So, the second talk has been more on the diagnosis and how that plays into resection decisions. Lesion assessment colonoscopy, translating lesion assessment into resection decisions. This is a video I've shown, but I think really highlights this lecture and the goals of it. So, what am I seeing here? It also speaks to the right colon and folds and looking behind folds and using a cap for what we, to reiterate what we just talked about in this particular case, retroflexing. You can see the steps that Doug just described, and you can see it now here in the video. I just did a left turn and a counterclockwise torque, and I'm getting here at this hepatic flexure because there was a slight deformity of the fold that I was drawing my attention. And now you can see here this friability, this slightly, like maybe 13 millimeter lesion. I'm using a cap to get closer and stay stable. And then I was using some available image enhancement with NBI. So, all of these, this information in my lesion assessment from the original like wall deformity to my technique to get there closer to, well, what is this? It's really small, but is it, it looks like it's a depressed lesion. What should I do? All of that's really important in my lesion assessment to know what next. It's so small. Should I just do FTRD? It's so small. Should I just try to lift it and see what happens? It's an ulcer. What is it? So, I use my lesion assessment skills there to basically tell me that that's a deep submucosal invasive cancer that's not endoscopically resectable based on the risk of lymph node involvement up to 25%, even though it's small. If I do FTRD there, I'm not going to get the lymph nodes. So, I would essentially tattoo that at the area and refer the patient to surgery and I would biopsy the area that was not the heaped up edges around it, but I'd biopsy more into the ulcer area to get the cancer for them. Here's another example of a lesion. So, here you can strikingly see the red area and the fronds, but then I think going back to the lecture I gave a moment ago, there's a disruption in the vascularity that you can see that this lesion is much more than that red. It extends out. So, I think that, again, lesion assessment, how would that have changed how I've managed this by now seeing the entirety of the lesion, this may change the assessment because when I take this lesion out, I want to make sure that I get this bulky part at a minimum in one piece because that's likely where the advanced histology is, but I certainly want to make sure that I also lift and remove the surrounding area. So, this was a tubular veal sydenoma with focal high-grade dysplasia in that area that I described that was the 1S component of this 1S2A lateral spreading granular lesion. So, I'm going back to, again, I like these algorithms for me and these maps of mindset technique and tools because in lesion assessment for resection decision, it's really important. We want, when we are assessing it, our goal is we have a complete, safe, and efficient curative removal in a single session when our mindset is also that we can make a diagnosis of what a lesion is. We don't just say it's a lesion, for example, we are saying that's a lesion that may have high-grade dysplasia, that's a sessile serrated lesion, that's a tubular adenoma, but it's in a patient with colitis, and so all of those things we want to be able to assess in real-time histology, and then we want to use high-quality imaging as a standard. It's not advanced endoscopy, it's not sophisticated practices. We can achieve high-quality imaging with what we have available to all of us, and that's literally optimizing our lighting and having a clean mucosa, using a near focus if that's on your scope, but these things are really available to us with standard endoscopy and that high quality can be accessible and achievable for everyone. And the technique part is how we interpret the polyp, that we would apply classification systems to help us interpret it, that we would optimize the staging specimen, so what I mean by that is that when we do do a resection, we want to isolate out the most advanced histology for the pathologist, so whether that's getting a large resection piece and pinning it for them so that they can have good orientation and give us information for the management side, whether that's that biopsy of the lesion I just showed you and getting the specimen and targeting our biopsy to the histology that we were interpreting in real-time to get that biopsy specimen to the pathologist so that they aren't just saying they're seeing adenoma or normal mucosa because we aren't biopsying the correct area. And then the tools, again, we want to have optimal settings of our endoscopes, the processor, and the monodrome cables. We want to use the water jet, the somatic cone, the caps, and the chromoendoscopy when needed, and then using these optical diagnosis classification systems. I showed this in the last, but this is sort of still the backbone of lesion assessment is what is the lesion look like? We need to look for these things so we can delineate the borders first, and we want to optimize the basics, and that goes back to expanding the lumen, washing the mucosa, and you can see otherwise here this tubular adenoma at the cecum would have been easily missed. Here's another area to optimize lesion assessment. It's hard to assess a lesion when you have a whiteout, so the halation is a real thing in endoscopy. We get these whiteouts often depending on where we are in the colon, how much space is around us, what area we're looking at, and the industry is certainly working to decrease this and make it part of the endoscope, but there's still settings on the endoscope that can often help us, and there's an iris setting that really can