Dr. Nadim Nasr
Appearances
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
No, and honestly, we do almost a mirror image of what you guys do. We do three days of Cipro leading up to the fiducials and the spacer at the same time. Very similar in terms of setup. They do an enema the morning of before coming in, and we go from there for the actual procedure. And do you do the fiducials first and then the gel? I do the fiducials first.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
I did make the mistake once of trying to put the spacer first, and what I didn't realize is that the ultrasound image It's completely distorted once that spacer goes in and you really cannot see where you're going with the fiducials. So I always start out with the fiducials first and then go with the spacer second.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
I mean, I tell them that obviously if they're still awake during the procedure, if it's not a sedation procedure, that they're going to have a little discomfort while I'm putting in, you know, numbing them up, putting the markers in, putting the spacer in. And I talk them through it step by step as I'm doing it. And most men honestly tolerate it just fine.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
I warn them that once that spacer goes in, they will have feeling of rectal fullness, feeling like they have to have a bowel movement. I remind them that they just had an enema a little while ago and there's really nothing to come out. and so that tends to relax them.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
Once we finish the procedure, we tend to get their legs down, tend to get their legs to bend their knees up a bit, and I think that helps them a little bit with that sensation, and it generally goes away within a few minutes. I do warn them that they may see a little bit of blood in the urine or stool for a day or so after treatment.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
Obviously, most of these gentlemen have had a prostate biopsy not too long before, and so they're pretty familiar with that. And that's really about it for the side effects. I mean, I prepped them and most of our talk obviously is on the side effects of the radiation, not necessarily this.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
Because we're moving to so much SBRT now, all of those patients, and we have a CyberKnife as well. That's our main SBRT unit. All of those patients are planned with both CT and MRI imaging. When we do our treatment planning, we're doing a CT simulation in our department And then they're going straight to radiology for an MRI right away in the same day.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
And then we fuse those images based on the fiducial markers. And so you get a nice registration of the two images. And you can see that hydrogel very nicely on those MRIs. And where will there be a benefit using the spacer view? There was a short time period where we were doing a lot of spacer and we were still doing a lot of IMRT that was purely CT based for planning.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
And I did use it for a brief amount of time there. But again, now that most of what we're doing is based on both CT and MRI imaging, I don't really use it anymore.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
So we're a little bit different. I mean, we're a hospital-based group in the sense that we contract out to the hospital to do all their radiation professional services, but the technical fees still go to the hospital, including a lot of the technical fees for the equipment, the medications, the gels, and things like that. So that's a loop through the hospital process.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
But we're, of course, conscious of that. Where our challenges come in are some of the insurers in the area will not cover a spacer, or at least not initially. And so in those cases, what we've started doing is placing the fiducial markers, planning the patient, and then if it looks like there's absolutely a need for spacing because of compromise on either coverage or
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
or rectal dose, then we'll go ahead and make a request to put in the spacer. So those are the challenges that we face on our end.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
You know, with SBRT, generally from the time of fiducial and spacer placement till treatment is about at most three to four weeks in our practice. And my experience is the spacers really held its shape and integrity very well. I've not had any problems with that. And even back when we were doing longer courses of IMRT, I didn't even see any issues even up to about two months out.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
at least with spacer. So my experience has really been that it does maintain its integrity and shape.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
Large prostates, it absolutely matters. But again, it matters on the particular anatomy. Is it a large prostate with some separation between the prostate and the rectum, or is it one of those prostates where the rectum is draped across the backside and on top of the prostate? Obviously, if somebody has a large prostate or they have higher risk disease, we are putting them on ADT.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
And again, if they're having a lot of urinary symptoms or they have a large prostate, I will put them on ADT for a couple months before treating them versus if they don't really have any of that, we'll go ahead and start ADT and then within a few weeks treat them.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
