MRI-Guided ViewRay for Salvage Radiation

[Rams91]

Looks like I'll be soon heading for 6-7 weeks of IMRT salvage radiation. Has anyone been treated or aware if MRI-guided linacs such as the Mridian Viewray offer an advantage over CT-guided ones when it comes to post-op salvage radiation? With prostate gone, it seems a higher portion of the bladder and rectum will be in the radiation target area when it comes to salvage therapy, and hence causing more side effects. Can MRI-guided equipment effectively reduce the target area while achieving the same or better oncological outcome together with less side effects? Thanks.

[Tall_Allen]

Never tested against VMAT at salvage. It probably makes little difference.

[Rams91 in reply to Tall_Allen]

Thanks Allen. I thought as much but noticed in a recent Q&A that Cornel is running trials doing only 5 session post-op SRT treatments on ViewRay.

[Tall_Allen in reply to Rams91]

Yes - trials only.

[Rams91 in reply to Tall_Allen]

Hi TA, if I remember correctly, you were one of the early participants in having SBRT as a primary RT. Do you recommend joining the SBRT trials for salvage post-op? It's half the radiation of conventional IMRT, only 5 sessions but obviously LT results still unknown.

[Tall_Allen in reply to Rams91]

I always encourage patients to participate in clinical trials. Yes, I had SBRT when it was still in clinical trials - now, it's SOC. In fact, I'm doing a clinical trial now for an unrelated ailment.

[Rams91 in reply to Tall_Allen]

Hi TA. I came across one of your blogs in 'prostatecancerinfolink.com' in 2018 discussing salvage SBRT after radical prostatectomy. I know probably MRI imaging for adaptive planning and intra-tracking of OARs was not available then as it is today. I was wondering if you have any recent updates on the subject, specifically on the risks of excessive toxicity (such as on location of anastomosis scar tissue) caused by ultra hypofractionation in salvage setting that was talked about in your article. I know the UCLA phase II trial is still ongoing, but phase I seemed to suggest lower incidences of short-term GI and GU toxicity.

[Tall_Allen in reply to Rams91]

I had MRI imaging for planning, actually, CT/MRI fusion - it's been available for a long time. Intra-fractional tracking has always been done for SBRT - it's essential. Adaptive planning is still experimental, and is rarely done.

This article is the one you're referring to, I assume:

prostatecancer.news/2018/01...

Since then, this has been published:

redjournal.org/article/S036...

[Rams91 in reply to Tall_Allen]

Thanks. I was hoping there would be a more recent update on late term side effects and efficacy to convince me to participate in the EXCALIBUR trial.

[Concerned-wife in reply to Rams91]

my husband traveled from out of state to Cornell or this treatment..not post op. Originally we thought he’d be in a trial but they treated him outside the trial. Perhaps contact Dr Nagar for a consult. We like and admire him.

[OldVTGuy]

That’s a good question because I don’t suppose you’ll get fiducial markers to aid the IMRT.

[tsim]

It certainly has shown very good results in reducing latent radiotoxicity and urinary effects from initial treatment, not much info about salvage though. I can't believe it would make things worse.

[Piano777]

Recently released clinical trial indicates MRI-guided has significantly less side-effects than CT guided for initial treatment. As mentioned earlier, doesn't comment on salvage, but would imagine similar benefits.

Study January 12, 2023: doi.org/10.1001%2Fjamaoncol...

[dlste353]

I don’t know whether Mridian is ever used for salvage radiation. But I just offer this to help you put your mind at ease. I had 37 rounds of salvage IMRT with almost zero side effects. No urinary difficulties at all, and very slight change in bowels for only a few weeks. I think it’s important to find the best RO you can find.

[j-o-h-n]

SpaceOAR Hydrogel™ - Temporarily Creates Space.

Good Luck, Good Health and Good Humor.

j-o-h-n Thursday 07/20/2023 7:42 PM DST