Thanks for posting this. If people are considering a spacer see if your Dr offers Barrigel. That is what I had and it seems more "user-friendly" as it does not have a limited working time like SpaceOAR, and it is said to be reversible. My RO said he has yet to use the reversible function.
My RO prefers to use the version of SpaceOAR with contrast agent included, so that he can see it clearly with a CT scan. That helps him to better line up the X-ray beam with the prostate.
Not "clearly." These are physician-reported, not patient-reported, which would be more accurate. For physician-reported toxicity, they only report what the patient tells them about. Because of this, Grade 1 is often not reported, and in most research papers, researchers report Grade 2+. It is also difficult to see why GU toxicity should be lower, since the spacer only effects the distance between the rectum and the prostate - it doesn't change the bladder spacing whatsoever. It also can't be used when there is any suspicion of EPE because of the danger of protecting the cancer from radiation.
As you can see, if you only look at Grade 2+, there is little advantage to the spacer and the numbers are so small that it is an expensive treatment for an almost non-existant problem. Careful contouring by the RO and more precise linacs can replace it entirely.
Considering that there are risks of rectal ulcers, the added prostate compression changes the tissue density, and the danger of protecting the cancer, RO's should offer it only when there is clear anatomic risk.
Thanks for your remarks. I was curious why Marianos (2015) and Hamstra (2017) didn't report Grade 1 toxicity. Your explanation makes sense. However, both Chao (2020) and Miller (2020) did report Grade 1 toxicities, which were significantly worse for the "no spacer" group and better for the "spacer" group. Regarding grade 2 toxicities, the rates are relatively low, but both Miller (2020), and Marianos (2015) and Hamstra (2017), reported significantly worse toxicities for the "no spacer" group and less toxicities for the "spacer" group.
My article uses patient-reported outcomes, which are less problematic. If you read it, you will see that "significantly" worse toxicities is barely any at all.
Thanks. My problem is that I don't have the original full papers to read. Just someone else's summary from the NICE paper. I did read your article, at least twice.
Thank you! I have talked to Dr. Kishan at UCLA about doing MRI-Guided SBRT. He says that the MRIdian machine that they have will be back up and running in a few weeks (after a new company bought ViewRay, which went bankrupt recently). Where did you husband get his treatment done?
Could you explain the differences between physician-reported outcomes and patient-reported outcomes? I don't understand the differences. Seems like the patient would fill out an IPSS or EPIC questionnaire and give it to the doctor, who then adds it to his/her database and reports it later. Or the patient complains about 1 or 2 symptoms to the doctor, who adds that to the database. I don't see any distinction...
When a patient fills out a validated guided questionnaire like IPSS or EPIC, it is called a "patient-reported outcome (PRO)." OTOH, physician-reported toxicity depends on the patient to voluntarily tell the doctor any issues.
The issue is reproducibility. EPIC is validated, meaning that one large random group gives the same answers as another large random group. But like all statistical measurements, there is a finite error when smaller subgroups are asked. For that reason, we look at "minimal clinically important difference (MCID)" The MCID varies between EPIC-26 domains. A mean change of 4–6 points is considered clinically significant for the bowel and vitality/hormonal domains, a change of 10–12 points for the sexual domain, 6–9 points for urinary incontinence and 5–7 points for the urinary irritation/obstruction domain .
I appreciate now why PROs are more "comprehensive" and "reproducible" than doctor-reported events that the patient may, or may not, complain about. Hence, the lack of Grade 1 data in patient reports and/or complaints to the doctor. Thanks for setting me straight.
Physician-reported toxicities are not as reproducible as PROs. They depend on the patient actually being motivated enough to complain to his doctor. Toxicities are categorised as 0-5 by the CTCAE guidelines.
I think of the categories as follows:
0=nothing to report
1=expected, minor side effects
2=annoying side effects
3=serious side effects, requiring intervention
4=life-threatening side effects
5= death
For example, my RO told me to expect some blood on my toilet paper after SBRT. For that reason, I did not bother mentioning it to him when that occurred. It would have been category 1, but was recorded as category 0. You can see why 0 and 1 are usually lumped together, and only 2+ is usually reported.
It is a meta-analysis of 7 studies with a total of 1011 patients. Their two primary conclusions are:
"The hydrogel spacer group received 66% less v70 rectal irradiation compared with controls"
"Compared with no treatment with a perirectal spacer during RT for prostate cancer, hydrogel spacer placement was associated with a 77% lower risk for late grade 2 or higher rectal toxic effects and higher bowel-related QoL scores during late follow-up that exceeded the threshold for a minimal clinically important change. "
The other reported toxicities were pretty much the same between the two groups (not statistically different).