I have not had an issue with re-spacing. I have had the issue of having to re-scan and re-simulate for planning just to confer. And I think the longest we had was about a three-month gap, and it still looked very good. I mean, I think it was a little bit small. I compared it back to what we had seen before.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
I think the spacing was a little bit less, but it wasn't so much as I would have considered re-spacing. I think they were perfectly fine proceeding with treatment. Luckily, though, they had good anatomy as well. And that was three months after original placing? Three months after placement, whereas usually we'll scan usually about two weeks after spacing.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
This is a big reason why we're the ones that are putting a lot of these spacers and fiducials in and not the urologists that send them to us. A lot of the urology groups that we get patients from have standing stentors. They're their own practices, and I think they're very happy not dealing with it, honestly.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
I mean, that's exactly what I tell them is, you know, the gel will dissolve. I think they will end up with a lot less perirectal scarring in that area. And, you know, I've gotten some feedback from the gastroenterologists that we work with, really just for my own curiosity as to what they're seeing on colonoscopies on some of these patients, you know, routine colonoscopies. And
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
They do tell me that they're seeing a lot less telangiectasias in that anterior rectal wall. They're seeing a lot less post-radiation changes. I mean, they're still there. I don't think it's going to go away. We're still getting a decent dose of that anterior rectal wall, but it's certainly not something that I think has long-term consequences.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
When we first started doing the spacer back in, I think it was 2016, 2017, when it first came out, most of the data was on external beam and IMRT. And there was actually very little data on SBRT. So we had some residents rotating through that put together some of our data for us. And essentially what we did was we did a comparison of rectal dosimetry for CyberKnife between patients that...
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
had spacer versus ones who did not have spacer and we tried to match patients up based on prostate size which was the one factor that we we thought would equal things out and essentially what we saw was anywhere between a 50 to 70 percent decrease in dose to the interior rectal wall and specifically a lot of the higher dose points, not just sort of the average lower dose, but the higher doses.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
So that's what convinced me to start using it really routinely.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
Honestly, on the spacer, I feel like once it's in that perirectal space, it's going to go sometimes where it wants to go. And as long as I've got some separation, that's really all I need. I'm much more particular about the fiducial or marker placement, especially for CyberKnife SBRT, since the imaging for that is really based on 45 degree plane films of the pelvis.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
So you really want to have those four markers separated in two separate planes, actually really three separate planes. So we do four fiducials now for everyone, just because we end up with the two markers in each needle that are tethered together. So you get a lot less migration of the markers and you can really separate them in terms of their planes.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
But I'm much more particular about the fiducial placement than the actual spacer placement. With the spacer, I'm just happy if I get any separation.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
So for the fiducial markers, you really want to put them in in separate planes so that no marker is blocking another one. If you can imagine taking 45 degree x-rays to the pelvis. And so you want one set that's a little bit deeper than the other if you're looking from a transperineal standpoint. And you want one set that's a little bit more anterior, another one that's a little bit more posterior.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
And as long as you do that, you are going to see four separate markers. Now, we only need three to track. And so the other one is thought of as our spare. So in case you have any shadowing of one marker versus the other, or one marker is really just out of bounds because of distance, you can just turn it off and track based on the other three.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
And I leave any, anything you want to add? Yeah, no, I mean, I think we are lucky in the sense that we do have the capability of getting anesthesia down for some light sedation. And I always lead it off with my patients and asking them how they had their biopsy done and how they specifically did with the biopsy.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
Guys who are telling me they were awake for the biopsy and it was fine or slightly uncomfortable, but fine. I tell them that they're probably going to do very well with this and they don't necessarily need anesthesia, which of course comes with spending the entire day at the hospital, of course. But from time to time, I have guys who say that the biopsy was very uncomfortable and that
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
Those are the guys that I try to say, well, maybe we should have you sleep for this procedure. It certainly makes it a lot more efficient on my end to get these things in.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
It's the American Society of Radiation Oncologists, but it's termed ASTRO. It was a lot more complicated than they simplified it.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
