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SpaceOAR - Augmenix, Boston Scientific, and Conflicts of Interest
- Thread starter elementaryschooleconomics
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How did you interpret "severe"?
It says "11% of men experienced at least one bowel complication (defined as receiving a procedure of the large bowel and confirmed diagnosis of radiation toxicity) within two years after radical radiotherapy."
"Receiving a procedure" is a vague term.
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The term "severe" comes directly from the report.
Perhaps the report was actually written by Boston Scientific!
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Rectal/prostate abscess requiring an elective colostomy was by far the worst rt associated complication I've ever seen (in a spaceOAR pt), which happened to require a surgical procedure to address.
I've never heard or seen of said complication prior to that, although theoretically it is something that could be of concern with TRUS fiducial placement, the issue is your keeping the needles in a lot longer and with hydrodissection and subsequent hydrogel placement
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London bridge is falling down you say.Well, if you get your prostate treated in the UK (or perhaps some other 2nd/3rd world country) your risk of "severe gastrointestinal toxicity" is 11% within 2 years of receiving XRT, according to their 2020 report: "Results of the NPCA Prospective Audit in England and Wales for men diagnosed from 1 April 2018 to 31 March 2019 (published January 2021)".
11% seems extremely high.
Are they treating all of their prostate cancers with protons or something?!
Perhaps coincidentally (or not), the rate of "severe gastrointestinal toxicity" increased from 10% (as reported in 2019) to 11% (as currently reported) -- and the use of moderately hypofractionated XRT also increased from 91% (2019) to 96% (2021).
"Hypothesis generating"?
Certainly, there can be no relation!! Blasphemy!!
SneakyBooger should be banned already!!
View attachment 348821
When I first read CHHiP I thought "These toxicity outcomes are horrid."
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A SpaceOAR and proton abstract from 2022 ASCO GU Symposium. Kudos to the investigators for looking into this.
From the abstract:
1. "Rectal spacers improve bowel toxicity in men treated with photons (i.e. IMRT)".
The $830K SpaceOAR study was negative as did not meet primary objective. Also, see below.
2. "the relative benefit of rectal spacers in men treated with protons remains unknown".
Yet many, or perhaps all, proton facilities use SpaceOAR. Why?
I occasionally have patients who will state, "My friend who had protons had a spacer placed". I explain that due to the possibly greater risk of rectal toxicity with protons that the risk of spacer placement may justify the need to use it.
3. "proton therapy may result in high-dose exposure to the anterior rectal wall".
There is more data to support this statement than statement #1 yet the word "may" is chosen.
4. "Four cohorts were compared: Photon with (Ph+RS) or without (Ph-RS) rectal spacer"...
If one believes "rectal spacers improve bowel toxicity in men treated with photons", is it ethical to have a no spacer group in the photon arm?
5. "In men treated with protons, physician-reported acute G1-2 GI toxicity was significantly lower in men with versus without rectal spacer (6.12 vs 30.77%, Pr+RS vs Pr-RS, respectively; p=0.009) and there was a trend towards lower late G1-2 GI toxicity (8.51 vs 26.09%, Pr+RS vs Pr-RS, respectively; p=0.08)."
"No significant differences in patient-reported outcomes were observed with versus without spacer in the proton or photon cohorts."
These findings add to the data showing physician reported toxicities are significantly higher than patient reported toxicities.
It also adds support to the possibility that the risks associated with spacers may be justified by the increased risks of rectal toxicity seen in men treated with protons.
It also contradicts the initial statement that "Rectal spacers improve bowel toxicity in men treated with photons (i.e. IMRT)" given they found no overall benefit. Maybe due to low patient numbers? Maybe.
The authors publish the physician reported toxicity rate for protons. They do not report the toxicity rates for patients treated with photons. Why were those numbers not presented here? Would be interesting to know.
6. Blinding?
Not known.
I wonder whether this study will be published in full. Much to unpack.