change your ability to interpret polyps from this whiteout to being where you can see the patterns, and that's on the processor on all the different endoscope manufacturers have an iris setting currently, and that you can adjust that. Many times we end up when we see this whiteout hitting the brightness and taking the brightness all the way down, and then it becomes really dark, so this is just a subtle point to say that setting can really help you with the lesion assessment. We certainly have classification systems out there that we should be using. The NICE classification allows us to differentiate with confidence between hyperplastic and serrated class lesions in the type 1 of the NICE versus the type 2 adenomas, and really, again, we're using those components of color vessels and surface patterns to guide us between the two different types of histology, and I think for making management decisions, of course, it's whether or not to leave a rectosigmoid left colon hyperplastic behind, but on the higher management decisions between the type 2 and the type 3, it's more, is this a lesion that's endoscopically resectable, or is this a lesion that I need to make sure we remove on block because there may be invasive cancer? Those are things that are really important in our assessment that lead to the management decisions. Here's an example of a type 1 hyperplastic. You can see it's the same color. There are absence of vessels, and you see this uniformity of those, of the dots. This is also hyperplastic, and you see that uniformity there, but the difference here is that you see those vessels coursing across, so all of those are classic type 1. We would not resect those based on that information. As opposed to type 2 in the NICE classification, this is classic adenoma. It's more brown relative to the surrounding. You can see the vessels, and those vessels are all variable in shapes and sizes. You can see pentagons and octagons, and you can see the vessels surrounding the different tubes, tubular structures of that. This is a classic adenoma, diminutive lesion that we would resect using cold snare. Then Doug nicely described a really highly specific feature of adenomas beyond the classification system of NICE, which is the valley sign. When you see this divot or valley in a polyp that's really dark under NBI or really red under white light, that is very specific for an adenoma. This is not a depression. You wouldn't call this a 2C lesion under the Paris classification. You're not concerned that there's invasive cancer here in a depressed lesion. This is a valley sign. It's very specific for an adenoma, and that would prompt you to remove this with a cold snare. Here's another example of that. On the other spectrum then, how does lesion assessment here get us to making management decisions? In every scenario, a polyp shown here, there's cancer. You can see that it shows in many different shapes and sizes. These are all T1 cancers. This is very small in the upper left, but it has the morphology endoscopic features of cancer. You can see the middle has the convergence of folds and that depression and the amorphous features there. It continues, and I had shown this large depressed lesion with that thickened fold earlier. All of these, how does it change our management decision? By knowing right here and now that these are not endoscopically resectable, I'm going to tattoo the areas. I'm going to biopsy the area at the highest yield for the cancer and refer to my surgeon, to the surgeon. We're basically looking for features of deep submucosal invasion when we make these decisions. That's a redness, the firm consistency. You would see expansion or fold convergence. You see these deep depressions. These are all signs and features of deep submucosal invasion. This would certainly influence our management decisions. It's important because what becomes problematic when we don't interpret it in real time is it becomes this evasive, confusing picture if we try to remove a polyp, but we don't get all of the polyp perhaps, we didn't get the cancer part, and then that becomes confusing. If it's fragmented, that becomes confusing for the staging part. Interpreting it in real time and then targeting biopsies, tattoos, or resection, depending on the histology, it's all really important that we do those. These again are different features of that. Here's another set of photos of similarly sized lesions, but you can see all of these on the contrary are amenable to endoscopic resection. None of these have endoscopic features of deep submucosal invasion. I'm using lesion assessment skills here. What are those? I'm using the NICE classification. I would use NBI for that. I'm using the morphologic features, and I'm using the classification systems for lateral spreading lesions to help me determine risk of submucosal invasion. Let's go through some of that. There's the Paris classification that allows us to differentiate polypoid and non-polypoid and within non-polypoid flat and depressed. Then there's the lateral spreading lesion that have four subclasses. In those, we have granular homogeneous, which is this upper left. Those are typically the largest, but they're the least risk of submucosal invasion and they're the easiest to remove endoscopically as opposed to the non-granular types have higher risks of submucosal invasion. Those are often more difficult to remove endoscopically because there is either that submucosal invasion, but also there's more submucosal fibrosis. These tend to be trickier to remove. Even though they're small, may change my management decision depending on how I would inject or if I would need to use hybrid ESD, for example, or if I would need to use a snare tip to insert to make sure that I can grasp the mucosa correctly. All