To SpaceOAR or not to SpaceOAR. That... - Prostate Cancer N...

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To SpaceOAR or not to SpaceOAR. That is the question.


I have decided now on SBRT for my PCa.

One open question remains: Mr OAR.

23cc prostate and good margin to rectum with SBRT approach

Dr thought not much benefit for me given my geometries, but still provides maximum possible protection.

The flip side - Dr mentioned 1% of his customers with some awful complications. 1% seems not too bad odds though to get maximum protection.

Love to hear the community experience and thoughts.

Here is a study i found on side effects:

"Results: 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."

Thanks for any help, my best to you.

22 Replies

But only about 1% benefit from it. It is a cure in search of a disease.

I am VERY down on it since my friend had it. I pushed the cancer against the rectum protecting the cancer from radiation - caused him lots of pain and problems until his dying day.

45RPM in reply to Tall_Allen

Ouch, hate to hear that.

Ya that was the feeling i got in my conversation with Dr Meier, just not seemingly worth it in my specific case given the awful downside where I already had favorable margin.

Tall_Allen in reply to 45RPM

Robert Meier is among the best. Very few have more experience than him.

45RPM in reply to Tall_Allen

We had a really good conversation. I was well prepared and we cut right to the chase. I led the conversation. He called me the most well informed patient he has ever met. I hit him with a list of questions based on your SBRT question sheet and the info and experience i gained from the soldiers on this site. This was only possible because of this community and your web site. I am so grateful to the men on this site. The people who so graciously and courageously help each other and helped me sooo much. I shed a tear now as I write this. The supportive partners, daughters, sons, brothers. And you Mr Tall Allen. Especially you sir. You got me here. Words cannot express my gratitude to you. Thank you so much. I feel at peace now about my decision, this awful decision, but now I can say did my best, now go get it done and not look back. 🙏🙏🙏🙏🙏

Tall_Allen in reply to 45RPM

Thanks for those kind words. I learned from my mentor, Chris King (Dr Meier knows him well). There is not much about the disease that we can control, but we can do a lot to minimize treatment regret. You may be interested in this patient questionnaire that he used at UCLA:

Hidden in reply to 45RPM


45RPM in reply to 45RPM

T_A I wonder if there is any data on secondary cancers for SBRT vs the other external radiation approaches - i wonder if the tighter margin would help to keep bladder cancer rates down to normal for population. and same for rectum, any chance with SPaceOAR and SBRT we see less secondary/late cancers?

I had SpaceOar last year for HDR-BT and IMRT. I've not had any radiation-type SE's in the last year since the procedure, so thus far, I would deem it successful. There's some studies out there on it-- google those and read up on it. It gives about 14mm separation between the prostate and anterior rectum wall, so it made sense that it would provide some protection to the rectal wall during IMRT. However, it is relatively difficult to place, as the RO needs to inject the gel in a way that makes a symmetrical space into a surgically prepared cavity, so try to make sure your RO has done it at least a few dozen times if you decide to do it. I saw an MRI of mine, and it was perfectly done by Dr Chang at UCLA. I could feel it the first few months if I sat on it a certain way, like on a bike, but it seems to have dissolved now, don't even know I had it. I would recommend it, but you have a lower risk profile than I did, so it may not yield the same benefit.

45RPM in reply to timotur

Thank you timo, appreciate this perspective, Mr OAR totally makes sense hypothetically. Every fricken decision down the decision tree is froght with a little risk of something horrible. Such a bitch this thing. I am looking forward to the day very soon where my toughest decision is which wine should I have with that steak. Take care.

timotur in reply to 45RPM

Yes, tough decisions 45, I was Stage t3b +LN and needed pelvic coverage, so I thought SpaceOar was worth the risk. For SBRT to the prostate only, maybe not so much. Best to you, and luck with the easier decisions down the road after treatment, like your choices of a good wine!

My RO discounted it outright, he did not specify and I did not ask if the decision was specific to my case but it seemed like he was against it all together.

I raised it with my docs (uro and RO). Both recommended against it based upon clinical experience and the fact that I had had multiple biopsies and they thought it might be difficult to insert/place the gel in the correct spot. Just saying.


PS: Agree that Tall Allen is a great source of information and support.

I had it and had and have had no problems with the placement nor rectal side effects. Therefore my opinion is favorable.

As a scientist and a cell biologist, I can't imagine a geometry that would make this the wrong thing to do. The gel is injected between the prostate and the rectum. This is not a cure as was mentioned above. This is merely to protect you from side effects of radiating your rectum tissues. This gives you an additional 1/2" or so buffer. If only it could be inserted between the prostate and the bladder!

I did my reasearch and opted for the space OAR and still had some bowel urgency and frequency issues during and after treatment. RO was ambivalent on its valuebut supported my decision. I had a pretty bad reaction to the anesthesia used for the placement procedure too. According to the RO there was a void in the OAR that allowed some rectal damage during SBRT treatments. Not a chronic problem but bowel frequency has been with me since treatment.

I don’t understand why you wouldn’t have it, if you can afford it. It creates a Temporary space between the prostate and the rectum, which allows increased dose to the prostate. It has no downside. The story above about “pushing the cancer into the rectum”, if true, sounds like complete incompetence.

I had it done at same time as fiduciary markers, so there is no additional surgery.

This study was done by my doctors.

Significant reduction in late rectal toxicity.

45RPM in reply to Stevecavill

My Dr reports he has had 1% case where it causes major side effects that sounded very nasty. Something like it growing into the rectum wall i thought or not dissolving properly, but i wasn't clear on what happened exactly, but SE sounded horrible.

I think you have to weigh up the pros and cons. A very small chance of side effect from the gel, (which I’ve never heard of) vs the Much higher chance of rectal damage from radiation (which is lifelong).

Maybe get another consult from a different radiation oncologist to confirm.

I've read too many accounts of radiation problems and damage. I was steered toward radiation but opted for full gland HIFU instead. More than 3 1/2 years post surgery and no regrets so far. I had researched space-oar when I was still on the radiation path.

I’m set to have Cyberknife next month at UCSF, just waiting on the gold markers to get installed :/ I asked them if SpaceOAR was used they said no they don’t use it for that particular treatment. Also no ADT which is even better

Just to close out the thread for me - I decided against space Oar. Main reason is it could block radiation to micro-cancer outside my prostate - low risk, maybe, but an important aspect of SBRT for me was to get some spray at the edges of my prostate with the potential to zap micro-cancer just outside the capsule. SBRT contouring and my favourable anatomy should provide the protection i need for late rectal, but this is the trade off, as always, we will find out later how well this decision went.

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