Impact of rectal spacer on toxicity reduction in men treated with proton versus photon therapy.
From the abstract:
1. "Rectal spacers improve bowel toxicity in men treated with photons (i.e. IMRT)".
The $830K SpaceOAR study was negative as did not meet primary objective. Also, see below.
2. "the relative benefit of rectal spacers in men treated with protons remains unknown".
Yet many, or perhaps all, proton facilities use SpaceOAR. Why?
I occasionally have patients who will state, "My friend who had protons had a spacer placed". I explain that due to the possibly greater risk of rectal toxicity with protons that the risk of spacer placement may justify the need to use it.
3. "proton therapy may result in high-dose exposure to the anterior rectal wall".
There is more data to support this statement than statement #1 yet the word "may" is chosen.
4. "Four cohorts were compared: Photon with (Ph+RS) or without (Ph-RS) rectal spacer"...
If one believes "rectal spacers improve bowel toxicity in men treated with photons", is it ethical to have a no spacer group in the photon arm?
5. "In men treated with protons, physician-reported acute G1-2 GI toxicity was significantly lower in men with versus without rectal spacer (6.12 vs 30.77%, Pr+RS vs Pr-RS, respectively; p=0.009) and there was a trend towards lower late G1-2 GI toxicity (8.51 vs 26.09%, Pr+RS vs Pr-RS, respectively; p=0.08)."
"No significant differences in patient-reported outcomes were observed with versus without spacer in the proton or photon cohorts."
These findings add to the data showing physician reported toxicities are significantly higher than patient reported toxicities.
It also adds support to the possibility that the risks associated with spacers may be justified by the increased risks of rectal toxicity seen in men treated with protons.
It also contradicts the initial statement that "Rectal spacers improve bowel toxicity in men treated with photons (i.e. IMRT)" given they found no overall benefit. Maybe due to low patient numbers? Maybe.
The authors publish the physician reported toxicity rate for protons. They do not report the toxicity rates for patients treated with photons. Why were those numbers not presented here? Would be interesting to know.
6. Blinding?
Not known.
I wonder whether this study will be published in full. Much to unpack.
D
deleted1111261
I wonder if the original positive spacer trial with photons was just due to ****ty radiation.
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Should have been equally poopy radiation on both arms. *Should.*
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My best bet would be that the “difference”is due to perfidy.
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deleted1111261
Had to Google perfidy.
Right - equally ****ty in both arms, but spacer helps make up for terrible RT?
Right - equally ****ty in both arms, but spacer helps make up for terrible RT?
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Another data point
I have no confidence in the integrity of the investigators.
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This is hilarious.
Thinking about my own OTV visits, here's how I imagine this happens:
Doc: "Any change any bowel habits?"
Patient: "I think so, I think it's sometimes a little softer, sometimes I'll go twice a day instead of once."
Doc: "Is it something that's really bothering you?"
Patient: "Oh no, you guys just always ask me to tell you if I notice anything different, that's all."
Success! The industry crew now has a Grade 1 GI toxicity to record.
Not only is this abstract gifting us with these shenanigans, it also contains my favorite "trend towards" significance with that pesky p value of 0.08.
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Have seen boomers give ≥1 cm posterior margins with conventional IMRT... Figure that would make spaceOAR look amazing
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Does anyone have the protocol so we know what the radiation requirements were?
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Also, has anyone read the letter to the editor in regard to meriados et al? They discuss the statistical analysis and it is interesting what their conclusion is.
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Let's see...
The younger, smaller margin, more detail-oriented rad oncs who you would send your family to are also the ones giving SpaceOAR. The senior, larger CTV-drawing, less detail oriented radoncs (and who never bothered to learn how to place SpaceOAR so these are the cohort without SpaceOAR) don't. Hard to know if one group is more rigorous on the daily setup/working with therapists or is more rigorous on rectal contour/constraints. Different investigators are grading their own toxicities without being particularly rigorous about it. These factors can explain the outcomes without invoking perfidy.