of these interpretations in real time are guiding my management decisions. Not using size alone, but using morphologic features, using these classification systems, direct me under different management algorithms along the way. Here's an example of a LST granular type homogeneous large lesion. Again, this has a very low risk of submucosal invasion. This is not going to preclude me from endoscopic resection. I would inject this and perform inject and cut piecemeal EMR. In this particular lesion, you can see this is a lateral spreading non-granular type with the pseudodepression. There's a risk here. You can see that again, that fold is very fixed. This is going to be difficult to remove in one piece, perhaps because this is going to be a non-lifting area, making it very challenging. In this particular case, you can see it didn't lift very well, but I would likely do or did circumferential incision so that I could then get this in one piece with a snare. Here's an example. You can see with lifting, it very much has non-lifting in that area. That's what this is showing. Sometimes when we start to inject it, we get behind the eight ball because it starts to become harder with the injection. We need to be very deliberate, intentional with our injection when we're doing it so we can use it more to our advantage. In that particular case, then I would do a circumferential incision and then the on block resection. Let me go through a few more examples here. Let me move on with this injection here. Here's a lesion. You can see, but I can't really appreciate it in its entirety. I think it's a serrated lesion. Perhaps I'd get closer. We would image it. We would evaluate it further. I'm trying to expand it, but it's not expanding too much. One thing that may be helpful as well in your assessment is when you inject a lesion, that can help expand it and you can get a better sense of its entirety. This is actually a tubular adenoma. We can see here we're injecting it nicely now, but now we get the extent. I have a much better appreciation of the lesion to assess it. I can now choose my snare. I would use a 20 millimeter snare, for example. We can take this out in one piece. I've made this non-polypoid lesion polypoid by using that dynamic injection and making a nice blub. We can now resect that. That just is an example, again, of things we can do for better lesion assessment that can then help determine our management decisions. Here's an example going back to that lateral spreading granular type, just to again show with lesion assessment, making sure that we resect the entirety of our polyps. Using the blue injection helps this nice color hue, giving us feedback on our resection. Here, injecting a little bit more and just continuing this resection, this will be important as we continue the resection process. That's also important in our lesion assessment that we are using perhaps chromoendoscopy or dye with blue to give us feedback in the lesion's completeness of resection. It's important after we would do the entirety of the resection that we look nicely at the at the periphery and the border for any residual. Here's another example how we can interpret the location, the morphology, and the histology here. We're at the cecum. We're looking at with NBI. You can see the tubular structures. This is a nice type two with high confidence. So what would I do at this point? Well, I've assessed the lesion morphology. I know it's in the cecum. I'm going to inject, but knowing in the cecum when you inject, actually, sometimes there's not, it's not as pliable. You don't have as much room, particularly by the appendix. So I'm just mindful of that, but this is a little bit of a distance from the appendix. So we're injecting this up. And I think my next decision in the lesion assessment going in is if we would essentially remove this in one piece, or if you try to have on block resection, or if you can do this, if you need to do this in more than one. And I think, if you need to do this in more than one, and I think, again, being mindful that we're at the cecum, that's just something to consider. We know piecemeal resection has high yields and effectiveness. And so we always want to weigh risk versus the benefit and not being too greedy. So let's see what's going on here. We're using a 20 millimeter snare, taking your time to get around the polyp, and also to get normal around it. And in that case, it slips. So do you continue? No. You can see as you're resecting that you want to regroup, reposition, get closer. And now I wasn't pushing the snare down enough, then the assistant maybe wasn't closing slowly enough at the time. And so now taking that out in one piece there. So I'm showing this to say again more how each step of the way we're making these decisions that help us with the management. And so in this case, knowing where we were, knowing the lesion histology, knowing what snare to use and what injection technique, I think all of those things can play in. And then assessing then, of course, the area after and burning margins. So let's go through. Here's this one here. This is another lateral spreading granular lesion. And then this is a lateral spreading lesion here that we're injecting. Let's see how we can get to the point I wanted to make here, just a moment. Okay, I think the point here is that even though this lesion is a fair size, that piecemeal resection is a completely viable option as there was no concern of like invasive cancer or advanced histology in that. Here is a case where essentially using, this is a lateral spreading non-granular type, right? This is gonna be a little bit harder to resect. It likely won't lift easily. There'll be some fibrosis. So how do we then translate that into resection decisions? I think here then I still