Here is a screenshot of FIG. 2, which summarizes results from 4 different studies.
I don't know if these are patient-reported or doctor-reported symptoms.
Here's a Figure from Chao (2020) showing how a rectal spacer reduces the planned radiation dose to the rectum by a large amount. The spacing distance is about 1/2 inch.
I have seen all these, but remain unconvinced. It makes small differences in a rare side effect. I think Boston Scientific has put a lot of marketing effort into SpaceOAR. Patients, thinking it makes a meaningful (note: "meaningful" is very different from "statistical signicance") difference, ask their ROs for it. It is easier for ROs to accede to patient demands than to argue it, especially because Medicare covers it. The cost to Medicare is substantial, but is invisible to the patient (US healthcare costs are by far the highest in the world).
From the RO's POV, it makes his job easier. Contouring is a time-consuming, mind-deadening process. SpaceOAR makes it easier because he doesn't have to contour as carefully.
In the UK, it is not routinely approved because they find the evidence unconvincing.
I think the value is in helping patients feel more confident, even if the actual benefit is small (and there is no evidence of EPE). What is that worth?
"From the RO's POV, it makes his job easier. Contouring is a time-consuming, mind-deadening process. SpaceOAR makes it easier because he doesn't have to contour as carefully." - my radiation oncologist also said that SpaceOAR (and gold markers) can allow the techs running the machine to put their minds to sleep and not pay as close attention to the treatment. He recommended against both for me and I took his recommendation. It's not just the RO who looks to make their job easier with SpaceOAR, it's the actual people doing the treatments - problem is - that equals a loss of accuracy and not as good a result.
Glad I had the RO I did. He was in the control room during all 5 of my SBRT treatments. My fiducials allowed the LINAC three axis from which to determine whether to hold the beam intra -fraction , and I would rather have the addition 1.7cm of space between my prostate and rectum than not.
I just finished HD Brachy at UCLA 2 weeks ago; am waiting 2 more weeks to report here but for this subject, why argue against something that may/probably result in less rectal toxicity. I’m a physician, I’m sure as hell not going to say “ don’t use the space oar, it doesn’t help.” I’m a big advocate of might help, won’t hurt. Anyway, Dr Chang used a balloon spacer instead, said you get better spacing. So far, so good, will write more later.
I think the problem is that there is potential morbidity associated with its use. I chose to forego for that reason. Small but significant risk. Small (but probably significant) benefit.
See this reference:
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.
Aminsharifi A, Kotamarti S, Silver D, Schulman
J Endourol. 2019;33(10):868. Epub 2019 Sep 27.
The manufacturer website reported risks including pain, needle penetration, and/or gel injection into a nearby organ or blood vessel, local inflammation, infection, urinary retention, and local rectal injury or symptoms. There were 22 unique reports discussing 25 patient cases in the MAUDE database from January 2015 to March 2019, with an increasing number of reports each year up through 2018. Unique major complications including acute pulmonary embolism, severe anaphylaxis, prostatic abscess and sepsis, purulent perineal drainage, rectal wall erosion, and rectourethral fistula were reported. Conclusion: Despite well-documented clinical benefits of the SpaceOAR System, there are a number of severe and debilitating complications recently reported in proximity to gel injection. This highlights the need for further study of device complications in light of its increasing clinical use.
Thank you for the reference. I had run across this earlier today. What is missing from this report is the total number of people that have had spacers during the period of 4 years. Is it 100, 1000, 10000, 100000 ? They only list 25 bad cases over 4 years. But, what proportion is this? If there are 200,000 new cases of prostate cancer each year, and let's say that 10% of them get radiation treatment, and the 50% of that group get spacers, then that is 10,000 users of spacers per year. SO, 25 bad cases, reported over 4 years, makes the rate of incidence about 25/40000 = 0.06%...very rare. Again, people should chose doctors that have performed 100's, if not 1000's of spacer installations. It would be interesting to compare those # of bad cases between PEG spacers and hyulranic acid spacers...which is better or worse?
I think the risks with spacers are down to inexperienced doctors. Hence in the UK, I had to travel to Windsor to see a doctor who does several spacer insertions a day. It took all of 10 mins and I could see the Barrigel being inserted in just the right place on the ultrasound screen. The prostate ended up about 5 times further from the colon than it was previously.