The younger, smaller margin, more detail-oriented rad oncs who you would send your family to are also the ones giving SpaceOAR. The senior, larger CTV-drawing, less detail oriented radoncs (and who never bothered to learn how to place SpaceOAR so these are the cohort without SpaceOAR) don't. Hard to know if one group is more rigorous on the daily setup/working with therapists or is more rigorous on rectal contour/constraints. Different investigators are grading their own toxicities without being particularly rigorous about it. These factors can explain the outcomes without invoking perfidy.
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certainly plausible. Maybe I am bit to cynical.
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I will say this about SpaceOAR with all the certainty of personal experience -
It appears that the greatest benefit of SpaceOAR is when it is used in patients treated by the Boomeradoncs.
Too bad I can't publish that.
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deleted1111261
But they aren’t the ones using it !!
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Data?
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Data?
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This Emory retrospective is slightly worse than the UCLA MRI guided SBRT paper, which was prospective at least. Numbers are very small and unbalanced arms make me very suspect because the small number arm can do anything. p values are basically meaningless here IMO.
It would have been really nice if they reported the actual toxicity data for photons. That gives us some clue about funny business. Did photons have better physician reported toxicity than protons overall? Smells of hiding their own retrospective data because it may not fit a pro-proton narrative.
I commend anyone who writes anything up. But, this is not more meaningful to me than my own clinic experience. SPACEOAR use for me is strictly motivated by a desire to reduce the risk of late rectal bleeding. It is clear to me that there is some increase in early GI toxicity with SPACEOAR because a minority of men report early GI toxicity (as in before treatment starts of within first 2 weeks) that was essentially never reported without it. This number may not be statistically significant by the tools these authors are using over a cohort of 80 patients or so.
I know this is retrospective and they did what they could, but could someone explain the rationale for unbalanced arms in prospective trial design for me?
It would have been really nice if they reported the actual toxicity data for photons. That gives us some clue about funny business. Did photons have better physician reported toxicity than protons overall? Smells of hiding their own retrospective data because it may not fit a pro-proton narrative.
I commend anyone who writes anything up. But, this is not more meaningful to me than my own clinic experience. SPACEOAR use for me is strictly motivated by a desire to reduce the risk of late rectal bleeding. It is clear to me that there is some increase in early GI toxicity with SPACEOAR because a minority of men report early GI toxicity (as in before treatment starts of within first 2 weeks) that was essentially never reported without it. This number may not be statistically significant by the tools these authors are using over a cohort of 80 patients or so.
I know this is retrospective and they did what they could, but could someone explain the rationale for unbalanced arms in prospective trial design for me?
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This is my perspective based on experience with similar large residency programs
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deleted1111261
Are you using it, Boomer ?
N is 1
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Had great gi toxicity outcomes before hand pre gel.
once a gu i work with who had done several before placed it causing a rectal abscess, it definitely gave me pause.
Never saw xrt proctitis require iv abx and a temporary colostomy. How does that get scored gi toxicity wise?
Major Complications and Adverse Events Related to the Injection of the SpaceOAR Hydrogel System Before Radiotherapy for Prostate Cancer: Review of the Manufacturer and User Facility Device Experience Database - PubMed
<span><b><i>Purpose:</i></b> SpaceOAR<sup>®</sup> is a Food and Drug Administration-approved hydrogel injection used to create space between the prostate and rectum during prostate radiotherapy. It has shown to significantly reduce the rectal radiation dose with lower rates of rectal toxicity...
pubmed.ncbi.nlm.nih.gov
Anecdotes are fun. Once you get a collection of them though, they are publishable, as noted above
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deleted1111261
I don’t believe you. Many people are saying your grade 3 was 40%.