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BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
So I joined the practice here in 2010, so I've been here for 14 years now. We started out as a small practice of two radiation oncologists. We've now, over the last 14 years, expanded to two centers. They're both hospital-based, community hospital-based, and there's four of us in the group.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
I am the one that does the vast majority of the prostate cancers in the group, but I do treat really everything else. We have the full gamut of options for treatment, including external beam, brachytherapy, and SBRT. A significant portion of my training at Georgetown was in SBRT, and so I've got a lot of experience in treating SBRT, especially for prostate cancer.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
I think there is. And the main reason is that if you look at the changes in the NCCN guidelines, especially over the last four or five years, what you're seeing is a lot more inclusion of SBRT as opposed to IMRT in the treatment of prostate cancer. And with SBRT, you are using such higher doses per treatment that it's really important to try to spare that anterior rectal wall.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
And now with the use of PSMA PET scans to further narrow down which patients are good candidates for prostate-directed therapy, we're really doing more and more of that. And I think that there is really a large need for perirectal spacing in the majority, but not all patients.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
Well, I want to agree with Eric. I think that we've mostly moved away from standard fractionation for prostate cancer. If you look at radiobiologic studies, what they actually show is that most prostate cancers respond a lot better to higher doses per treatment. And so I think we're going to see a significant move towards hyperfractionation in almost, you know, most of these cancers.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
And again, in my own practice, I can't remember the last time I treated a prostate in nine weeks. Most of my prostates, even the IMRT, are done in the five and a half to six week courses of treatment. And again, in those cases, having a spacer in place really does cut down that docety into your rectal wall.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
The only patients that I do hesitate in placing them, and I place my own spacers and fiducials. It's not our urologists that do them. The only patients that I hesitate in are the patients where we suspect some extension outside the prostate on the MRIs that they had before the biopsies. Those are the ones that I do hesitate in putting in spacers.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
So there is some data in the radiation oncology literature that suggests that placing a spacer when there is extraprostatic extension could potentially push some of those malignant cells away from the prostate and away from the high-dose region, especially if you're using very conformal techniques like SBRT.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
Now, where that is going to end up, and we don't really know, we're going to have to see what the future of the data holds, but Those are the cases where I might hesitate a bit in putting in spacer initially and might consider putting it down the road if my initial dosimetry shows that I'm compromising coverage to spare the rectum.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
My experience parallels Eric's in terms of seven or eight years ago, we started using Spacer and You know, we're really doing, I mean, I probably end up doing somewhere between 50 to 100 cases a year. I did try the Baragel. I felt that the entire process of switching the tubes and the needles was a little clunky.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
And I never really liked the end result of how the gel separated versus doing the hydrodissection and knowing that, well, you've got a nice space and you can go. The only time that I feel, at least in my experience, that there may have been a slight advantage
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
is in patients who we are retreating with radiation, where there's a lot of scar tissue in that perirectal space, and it will simply just not hydrodissect with the saline. I have used Baragel in those cases where I knew where the positive nodule was in the prostate to try to get some separation behind it.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
But that's really, I mean, I would say, you know, less than three cases that I've done in that. The vast majority that we're doing is Spacor.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
There's no prostate, so...
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
So we have a procedure room in the office and we do it all in the department itself. I would say it's about 50-50 whether we do it with local numbing versus getting anesthesia involved for some sedation for the procedure. I really leave it up to the patients. I mean, from my end, it's really the same procedure. I agree.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
I think the vast majority of patients tolerate it very well with really just minimal discomfort. Some men do have about 10 to 15 minutes of some rectal pressure. feeling like they have to have a bowel movement, which dissipates in most of them. And we've had our share of a couple of guys who had a little vagal response and we had to wake them up a little bit.
BackTable Urology
Ep. 191 Optimizing Radiation Therapy: Role of Perirectal Spacers with Dr. Eric Chenven and Dr. Nadim Nasr
But, you know, the guys who end up having some light sedation with anesthesia down in our department, by the time they wake up, they really have no symptoms whatsoever from it.