would approach this first with my different lesion assessment tools, looking at the patterns to make sure there's no area that has invasion. And then moving forward, I would still inject next. I'm going on the distal side first. I'm assuming on the proximal side first. It lifted nicely there. So we'll keep going. Give me a moment. Let's see what that looked like after. And then here, I think in this particular part, there was no area that specifically looked like there was deep semi-coastal invasion or semi-coastal invasion. So going from the lateral side in, getting access to the plain, then allowed for endoscopic resection. So going again from this lateral side, I think Doug and Amit will go in a lot more with resection, but I'm just trying to tie in how, when we make an assessment early on, that ties into what endoscopic resection technique we may or may not use. So in this case, proceeding with piecemeal EMR worked because there was some lift. We are able to see that there was not any concern for deep semi-coastal invasion, and we'll go through. And you can see here, there are areas that don't capture upfront, but as you keep accessing it with the plain you've cut, eventually this will nicely be cut here. This is the end result after some sequential injecting cut. And I think in the final moment here, this is just an area, again, lesion assessment. So in this particular case, there's this pseudo-nodule, or there's this nodule in the center that's making me concerned. So in this particular case, you would want to cut that in one piece for histologic staging, for example. So in that case, certainly having an on-block resection would be really important. So I think we can end there, Doug, and take home points where we want to characterize lesion morphology and histology in real time, approve these, choose these appropriate strategies, and be intentional with our decision-making. Fabulous, thank you. Thank you, Tanya. So I think that what I'm hearing from your presentation is that we're going to use the tools of assessing the entire surface of the polyp for features that could suggest cancer. And also we want to classify the morphology. And that's going to bring us to a set of lesions that we think is at higher risk of cancer, and another group of lesions that we think is at very low risk of cancer. If the risk of cancer is higher, we have a greater impetus to try to do an on-block resection. If the risk of cancer is very low, piecemeal becomes more acceptable. But why is it important to get an on-block resection on a lesion that has a high risk of cancer? Where are we going once we've made that decision and we've got that specimen and we're getting a certain information? How's that going to eventually help the patient if they are diagnosed with cancer? Well, I think that the issue is many patients, they get along this pathway that becomes very confusing for us as providers and them as patients because there's like a possible, like at the edge, or if there's possible foci, but the specimen was fragmented. So I think where on-block is helpful very much so is in the staging, right? It gives you an accurate assessment and stage of what was just removed. And then you can manage them so appropriately from there as opposed to being like, there was possible submucosal invasion, but the specimen was in pieces. Or I think that's where the on-block, to answer your on-block question, that's where that's really helpful. But if you know from your histologic real-time assessment that there is no invasion, right? I mean, and most of the time we can do that. Then piecemeal resection is a great decision and we know those outcomes. There are some patients who even with submucosal invasion when it's present, because of the quality of the resection and the on-block resection, and the fact that we then take the specimen, we pin it to a flat surface, we get it appropriately analyzed, sectioned, evaluated by the pathologist, they may be able to avoid an adjuvant surgical resection that would not happen if we had piecemealed that lesion. Correct. Yes. Did not have it oriented. So I think for when you're thinking as an endoscopist and you see a lesion in the colon, the assessments that Tanya is making are leading you to this issue of, is this a lesion that if I resect it on-block and get it evaluated appropriately, I might be able to save this patient an operation, I think is what I'm hearing. Absolutely. There's also cases I get, like I resect scar sometimes because it's confusing whether or not the lesion was resected or not, right? I'm sure you get those referrals where the pathology is not convincing and there's this scar there, the patient's young. I mean, you don't want them to have surgery because of that. But so I, yes, my point there is if the more clarity we have with that pathology early on, we can sometimes be, it can be cured with endoscopy based on that, or you know they should go for surgery. I think it just helps us in those decisions. Now, as a, if I could be extend this in terms of thinking, how does the location in the colon affect this as a colonoscopist? I'm thinking about lesions. Does the same lesion in the right colon have the same effect on your thinking as a lesion in the rectum? How does the rectal location affect the risk of cancer and the risk of morbidity associated with surgery? I would say my biggest challenge with the rectal area is when the alternative surgery they'll do is TEMS, right? Or transanal excision, because we have this discussion a lot because we can resect with ESD or deeper, the rectum is like really fair game, right? And the alternative for the patient having an APR or an LAR is much different. I think that's what you're getting at. The surgeries are quite different. But what I also find with the