Speaking strictly anecdotally here, I'm a SPACEOAR hater too. Our local urologists are terrible at placing it, and their placements often complicate my planning more than help. Have seen multiple rectal wall infiltrations where I've refused to treat d/t fistula risk, so have to deal with months of bitching from patient and urologist about why I'm waiting to treat. If I tried to place myself, I'd lose the business, so not an option. Many of the urologists also lease the equipment so they sometimes wait months to place until they can accumulate a critical volume that makes it worth the daily lease cost. Patients constantly complain about the delays and end up seeking care at the local academic center. Also, many patients complain of an annoying sensation of rectal fullness that I get blamed for from day 1. Obviously a lot of this is logistics stuff, so I'm sure others have had a different experience, but count me in the hater group.Had great gi toxicity outcomes before hand pre gel.
once a gu i work with who had done several before placed it causing a rectal abscess, it definitely gave me pause.
Never saw xrt proctitis require iv abx and a temporary colostomy. How does that get scored gi toxicity wise?
Major Complications and Adverse Events Related to the Injection of the SpaceOAR Hydrogel System Before Radiotherapy for Prostate Cancer: Review of the Manufacturer and User Facility Device Experience Database - PubMed
<span><b><i>Purpose:</i></b> SpaceOAR<sup>®</sup> is a Food and Drug Administration-approved hydrogel injection used to create space between the prostate and rectum during prostate radiotherapy. It has shown to significantly reduce the rectal radiation dose with lower rates of rectal toxicity...
Anecdotes are fun. Once you get a collection of them though, they are publishable, as noted above
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See this all the time but unclear to me when this is clinically meaningful. I'm rarely doing SBRT so I typically ignore. We have adjusted dose schedule based on early GI symptoms in a SPACEOAR patient however.
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Personal and published experience suggests to me there is a subset of patients that suffer fairly morbid complications from it...
My patient was fairly lucky:
Hydrogel Spacer Rectal Wall Infiltration Associated With Severe Rectal Injury and Related Complications After Dose Intensified Prostate Cancer Stereotactic Ablative Radiation Therapy
Radiation therapy (RT) for prostate cancer remains associated with a dose-dependent and dose-limiting risk of rectal toxicity.1 Contemporary dose-escalated RT regimens,2-5 have improved biochemical control at the cost of higher rectal toxicity. Temporary hydrogel spacer placement between the...
www.advancesradonc.org
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Anecdotally, some of the biggest propents are some academic physicists who never see pts, just isodose lines.Personal and published experience suggests to me there is a subset of patients that suffer fairly morbid complications from it...
My patient was fairly lucky:
Hydrogel Spacer Rectal Wall Infiltration Associated With Severe Rectal Injury and Related Complications After Dose Intensified Prostate Cancer Stereotactic Ablative Radiation Therapy
Radiation therapy (RT) for prostate cancer remains associated with a dose-dependent and dose-limiting risk of rectal toxicity.1 Contemporary dose-escalated RT regimens,2-5 have improved biochemical control at the cost of higher rectal toxicity. Temporary hydrogel spacer placement between the...www.advancesradonc.org
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Oh man...it's definitely not limited to just the academic physicists. SpaceOAR, Calypso, literally any device or technique which can "improve" the lines in the computer.
It's sometimes lost in discussions with them that there's a wiggly, squishy human getting the treatment, not the DICOM file in Eclipse.
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Which structure do you mean by "human", I don't have that on my volumes list... Is in an OAR?
TG-263 calls it "external".
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Honestly outside of SBRT or HDR, of which i do neither, it's hard for me to see a use case for spaceOAR.
I follow my patients in conjunction with the local GUs and we just weren't seeing any problems with significant GI toxicity before the $3k+ gel made its way on to the scene, a solution in search of a problem
I do a lot of SBRT and still don't see the use case. Been doing SBRT for 3-4 years without it. Having essentially zero GI toxicity, either in the acute or 3-4 years of follow-up setting.
I strongly disagree that it's the "radoncs you would send your family to" who are using it, and I think it's neophilia and billing which are driving the technology.
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Rad oncs: “SBRT, you are scary!”
