SRT Confusion~Keep it Simple

Bob is preparing for SRT (marker implants scheduled for the 17th). The more I read on SRT the more confused I get. I've been researching since 2014, maybe my brain is fried and that's why I'm not getting it. I've read all that I can that TA has posted, links included, and I'm still confused. Bob's current PSA .26, he did have 0 after surgery so from 0-.26 in 2 1/2 years. Pre surgical PSA 4.1 and he had a positive margin. I need someone to explain to me SIMPLY exactly how the dosage works. His first visit doc had said 66 GY for treatment (that's when his PSA was .13) this newest visit doc is suggesting 72 (he may have said 70.2 but I have written down 72) over 40 treatments. Isn't the norm 66 GY? Especially someone that had the positive margin? Also with his past history of Ulcerative Colitis wouldn't it be prudent to err on the side of caution with 66? I don't even know if 72 Gy is considered a "high dose". Is there a difference between toxcicity in the 66 and 72? To me it seems the higher the dose the more likely the complications but again I will state that I have no understanding of what I am reading. He will also be doing 6 months firmagon which the doc. didn't even mention until I brought up the question of better results using the two together. Any thoughts? Someone please set me straight. Thanks.

From what I have read the optimal dose has not been well defined but it should be at least 66 Gy. Survival improves per added Gy but with dose escalation the rate of severe side effects increases. I have seen that up to 76 Gy have been used. With the high PSA you have a high dose is probably warranted.
Not sure if the used RT machine (old or new) impact toxicity but I doubt it should.

I knew some people didn't have to have markers but I didn't know it was because of a more up to date machine. We are at the most advanced place in our state. There are very few places that even offer IGRT in our state. Another oncologist we saw last year (that was closer to us) even said he can't compete w/ where we are using. When you live in one of the poorest states in the U.S. and don't have money to travel for treatment you take what's available and hope for the best.

I'm glad he will be getting 72 Gy. That would be 40 treatments at 1.8 Gy each, so that makes sense. Here's why it's a good idea:

[url]https://pcnrv.blogspot.com/2016/11/dose-escalation-for-salvage-radiation.html[url]

After you've read it, tell me what it is you don't understand. In simple terms, it says:

• 66 Gy is not enough
• For every additional +1 Gy, recurrence-free survival goes up by +2 percentage points
• So increasing the dose from 66 Gy to 72 Gy (+6 Gy) can reasonably be expected to increase recurrence-free survival from about 50% to about 62%
• Acute grade 2 or 3 rectal toxicity was 17% at 64 Gy and 18% at 70 Gy in a randomized clinical trial - so, no difference among patients treated recently (since 2011).

With today's best machines, rectal toxicity is usually not a problem. It is not at all true that fiducials are used with older machines. In fact, the use of fiducials with cone beam CT to use them with most likely means a very up-to-date machine is used there. The use of fiducials is controversial - some ROs use them with SRT, some prefer to align visually on soft tissue.

Thanks TA, this was actually one of the articles I had read that you had linked when I was researching. 1. What is the meaning of chronic vs. transient toxcicity? 2.Quoted from article "At the top treatment centers, radiation oncologists routinely deliver doses as high as 70 Gy, but seldom higher." 2. So what would be the logic in going up to 72? I'm assuming by the article that this is a safe dose but if even the top centers are doing 70 are we pushing it by doing the 72? Or does that go w/ what you were saying for each +1 GY survival goes up by 2 percentage points so why not if it's not going to have any more SE's.

@Jeff, I think we discussed this in an email last year but please refresh my memory what medication you were taking for your UC during radiation. Bob's gastro recommends Lialda but that stuff was very expensive last time he was on it (he hasn't been on it in a while) so I'd be interested what you were on and did they increase your dosage during treatment?

"1. What is the meaning of chronic vs. transient toxicity?"

Chronic means ongoing side effects; transient means the side effect shows up but then fades away.

"2.Quoted from article "At the top treatment centers, radiation oncologists routinely deliver doses as high as 70 Gy, but seldom higher." 2. So what would be the logic in going up to 72? I'm assuming by the article that this is a safe dose but if even the top centers are doing 70 are we pushing it by doing the 72? Or does that go w/ what you were saying for each +1 GY survival goes up by 2 percentage points so why not if it's not going to have any more SE's."

Now you're getting it

ARangel14,

I had SRT 3 1/2 years ago. My treatment was 39 session at 1.8 grays (70,2) using a IGRT/IMRT and had zero side effects during treatment and afterwards. It was a non-event for me. I didn't have judiciaries, but three very small tattoo dots, on on each hip and one below my navel on the pubic area. Each session the rad techs would take a CT and make any adjustments on position, bladder size, and bowel.

I got up every morning at 4:30 am to go to work (very active at work), and on the way home each day I stopped for my treatment. Usually I was in and out of the radiation center in about 15 minutes.

Just a little side note. Went to pick up Bob's Lialda today. Cash pay is $1,250 for a months worth. Thankfully he's already on 100% major medical so it cost us nothing but just a heads up if you ever have to take this for UC. That's crazy. I don't know if they prescribe it for men who have problems w/ colon during radiation that don't have a history of UC.

Thank you Beth, you've been w/ us almost from the beginning. Never knew this road was going to be this long. I thought they'd take it out and we'd be done. You know PC, surprises await around every corner. (((Hugs))) to you.

Hi
All the best to yr hubby SRT.
Just watch for the requirement on the table.
full badder & no or minimum gassy food

✋️