Duration of ADT w/SRT

Ok, setting aside for a moment that a year ago, I thought ADT was the company that monitored my alarm system, and SRT was a designation that Dodge gave the sportier versions of some of their vehicles.....

So, in discussions about how we might go about SRT, I've gotten differing views on the length of ADT that would be done at the same time (well, really starting before RT, and continuing after for some period.) Independent of each other, my Uro and RO think that a six month course of Lupron is sufficient to gain whatever additive benefit it might add to the RT process. My MO wants to do at least a year, and actually would prefer two years if I was willing to do it. For the record, I feel lucky in that I have very experienced people in each of these positions offering me the benefit of their experience, and I have a great deal of faith that each is quite well versed, specifically in PCa, with a very strong interest in MY well being (note, these are all HMO docs, so the pay for services "bias" that private practice docs may or may not have is not really in play here.....yes, I know that's a huge generalization, but really wanted to just take that whole conversation off the table!)

So, here's my take on this scenario. If I decide to do SRT, I believe that I have been convinced by my medical team, and my own research, that there is a benefit to doing a course of ADT simultaneously. Where I'm having trouble with my MO's desire for a longer run of ADT is here. If you assume that SRT is potentially curative (no need to argue this, just assuming it for sake of my very long-winded question), and you assume that ADT is NOT a curative treatment (at best it weakens cancer cells making them more susceptible to RT AND starves them of the testosterone fuel.....at worst, it just does the latter for some period of time until it doesn't), then why would it make any sense to do ADT for any longer than six months? In my mind, it seems that in order to determine if RT has "cured" someone, you need to stop ADT so that subsequent PSA readings are "true" (i.e.: if RT worked, PSA will remain undetectable, if RT did not work, at some point, PSA will begin to rise.)

At some point you have to drop the ADT to really know, and given the quality of life impact (potential), and side effects of long(er) term use, it seems to me that dropping it after six months makes more sense. My current opinion is that stopping Lupron is the only way to get to a point where your PSA monitoring is giving you a true reading of where you stand.

Am I nuts? What am I missing? BTW, I have thought of the scenario where RT didn't work, therefore, being on a longer initial course of ADT has some suppressive benefit of (hopefully) slowing any progression of remaining cancer cells.

I'm very curious about your thoughts on this topic within the given scenario. Again, am I missing something?

Oh, and I'm posing this question to my MO this week, but thought I'd gather some anecdotes/opinions from the HW brain trust for starters. :)

Thanks in advance!

Rich G.

I always hesitate to answer questions like this because Tall Allen always has better information than I do. I have joked before that I play the same role here that Gabby Hayes did for Roy Rogers. I arrive at the scene, give the principals someone to talk to to establish the situation, provide a bit of comedy relief and wait for Roy to ride in and set things straight.

But, while we wait, I understand your theory that most of the benefit of adding ADT to radiation comes from sensitizing the cancer to the radiation -- making it more effective -- and that continuing the ADT for a long time after the primary effect of the radiation ends can get into diminishing returns. I suppose you are right about that. If you were to draw a graph of the curative benefit of adding a period of ADT to salvage radiation (as a function of the duration of the ADT) I expect you would see some sort of sigmoid where the benefit was rising briskly between three and six months and then started to level of at an asymptote. The question is, where is the shoulder of that curve?

My answer would have two parts -- first establishing that we are talking about high-risk disease for which your Gleason 8 probably qualifies: Part one of the answer would be to point out that radiation damages the DNA in the cancer cells so that, later, when it tries to divide is can't and it dies. If you think about the PSA results of men who have had radiation as a primary treatment you will remember that it drops off over the course of a few years with bumps and bounces here and there to keep the process exciting. It takes a while for the cancer cells to get around to dying and that is probably the point where the ADT has much of its effect. The second part of my answer is that, while theorizing is a good way to understand the data, it has to take second place after the data itself. There isn't a lot of data for the optimum length of ADT (and I think I am remembering primary treatment results here, not salvage) but I seem to recall that 18 months was sort of a sweet spot.

That's all I've got. Hopefully Roy will be along in a bit...

@Peter - I think you may be selling yourself a bit short there, and I appreciate you jumping in to voice your opinion for sure! I agree, data would be great, only I am not certain that there is conclusive data that exists (as you pointed out.) Even my MO said there are three studies that most "in the know" refer to (I didn't get links/names) that look at the effect of 1 year, 2 year and 2 year+ of ADT versus not having any ADT. Each shows that ADT has beneficial results, though they don't compare to each other, so can't reliably be used in a fashion to determine which length is best. I will ask her for the study names so that I can verify that they are targeted at benefits of ADT with Radiation, and if that includes primary radiation treatment as well as salvage. One thing that I can bet, my age group is likely to be under-represented! :)

@Bohemond - Interesting....all three of my docs never mentioned anything other than Lupron. I'm familiar on a surface level with Casodex, so will add that to my list of things to discuss. Thanks!

Keep it coming, folks! :)

Rich

@Peter - Thanks for the links, some good stuff to read there later today. Looks like there really isn't any study data that has deeply looked at Salvage + ADT, so perhaps the best guide is inferences from RT (primary) + ADT, and further counsel with my medical triumvirate! :)

Rich

@TA - Thanks, Allen, great stuff. I looked at the UMich study last night. In the absence of specific research/study data to go on, I'm starting to lean toward at least 12 months, possibly 18-24 (...and, I have 12 months to do more research!) On the mechanics of the RT, I don't have those details, so I will verify with my RO what the plan is regarding the imaging and radiation process. I do know that he's looking at 72 Gy for me.

Thanks for the input!!

Rich