Most SBRT regimens: “The late effects BEDs should be roughly equivalent to traditional fractionation but the tumor response could be higher because of low CaP alpha beta.”
I don't do fiducials. Comfortable with CBCT imaging, though I also do a repeat CBCT halfway through treatment to make sure there hasn't been any bladder/rectal filling change.
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deleted1111261
Great idea!
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Certainly there was plenty of prostate sbrt prior to space oar. Not sure abt fiducials. I have also done a few cases without fiducials and space oar. Physics didn’t like it
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Serious suggestion here. I think this kind of study would be helpful but would essentially just say X approach works. It would be really nice if instead it were possible to organize a collaboration between higher volume centers (PP and academics) and compare complications/efficacy from the different approaches.
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I think this is the hard part and I am very skeptical of any analysis of endpoints looking at low grade, self-reported or soft toxicity. I would put some value in very discrete endpoint comparisons, like number of referrals to GI for rectal bleeding or fistulas, although even these are hard to compare and numbers per practitioner are so low that a given series likely not meaningful statistically. Big data may have value here (normalizing diagnosis of radiation proctitis, lower GI fistulas to prostate CA diagnosis per area codes that include or exclude certain types of practices). But even this data may not be that valuable.
Regarding patient reported toxicity, I always think back to a med school anecdote from my ortho rotation. I was in follow-up clinic with a knee and hip attending and two consecutive patients came in. First patient had multiple complaints related to function but also was an avid runner. Second patient had nothing but effusive praise for the doc and team, reported no functional complaints and walked with a cane. The doc confided to me, "I botched that second guy so bad, his leg is 3 inches shorter than the other one. But, he is happy and has no complaints. I'm very happy with my work on the first guy, but he is unhappy. That tells you something about patient satisfaction."
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Amen
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As others have noted, I am very skeptical of physician reported outcomes compared across multiple institutions to make any sort of evaluation about comparative effectiveness or improvements in toxicity. Not saying it's not publishable, but just whether it's worthwhile.
I think there is value in a single institution series (or multi-institution series) saying, look, we did this, here are outcomes. I think it gets murky when you try to say one thing is better or worse than another based on retrospective data without standardized definitions of things...
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I don't disagree with you. I was thinking more along the lines of what communitydoc above was thinking. There too many ways to skin this Kitty (CK, MR (+/- gel), CT based (+/- gel +/- fiducials) etc). The only useful way of comparing effectiveness (which will be good with all) and acute toxictiy is to do it prospectively and that is just not happening. It wouldn't be high value and there are just too many possible combinations.
Besides, what you really want to know is are there any real warning signs to doing SBRT for prostate cancer using CBCT IGRT without fiducials. Meaning, is there any hint that there is a difference in severe complications (the primary concern) or treatment failures. To me, the advantage to multi-institution comparisons is using the same definitions across modalities and centers.
The other caveat that is important to consider...my a priori assumption is that there is NO significant difference in outcomes. I think that multi-institutional comparisons are much better suited to these scenarios than the opposite.
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so OTN maybe you can tell us a little bit about the workflow. so you get called to the cone beam and you are finding that your therapists have set up pretty well to the prostate without much adjustment from you?
ultimately whether it is published or not published, this just comes down to an individual center's ability. the doc and the therapists and physics either are able to line up to prostate or not, for sbrt, with a small enough PTV margin.
ultimately whether it is published or not published, this just comes down to an individual center's ability. the doc and the therapists and physics either are able to line up to prostate or not, for sbrt, with a small enough PTV margin.
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deleted1111261
Exactly. These types of reports help us out in the real world.
"This is what we did. This is how we did it. This is what we saw."
When Crane does this with 67.5/15, even if it is off protocol, it gives me an additional tool in the tool box. Same with if @OTN has found a good set up for 5fx SBRT prostate. I'm not trying to give him homework - just saying that when we talk about "practical radiation oncology" this is what we mean.
