Rectal Spacer Placement: Who Is The Ideal Patient?

[Dr. Juan Javier-Desloges]:
Yes. We've talked a lot about the basic setup, and I think that the audience probably has a good idea in mind of how they could do it in their office. How do you determine who is the best candidate for space, and do you do it in everybody? Does it matter to you if they're getting IMRT or SPRT or proton therapy or something else? Does the anatomy or the size or the location of the tumor matter to you?

[Dr. Neil Taunk]:
Yes, Juan, that's really great. Before going into say those indications and modalities, one aspect of the periprocedural setup I think is very important is who's helping you and what assistance you may have in your procedure. You can do this by yourself, meaning that you can set up the kit by yourself, your table by yourself, but it's really helpful if you have a very consistent nurse or a very consistent medical assistant that knows how to do at least a portion of the setup for you. Help you get your table laid out how you like, get your patient positioned how you like, as well as assembling the kit.

There are some times required to assemble the kit and having a really proficient assistant being able to assemble that kit for you and giving them the confidence to do that by training them up correctly can just really make for a very successful, very efficient procedure. In our practice, most of our doctors don't assemble our own kits anymore. Our team will and then we'll hand it to us when ready.

To your original question regarding who do we recommend spacing for, some of it is philosophical, but some of it I think is data-driven. If you think about it in the broadest sense, you could recommend rectal spacing for any patient that's receiving definitive prostate radiotherapy, whether that's IMRT, SBRT, protons, combined external beam and brachytherapy, or even radio recurrent disease. That could be for really any size of gland. This goes a little bit beyond the IFU or the instructions for use and a little bit beyond the data from the pivotal trial. Philosophically, you could potentially recommend this to every patient. Where I think it helps to be more nuanced is that there's probably going to be populations that would benefit from it more or you're more likely to expect to benefit from it.

For example, in our practice, we recommend rectal spacing for everyone receiving proton radiotherapy in lieu of say a rectal balloon because we know that high dose region really can only be pushed back by a spacer. The rectal balloon push it forward. There's data from University of Washington that would support that. For say SBRT, it may also depend on what your preferred dose is. If you're doing, say, a lower dose like the R2G regimen or a PACE-B style of treatment, those rectal toxicities may be low enough that you don't feel like you want to use a spacer. If you're using higher doses, say 40 or 45 gray, we use 40 gray in five fractions, the acute rectal toxicity rates go up. We feel somewhat strongly about putting in a rectal spacer at those higher doses, which we believe in because it does yield a lower two-year biopsy positivity rate. You could use it on everybody, but I think there's really going to be populations where it matters.

There is some newer data when you use, say, combined external beam and brachytherapy, that rectal spacing may also matter as well. Some data from Memorial Sloan Kettering and a new paper in brachytherapy just a couple of weeks ago. How do you all think about these different scenarios or who best to recommend it to?

[Dr. Juan Javier-Desloges]:
Yes, I think that we think about it a little bit differently. I would say all of our proton therapy patients receive it. I don't know if we've actually looked specifically at the amount of gray, but really anybody that's going to get SVRT, we recommend it to. Then for IRRT, it's hit or miss. I would say that overall, amongst all, I don't know how many patients we do radiation on prosecutors in a year, but let's say it's 100 although it's probably more. I would say about 50 to 60% probably get rectal spacing. That number was I think significantly lower three years ago, just because we didn't have the best access to rectal spacing at our institution. I was really the only one that had voiced an interest in pushing the program forward. We had one radiation oncologist, he did maybe 20 a year in his office, and it was really not available to the patients who wanted it.

I think a lot of providers not being comfortable with the transparent approach, we just didn't offer it here. Then when I was hired here, I said we should really offer this to a larger group of patients, because there's a number of people that I think benefit. Mainly the ones that you had discussed, but also anybody that may think that they may benefit, whether they have inflammatory bowel disease or some other rectal issue that they would necessarily need it for. Our volume since that, in the last three years, has significantly increased since we've added basically another provider that offers it. I've actually tried to train other providers. I don't necessarily need to be the one that does all the space chores, but it's not the most exciting procedure for urologists. I can't really get the sense that they're so enthusiastic about it. Although I do think it makes a difference for the patients, which is why I continue to do it.

