SBRT Late Stage Radiation Toxicity-Anyone Experienced These?

What you can do to offset these issues is to make sure your doctor uses a MRIdian SBRT machine (or equivalent). The MRI guided SBRT uses a much finer beam that affects less tissue near where Radiation is needed. You can also get a SpaceOAR or equivalent to protect your rectum.

I have not really heard of people complaining about long term after effects of SBRT, at least there’s not been a major discussion from people that feel they are affected, like you describe. I had seven weeks IMRT radiation and the only issues I have after 11 years is some incontinence.

Radiation cystitis AND radiation proctitis for me after 60 gy of SBRT.

Both are mild, according to imaging (18 and 24 months later), but the symptoms of the cystitis suddenly became a big problem for me a year after I finished radiation, and took 5 months to get back under control. Now they're both just mild inconveniences, at worst.

Thanks @jeffmarc! I'm always amazed at the depth of your knowledge and you unwavering commitment to help others! You're an inspiration!

@northoftheborder, thanks for sharing your experience! It's one thing to read a clinical study. It's another to get feedback from someone who has walked the path ahead of you!

gsd: I agree with @jeffmarc

I had the Mridian radiation machine with a built in mri so the margins around the cancer were 2 mm instead of 3-5 for most other non-built in mri machines. This meant less side effects and toxicity. I had 5 treatments in February of 2023. My Gleason was 3+4 and a 11.2 psa. I have had little or no side effects. The Elekta unity machine is another built in MRI machine.

Check out the Mirage randomized trial comparing side effects and toxicity between built in Mri and non-built in mri radiation machines.
https://www.urologytimes.com/view/mirage-trial-margin-reduction-with-mri-guided-sbrt-reduces-toxicity-vs-ct-guided-sbrt

Short answer, not yet, then again, I'm only 23 months out from my SBRT.

I've had radiation three times:

March 2016 SRT 39 IMRT 70.2 GYa
July 2017 WPLN 25 IMRT 45 GYa
April 2023 SBRT 5x8 40 GYa

Side effects, nada..a tribute to my radiologist (she's done all three) and her team and the planning software as well a delivery technology.

Kevin

Thanks, Thanks, @bens1! I've downloaded the 2-year data report. Looks interesting! I appreciate your willingness to share and thank you for reporting your post-treatment experience! Much appreciated!

Thanks for your post treatment report, Kevin! By the way, I'm in awe of your treatment history chart!

Guy

Great question GSD! A definitive answer to your question is some years away. I'll make a few observations and what I think is likely to emerge as more data becomes available.
1. One thing to remember is that PACE-B was concluded over 5 years ago in a different county and while the protocol looks similar it may not be identical to current treatment/hardware being used here today.
2. That said, there does appear to be a small, but real increase in late GU complications with SBRT as you've noted.
3. As Ben pointed out, all SBRT isn't equal. "Regular" SBRT typically uses 5 mm margins except posteriorly where 3 mm is common. Margins in PACE-B were 4-5 mm except posteriorly where they were 3-5 mm. MR-Guided SBRT is typically uses 2 or 3 mm margins and is the most likely mechanism for any benefits over regular SBRT (i.e., not the adaptive planning or continuous monitoring).

My best guess, which I posed to the GU section chief at arguably a top U.S. cancer hospital, is that when all the data is in, we will know that SBRT (Cyberknife, Proton, etc), while more convenient, does carry a small increase in late GU complications compared to moderately hypo-fractionated treatment of 28 sessions. With MRI-guided RT (Electa or MRIdian) the complication rate is likely to be equivalent to 28 sessions while maintaining the convenience of only 5 sessions. FWIW, the "top name" radiation oncologist agreed and said that's also what he thought.

Therefore, you won't be surprised that when I'm asked for a recommendation about SBRT, my standard response is if there is a choice between 28 sessions and 5 sessions on a standard machine, AND you have the time, I'd take the 28 sessions. If you have access to a MRI-guided machine, then I'd go with the MR guided strictly for the convenience.

FYI, I had 2 mm margins on a MRIdian machine for favorable intermediate disease.

Thoughtful post midatlpatch. I came to the same conclusion, I was worried about GU effects and believe as you the 28 sessions is preferable based on data I can find. I did proton therapy with Spaceoar for 28 sessions. Agree that MRI guided trumps other treatments. Note of caution, no free lunch as proton has higher rectal complications, Spaceoar is essential to reduce risks to 5% or so.