Prostate SBRT in NYT

[Chartreuse Wombat]

https://www.nytimes.com/2017/03/20/health/prostate-cancer-sbrt-radiation-therapy.html?_r=0

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[Gfunk6]

Interesting article, thank you for sharing. When I was in training, the SBRT schedule we used for prostate cancer mimicked the one we used for definitive HDR monotherapy. While trials are necessary to ascertain the true answer, I don't think this type of treatment is as unproven as this article states.

Also, prostate SBRT bends the cost curve and gives a powerful advantage > radical prostatectomy versus 5.5 - 8 weeks of fractionated XRT.

 

[evilbooyaa]

All the nay-sayers are going to say that you have to do something for 10-15 years before you could potentially even discuss it replacing standard fractionation.

 

[FistLength]

Wouldn't seed implant be even better, considering it is one and done and there is already research behind it.

 

[medgator]

All the nay-sayers are going to say that you have to do something for 10-15 years before you could potentially even discuss it replacing standard fractionation.

I don't see how that's unreasonable for something like prostate CA. Toxicity prob a bigger concern than in breast imo, plus we have better long term data for hypo fx in breast for something like skin/soft tissue reactions vs more serious bladder/rectal injury

 

[seper]

what's the best paper on this (with the longest follow up I mean)?

 

[BobbyHeenan]

I've contemplated offering this at our cancer center, but I think I'll wait until a big phase II or III trial (RTOG or alliance, etc) open up and then participate

The best papers I think are the Stanford experience (King is the first author I believer) with 7.25 Gy X 5. Historical older trials (SHARP) used a slightly lower dose, and as I recall had more biochemical failure than I would expect for mostly low and intermediate risk patients. UTSW used higher doses (around 10 Gy X 5 as I recall - based on HDR modeling) with good early clinical results.

I'm not sure anyone knows an ideal dose/fractionation scheme yet, and as mentioned long term follow up is somewhat lacking. I personally don't want to do it off trial so I'll await a phase II or III that I can enroll on.

 

[Chartreuse Wombat]

I've contemplated offering this at our cancer center, but I think I'll wait until a big phase II or III trial (RTOG or alliance, etc) open up and then participate

The best papers I think are the Stanford experience (King is the first author I believer) with 7.25 Gy X 5. Historical older trials (SHARP) used a slightly lower dose, and as I recall had more biochemical failure than I would expect for mostly low and intermediate risk patients. UTSW used higher doses (around 10 Gy X 5 as I recall - based on HDR modeling) with good early clinical results.

I'm not sure anyone knows an ideal dose/fractionation scheme yet, and as mentioned long term follow up is somewhat lacking. I personally don't want to do it off trial so I'll await a phase II or III that I can enroll on.

NRG has completed a Phase II that was reported at ASTRO and should be published soon.

NRG will soon open a randomized trial comparing 70 Gy in 28 fractions to SBRT for intermediate risk patients-Dr Ennis mentioned this in the NYT article

 

[seper]

King's paper did have some worrisome side effects, as I recall.
What's that NRG ASTRO abstract? (sorry, don't know a good way to search for ASTRO abstracts).

 

[Chartreuse Wombat]

King's paper did have some worrisome side effects, as I recall.
What's that NRG ASTRO abstract? (sorry, don't know a good way to search for ASTRO abstracts).

http://www.redjournal.org/article/S0360-3016(15)26641-2/fulltext

 

[MegaVoltagePhoton]

I've contemplated offering this at our cancer center, but I think I'll wait until a big phase II or III trial (RTOG or alliance, etc) open up and then participate

The best papers I think are the Stanford experience (King is the first author I believer) with 7.25 Gy X 5. Historical older trials (SHARP) used a slightly lower dose, and as I recall had more biochemical failure than I would expect for mostly low and intermediate risk patients. UTSW used higher doses (around 10 Gy X 5 as I recall - based on HDR modeling) with good early clinical results.

I'm not sure anyone knows an ideal dose/fractionation scheme yet, and as mentioned long term follow up is somewhat lacking. I personally don't want to do it off trial so I'll await a phase II or III that I can enroll on.

UTSW's trial actually had terrible outcomes -- the dose they went to (10 Gy x 5) was too high.

Stereotactic body radiation therapy for low and intermediate risk prostate cancer-Results from a multi-institutional clinical trial. - PubMed - NCBI
Predictors of rectal tolerance observed in a dose-escalated phase 1-2 trial of stereotactic body radiation therapy for prostate cancer. - PubMed - NCBI

The reported rate of late grade 3 toxicity isn't very high in any other series. Katz has reported very favorable long-term results Quality of Life and Toxicity after SBRT for Organ-Confined Prostate Cancer, a 7-Year Study. - PubMed - NCBI

 

[BobbyHeenan]

UTSW's trial actually had terrible outcomes -- the dose they went to (10 Gy x 5) was too high.