rectum many times is that if the patient would go to surgery, many times they're just getting a transanal excision, which is in my mind, what we're doing with ESD in the sense of they also are not eliminating or assessing lymph nodes or removing mesopolon, you know? I mean, so I think that's where we really have a role in the staging and as well as potential therapy. In the right colon, I mean, a hemicolectomy still has significant morbidity and mortality, I mean, up to close to 1% mortality. So if we can resect this endoscopically, of course we should. If we can do it upfront where everything is clear, that's better because for all the reasons I said before, that confusion and that lack of clarity with pathology, I think is where we can do a better job as colonoscopists upfront. I think the threshold for doing on block should be lower in the rectum because of these reasons, because of the morbidity of the surgery in case of confusing pathology, if you do a piecemeal resection and there's a small focus of cancer. And also because, I mean, for the same lesion, I think the rectal ones or the distal ones have a higher chance of having invasive or covert cancers as being shown in multiple studies. So I think that's what I do is, and if I had to do an on block with an ESD or whatever technique, the threshold is lower in the rectum for these reasons. I think we're all pretty much on the same page. The rectum is, you know, Tanya has talked about very important features. We're gonna evaluate the vascular pattern, the surface pattern and the morphology to assess the risk of cancer. Rectal location itself is a risk factor for cancer. And especially the lesions that we see, I think in the rectum that most often raise concern that they're often granular lesions that have a nodule. And so it's this mixed granular pattern, the flat bumpy appearance that overall has a very low risk of cancer. But once a big nodule is present and then you're in the rectum because you've got a higher risk of cancer and you have a higher risk of surgical morbidity if you end up with a low anterior resection or an APR. So I think a fair number of people kind of practice that way, but what should be, you know, how we should approach these lesions. I think there's a lot of variability in opinion. Tanya, you were describing, you know, that I think when you see a non-granular lesion with pseudodepression, this is a lesion we should all worry about, right? Probably the highest risk morphology that we see, the non-granular lesion with pseudodepression. And you'll often do a hybrid EMR. But some of those lesions were 15, 20 millimeters. What are the other options for the person who doesn't do incisional type stuff? They don't make incisions. They basically, their tools are injection and a snare so that they can get out a smaller lesion with, you know, morphology that's considered high risk. Yeah, I think that if you use the snare tip, like you do the pre-cut with the snare tip and then you have a place to anchor it, the problem with that small, and I intentionally showed that smaller pseudodepression because you can get that, I think, right, in one piece with a snare. It's just that it will keep slipping. So you have to be really intentional. Well, how can I do that? And for me, the fastest, I think, was that circumferential and then cutting. But I also have had cases where you can put the tip of your snare, you make the small cut with the snare tip, and then you can lay that down, right? And that just gives you an anchor. And then you're gonna be basically pushing your snare out a little bit as you're closing to get that underneath. I mean, could you do FTRD in that? That's an option. I tend to prefer hybrid ESD over that option. But in people who are fluent in that technique over, I think that that size of this lesion was very amenable to that. What about underwater, Tanya? Go ahead, Amit, you can, maybe you wanna- So underwater is a good technique. I mean, I think for up to two to three centimeter lesions for on-block, I think underwater works well. The only problem with underwater is sometimes, because the colon is not insufflated with air or gas, it's sometimes difficult to see the edges. So marking the periphery can be helpful, but more and more I do underwater, I feel that it's a quick, efficient way of on-block resection up to three centimeters, I feel. I mean, that's what I've been comfortable with. I don't know if Doug has been doing larger ones. If there's a larger one, especially lateral spreading as a non-granular type flat lesions, which are large, and I can remove it in two or three pieces quickly underwater works out the best. I do think it's an option. And the literature clearly shows that you can get an on-block resection more reliably than you can with conventional EMR. Sometimes when there's a pseudodepression, it is tough because it just doesn't float up well. You want to get a big snare. I'm sure Amit's going to talk about this, but I think a theme that we're bringing out here is that your assessment of the risk of cancer is key. That's first, assess the risk of cancer. How much do you want to get an on-block resection? And then secondly, what are the tools that are available to you? Because that's going to depend partly on the size and morphology of the lesion. You can always test underwater and see how well it seems to float and whether or not you can clearly get the snare over it. And if you do ESD, that's always going to be an option. If the lesion is small enough, FTRD may be an option. And we're going to try to, I think, try to give people a feel for that as the day goes on about how to pick those different options.

lesion assessment

colonoscopy

resection decisions

endoscopic resection

lesion morphology

cancer risk

surgical morbidity