More proof that results of SBRT are equivalent to IMRT (yet faster and cheaper)

[Tall_Allen]

I am pleased that SBRT was my choice of primary therapy 8 years ago. The randomized comparisons are showing that it is at least as beneficial as IMRT, but it takes only 4 or 5 treatments and costs a lot less too. Here are the results of two more randomized clinical trials so far:

pcnrv.blogspot.com/2019/02/...

[19tarpon47]

x2 on SBRT. It was my choice of primary treatment 18 months ago and all has gone well so far with little to no side effects. Honestly, the preparation for the treatment was in my opinion far worse than the treatment. So far so good and my PSA has been bouncing along in such a way that mirrors what the literature says is best for long term outcomes. PSA prior to treatment was 7.30 followed in 3 month intervals after treatment of 2.50, 1.64, 1.76, 1.78, 3.78, and at 18 month post-treatment 1.10. I'm happy....

[cesanon]

Tall_Allen,

I thought that the difference between SBRT and IMRT was that SBRT was more precisely targeted.

Is my understanding in error?

[Tall_Allen in reply to cesanon]

That's part of it. What most people mean by SBRT is extreme hypofractionation (usually 7-8 Gy per fraction). Because of the high dose, it has to be very precisely targeted, not just from one treatment to the next (inter-fractional tracking) like IMRT, but also within each treatment (intra-fractional tracking). CyberKnife is a robotic "step and shoot" way of doing that, with tracking before each "shot." I was treated on a VMAT system, with image alignment before each half-arc.

Interestingly, in the Scandinavian RCT they used a much less precise platform without intra-fractional tracking known as 3D-CRT, but they got very good results anyway. They used a slightly lower dose per fraction (6.1 Gy) and 7 fractions, but I'm surprised the toxicity wasn't much worse. Good planning can make up for some of the deficits.

[cesanon in reply to Tall_Allen]

Hmmm I went to Datolli Clinic in Florida of IMRT where they use a lot of treatments with a lot of radiation. But he did seem to be very obsessed with precise targeting. Even to the extent of tracking my breathing.

I wonder if what I got was sort of a hybrid of the two.

[Tall_Allen in reply to cesanon]

"Respiratory gating" (tracking of breathing) is actually a common feature in advanced linacs. It's very important in lung RT. As it turns out, it's not a very important part of primary prostate radiation. Breathing has little to do with pelvic organ motion (the diaphragm is above all that) - a full bladder lifts the bladder away from the prostate and and weights it in place. An emptied rectum with no laxatives or enemas prevents excess bowel motion. Those are the two main things.

Dattoli used to be opposed to any kind of hypofractionation (I have no idea if he's changed his mind since). I know he used a VMAT system for IMRT (similar to the one my RO uses for IMRT and SBRT - there is no such thing as a hybrid- you either do intrafractional tracking of the prostate (with fiducials or radio transponders), or you only do interfractional tracking (with fiducials or radio transponders). Interfractional is fine for IMRT where a little bit of miss here or there isn't critical.

[Sherpa111]

How would an ideal candidate for this form of treatment present?

[Tall_Allen in reply to Sherpa111]

Any man with low or intermediate risk PC (with expected life of at least 10 years) is a good candidate. Of course, low risk men should consider active surveillance. Use of SBRT in high risk men is experimental and in ongoing clinical trials.

[Hidden]

Is SBRT commonly available? Is it offered by Mayo or Cancer Treatment Centers of America? How do I find a practice that offers this?

[Tall_Allen]

I don't think Mayo does - I have no idea about CTCA. It is widely available, but like every other treatments, there are specialists. Most often used platform is CyberKnife. Where are you located?

[KSK54]

Allen

I am thinking of taking another chance of salvage radiation. This time of whole pelvic region for a possible last chance of cure, after failed prostatectomy(2010)and failed salvage radiation (2017) to prostate bed only.

Present PSA 0.085. Increasingly steadily for the last one year.

1.Should it SBRT or IMRT?

2. Can you recommend 2/3 top RO and centres for this?

Thanks.

[Tall_Allen]

(1) Probably IMRT to be safe. This is usually 50 Gy at around 1.8 Gy each treatment. Make sure they use the expanded pelvic lymph node region:

pcnrv.blogspot.com/2017/02/...

(2) Any good RO who has a modern linac can do it. Because it involves about 5-6 weeks of treatments, you probably want to stay close to home. Where are you located?