Stereotactic body radiation therapy for low and intermediate risk prostate cancer-Results from a multi-institutional clinical trial. - PubMed - NCBI
Predictors of rectal tolerance observed in a dose-escalated phase 1-2 trial of stereotactic body radiation therapy for prostate cancer. - PubMed - NCBI

The reported rate of late grade 3 toxicity isn't very high in any other series. Katz has reported very favorable long-term results Quality of Life and Toxicity after SBRT for Organ-Confined Prostate Cancer, a 7-Year Study. - PubMed - NCBI

Yeah, I was specifically referring to the early publication regarding early clinical results - Phase I dose-escalation study of stereotactic body radiation therapy for low- and intermediate-risk prostate cancer. - PubMed - NCBI

I feel like for prostate SBRT it's reasonable to wait for the late toxicity publications and this UTSW experience is the perfect example of this - with initial 2011 JCO paper showing no dose limiting toxicity and subsequent follow up paper 5 years later showing concern for late toxicity.

 

[Chartreuse Wombat]

Yeah, I was specifically referring to the early publication regarding early clinical results - Phase I dose-escalation study of stereotactic body radiation therapy for low- and intermediate-risk prostate cancer. - PubMed - NCBI

I feel like for prostate SBRT it's reasonable to wait for the late toxicity publications and this UTSW experience is the perfect example of this - with initial 2011 JCO paper showing no dose limiting toxicity and subsequent follow up paper 5 years later showing concern for late toxicity.

Perhaps but length of follow-up in UTSW experience is confounded by dose. There are larger experiences with longer follow-up using doses of 35-37 Gy (rather than 50 Gy) and no fistulae reported.

 

[OTN]

50 Gy x 5 proved to be too much to the rectum, but IMO the data for 40 Gy in 5 fx is looking good. I only started offering it this year to avoid problems with being an early adopter- namely running into rectal toxicity from overdosing.

 

[medgator]

50 Gy x 5 proved to be too much to the rectum, but IMO the data for 40 Gy in 5 fx is looking good. I only started offering it this year to avoid problems with being an early adopter- namely running into rectal toxicity from overdosing.

Are you feeling pressure to offer it to remain competitive in your market?

I know some people are doing it as a differentiator for their practice in more saturated areas.

I still not quite there yet, personally and fortunately haven't really had a lot of patients ask for it...

 

[Gfunk6]

Hypofractionation and SBRT/SABR/SRS are the future of radiation oncology. Not only is technology pushing us in this direction but reimbursement as well. Once capitation comes, and have no doubt it is coming, 1.8 Gy per fraction will die a quick death for prostate cancer.

 

[Chartreuse Wombat]

Hypofractionation and SBRT/SABR/SRS are the future of radiation oncology. Not only is technology pushing us in this direction but reimbursement as well. Once capitation comes, and have no doubt it is coming, 1.8 Gy per fraction will die a quick death for prostate cancer.

Completely agree; patients are nudging us in this direction as well. Many physicians seem to underestimate patient convenience as a factor.

 

[medgator]

I just don't see it happening as quickly as in breast.... you're still never going to treat a Gleason 9 with 5 fractions or even 28 fractions, or someone with an 80cc gland and an AUA of 16.

 

[RadOncDoc21]

wait a second....adoption of breast hypofx happened quickly???
could have fooled me.
We have 10-15 year data and people still using any reason they can find to treat in 30-35 fractions! (patient too young. patient had chemo. patient's anatomy too big. high grade disease. patient has DCIS, not invasive disease. need to get my kid's 529 account funded).

Yeah, what good is hypofx if you're adding a 2 week boost to everyone? With that said, I do see it being done more... just not in FL!

 

[medgator]

wait a second....adoption of breast hypofx happened quickly???
could have fooled me.
We have 10-15 year data and people still using any reason they can find to treat in 30-35 fractions! (patient too young. patient had chemo. patient's anatomy too big. high grade disease. patient has DCIS, not invasive disease. need to get my kid's 529 account funded).

I think people are doing hypo fx more in breast than they are in prostate, obviously no data to really prove that, just a hunch. Plus intuitively people are probably more worried about bladder/rectal toxicity than breast toxicity when trying to make that jump.

That being said, it's up to astro to update their breast hypofx guidelines for chest size, age, chemo etc if they don't want people using those reasons to not do it. But astro is slower than a turtle...look how long it took them to update the apbi breast guidelines, which they did recently

 

[BobbyHeenan]

I agree that I think the Stanford regimen (the one I believe being used in the upcoming RTOG trial) is going to be the "sweet spot" for dosing.

I am hoping to open the NRG/RTOG trail at my clinic (28 vs. 5 fx). Right now I do offer 28 fractions to probably the majority of my prostate patients, excluding the large prostates and high AUA symptom score patients. Off study I've been a little reluctant to offer prostate SBRT, but I'm going to enroll on the RTOG trial when it becomes available to me. I'm probably just being overly conservative though and wouldn't blame anyone doing it off protocol now, as it is in NCCN guidelines as an "alternative" to more conventional fractionation.

 

[OTN]

I see very, very few prostate patients (maybe 5% or less of my practice), due to the large urology group in town having a linac. I do offer SBRT to patients if I think it's appropriate, but it's not going to matter to me much either way when it comes to getting patients. I don't offer 28 fraction hypofractionation, as if the patient is interested in going that route, IMO it makes sense just to do SBRT.

I treat the vast, vast majority of breast cancer patients with hypofractionation- probably 90-95%: essentially all the ones for whom we can get hot spots below 107%. Seems dramatically unethical to me to do otherwise, as patient-reported cosmetic outcomes were better in the hypofractionated arm. I do add a boost, however.