason of 4+4, in 2008 I choose cryosurgery by Dr. Stephen Scionti. No ADT after surgery until PSA doubled and MRI indicated cancer in lymph nodes in 2010, Casodex and three applications of Lupron at four month intervals dropped PSA undetectable. In 2016 PSA doubled to above 4.0 Tomorrow I start Casodex again in anticipation of Lupron on 16 February nine years to the day prostate cancer was diagnosed.

I wish all patients the quality of life I have been enjoying, look forward to more effective treatments and possibly a vaccine.

PeteG.

[Hidden in reply to 20PeteG16]

I got tagged Gleason 8 too. I opted for HIFU. My six month eligard (ADT) shot is still in effect for a month or two more. I'm not going to do any more ADT unless and until a rising PSA suggests that I need to. It is easy for Urologists to prescribe 2 or 3 years of ADT. They aren't the ones dealing with the QoL effects. CT and bone scans indicated no metastasis.