Even with RT as primary therapy, PSA can go directly to undetectable

This seems to have been happening to me (see signature below). A conversation with my uro has shed a little light on this.

Like I assume most of us have done, I had understood that for men with radiation-as-primary treatment, the expectation was that their PSAs in post-treatment would be lower, then gradually over months or even years taper off to lower and lower values, with the possibility of a bounce somewhere along the way, but eventually get to the point of being stable at some low number (but only after time).

In my own case after receiving IMRT last year I thought this would be the case, and I had been surprised over the past year and several months that my post-treatment PSAs have so far all been in the undetectable range. Granted, I had also had HT (Lupron) before, during and after the RT, but the HT effect should have worn off over time, and certainly not have influenced my most recent test.

When my uro phoned me recently to tell me my most recent PSA result (a nice touch on his part, BTW, as he likes to call his patients personally when the news is good), I asked him about this phenomenon. He told me that in his own practice he sees this PSA-straight-to-undetectable event happen in maybe 5-10 % of his RT-as-primary patients. He said that in most of these cases the undetectability will last for perhaps the first few months following RT, then a regular, but very small, PSA level will finally start up and continue. But he added that he has also seen a few patients where this effect has lasted a couple of years or more. He said he has no theory as to why this might be happening, as he had not seen a common denominator among these patients.

When I asked him what might be causing this to happen in my case, he paused for moment (I could hear papers rustling over the phone, so I guess he was looking at my record or chart). He then suggested that since I had received a pretty substantial radiation dose (81 grays) over 45 treatments, that this may have been enough to "nuke" (as he put it) my prostate, and that more or less knocked it flat on its back, so to speak, and left it in no mood to start putting out PSA for a while, at least not in any detectable quantities.

But then he added, although he wasn't sure why it would happen, that my prostate might get itself going again at some future point, and I would eventually have a detectable PSA again.

Here's an article that discusses this straight-to-undetectability phenomenon for RT-as-primary guys:

www.fccc.edu/information/news/press-releases/2009/2009-11-01-astro-horwitz.html

It's interesting to note that doing a little math with the figures cited in this article gives about a 12 % rate for this kind of thing, roughly in agreement with the 5-10 % that my uro quoted.

Anyway, I'm making this post to report that apparently this phenomenon does exist (I'm an example, apparently), and it might be of interest to those contemplating doing RT.

Very interesting, and good for you! Thanks for sharing that.

I'm still on ADT2 for 18 more months, so even though the immediate post-RT PSA level was <0.1 we won't know for a long time what the RT actually did.

Irmaly's husband is the only one I recall with an undetectable after 1 lupron shot and radiation. I realize that the prostate's normal cells will continue to produce some psa but to me this was an unusual event. I don't recall the details but hope that there is no chance of recurrence ever.
Bill

I am thankful that you are in this exclusive little club with such great results, hope it stays that way for you for many years to come. Interesting subject, never heard this discussed before.

David

Can't cite the reference, but recently I read a way that radiation can prevent future PCa from developing in the residual prostate tissue. It greatly reduces the ability to form new blood vessels (angiogenesis). New tumors need new blood supply, and if they can't get it the cells don't survive long. I suppose that's one reason salvage RT is preferred to be done after healing from surgery. It is reputed to slow or stop further recovery in the irradiated tissues.

My RO said he rarely sees RT failure due to new tumors in a prostate after radiotherapy. It's typically from pre-existing micromets developing elsewhere.

81,
I think the immediate undetectable reaction is more due to the Lupron than the radiation itself. HT should drop psa to undetectable levels, <.05 by itself fairly quickly in intermediate grade patients since we are still dealing with mostly androgen dependent cells. As you can see from the posts all that have had an immediate reaction also were on HT. I was .02 before I even started radiation. Without the HT I think we would have seen a more gradual drop which is common with just radiation.
Redwing,
Dattoli has some data for high risk patients that show reoccurrence after 6 years is very rare with radiation, out of 1400 consecutive high risk patients all reoccurrence were due to systemic disease and not local, confirmed by biopsy, which supports the "fallow" prostate theory of radiation. Whereas 10% of all surgical recurrences occur after 10 years.