In terms of the prostate anatomy itself, I don't think that there's necessarily a contraindication to size. I don't really look at the peri-rectal fat pad on the MRI. I don't always feel that that's necessarily accurate. If you use an endorectal coil for MRI, although most of us don't anymore, that can obviously interfere with the size of the peri-rectal fat pad. If there is frank invasion of the rectal wall, I don't think those patients are a good candidate for rectal spacing. If they get a PSMA pad and there's an enlarged, if there's a concerning mesorectal lymph node, rectal lymph nodes are now believed to be an accessory pathway for prostate cancer based on a couple of publications. I don't think those patients are a good candidate for spacing because it may limit the amount or dampen the effects of the radiation to control their cancer. Then if there's significant ECE and no rectal wall involvement, I'm just a little bit more hesitant.

Sometimes I'll do an office-based ultrasound. I'm thinking about doing it in the operating room. We will do some of them in our operating room. I think because of the reasons you had mentioned, it's really nursing support. It's a lot of work for a nurse if you think about it. If you have one nurse in there, it's just got to set it up and set the patient up. It's a fair amount of work for them. Giving the patients a little bit of modified anesthesia in the OR, a little bit more comfortable for them and a little bit more easier for the setup. Getting back to the extracapsular extension I will sometimes do that ultrasound just to see if it's someone I'm really considering doing for spatial.

[Dr. Juan Javier-Desloges]:
Some of the nuanced things that I've learned about and who doesn't qualify for spacing, with San Diego, we actually have a pretty large cycling-biking population. I've found a number of patients with pelvic fractures that have been unfixed. In a patient that has a known history of a pelvic fracture that may be blocking placement of the gel because the bone is out of place, I think is a nuanced area where I have actually run into an issue twice where it just was really challenging, if not impossible to get the gel in because somebody had a pelvic fracture from a cycling accident. It's not something that we think about, but something that is now on my mind, as well as some sort of rectal surgery before you can't get a probe in I think in my mind are the absolute contraindications to doing it.

Then that you can probably remember this, but when we first started doing this, there were a number of patients that had issues with, placement of the para-rectal gel and getting a para-rectal abscess. If somebody's had a history of a perianal fistula or inflammatory bowel disease, I will be pretty upfront with them about doing an anal exam just to make sure that there's nothing there that is subclinical that they're not aware of due to that infectious risk.

[Dr. Neil Taunk]:
Yes, I think those are excellent points. The aspect about the high number of cyclists in San Diego is very interesting. We have a relatively flat city in Philadelphia, but I don't think we have quite the same activity as there. You brought up the point about some populations may specifically benefit. That also is a little bit of how our program evolved over the last six to seven years at Penn, particularly with your comment about access. In the very beginning, it was one physician, limited slots, and we were prioritizing patients with either inflammatory bowel disease or more commonly that were on anticoagulation for other reasons. AFib is one of them. Patients that may be at particularly high risk for rectal bleeding post prostate radiation. Then with additional access, additional physicians, and then essentially physician champions, as well as patients indicating that they were looking for this service, then we were able to build out the volume. Those are those early indications before those expanded indications.

You had mentioned about prostate anatomy and size. I very much agree with you. The pivotal trial recommended glands should be generally under 80 grams, but there are data to suggest that you can still get clinically meaningful spacing. A paper from Marcio Fagundes at Baptist in Miami suggesting you can still get meaningful changes, even large glands over 80 to 100 centimeters, or even small glands as well.

Also touched on extracapsular extension. This brings up the point that the location of the extracapsular extension really matters. We'll have patients or physicians that won't send a patient for this, even though it might be in general done in our practice. Or a patient who read their own report and said, "Oh, I have ECE and I didn't think I qualified, even though I want this done." It's helpful for us that we review where that ECE is because if a patient has say anterior ECE or far lateral ECE, that's not particularly important to do this procedure successfully. I very much agree with you Juan regarding the aspect of gross posterior extracapsular extension. There is a theoretical risk that you may cut through that disease. Whether that has been demonstrated to be clinically meaningful or not, we have just chosen as a group to not mess with it. There are other physicians that feel that it's okay, that if you were to lift the prostate, that ECE would travel with it as long as it's not tethered to the anterior rectal wall. Again, we've chosen just not to do gross posterior ECE.

The last point is regarding the potential benefit of this. You had mentioned that population with Crohn's or where patients may have certain risk factors that may put them at higher risk for complications. One thing that we always try to remind ourselves when we do our periodic spacer QA meetings where we discuss cases and we review them together, is that this is an additive procedure. Every prostate cancer treatment does have its risks and side effects. Prostate radiation, prostate surgery, focal therapies, everything has its own potential risks. Prostate spacing is supposed to be additive. If you can do it and you feel it might help, that's great. If you can't, or you might put the patient at risk, we have the information that we have that's fairly robust to understand how most patients will do. We can counsel their choices appropriately for them to make the best decision for what care they want to receive.