I agree. Thanks for sharing your experience. The RO I;m seeing has done thousands of spacer insertions. So, I feel comfortable with going that route. It's seems to be a no-brainer. I heard that Barrigel has a contrast agent now, which makes it show up on CT and MRI much better.
I specifically asked my RO how many untoward side effects he has seen from spacers that he had placed. " I have been placing many hundreds of spacers over many years and I have yet to see an adverse side effect. I am not telling you that it is impossible that you will have one, but I am very confident that you will not". He changed from SpaceOAR to Barrigel a year ago. I have had zero side effects from the Barrigel and my MRI showed a 1.7 cm (.67 ") separation between my prostate and rectum. When we are talking margins of 3-5mm with SBRT and the Barrigel gave me a space of 17mm........you do the math........
"36 (41%) cases had rectal wall infiltration on the post-SpaceOAR insertion MRI. 20 (23%) were grade 1, 9 (10%) grade 2 and 7 (8%) were grade 3. Three patients had significant rectal complications, 2 patients had a grade 2 rectal ulcer, and 1 patient developed a rectourethral fistula. All 3 cases had significant grade 3 RWI on MRI, suggesting that grade 3 RWI is a significant risk factor for rectal complications post SpaceOAR insertion. GI symptoms are not a good predictor of RWI, with only 2 of the 7 cases of grade 3 RWI having GI symptoms. For the 2 patients with rectal ulcers- 1 patient had their radiotherapy delayed by 3 months and the other patient proceeded to radical prostatectomy. 1 patient had significant infiltration of SpaceOAR into the prostate. "
This is a study of ........"(a) total (of) 141 patients were identified of which 87 had post-insertion MRIs performed"......."from 1 January 2017 to 30 June 2021".I put little credence in such a small sample from only two institutions. Operator error comes to mind.
With all respect to you and for myself choosing not to do it, the question still remains for everyone reading this and making the same decision. It just appears there’s not enough data to know the true benefit to risk at this time.
Well I was fried with 39 salvage sessions (5 days a week for 8 weeks - minus 1 day for those who do the math). No spacer..........and I ended up with a crimp in my left urinary tract that required in and out stents for several years (no issue with stents going up my WILLIAM - note: upper case). Doctor(s) could never conclude if it was from frying or from previous kidney stones (had a few of those from time to time). So I leave you with a decision, "6 of 1 or half a dozen of the other". Pca really really sucks......
Thanks, John, for sharing your experience. It sounds awful.
It sounds like you're talking about your left ureter, which is above the bladder and far outside of the intense radiation zone. I doubt that the small amount of stray radiation would have caused this problem, and a spacer would not likely have helped at all (its purpose is to move and protect the rectum.)
Only your RO would know if a spacer would have helped...
My RO told me he sometimes chooses not to use the spaceOar stuff. The reason he gave is that if he suspects PCa cells on the outside of the capsule, he feels the spaceOar could move them out of the shooting range. ?
It's mostly a theoretical concern, especially if there is clear signs of extra capsular extension (ECE). There is only one anecdotal case of a rectal tumor that may have been caused by a spacer in a person with ECE who had RT.
Dr. Kishan and Tall_Allen says it's a bad idea (with ECE). But, my RO says the benefits of the spacer outweigh the risks (with ECE). There are no papers that talk about this situation, despite the estimated large number of spacers (~10,000) that are used every year. If it was a significant problem, someone would have written about it.
There still is radiation to the rectal wall, even with the use of a spacer. It's much less than the prostate, however. So, the displaced wall is still irradiated, although at a lower dose. As a result, some of those PCa cells that are trapped behind the spacer will be killed by the very high-energy X-rays (4-6 MeV), just not all of them.
If you do use the spacer, you should probably monitor your PSA more frequently after RT to watch for any possible growth outside of the prostate (assuming you have ECE).
What kind of RT are you planning on getting? SBRT? Where?
I was treated for PCa in 2020. The SpaceOAR procedure was just being offered in the UK, after reading about the possible benefits I decided to go ahead with the procedure prior to treatment for PCa.
My treatment for PCa consisted of 7 months of ADT and 20 sessions of radiotherapy.
4 years later, I have no issues with my bowel or bladder. To be fair I may have had no issues anyway regardless if I had the SpaceOAR procedure or not, but anything that may prevent future side effects of PCa treatment must be worth pursuing in my opinion.
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