the podcast about I'm your host, Amanda Nicolley. This guest episode has been produced in conjunction with the Australian and New Zealand training board in colon and rectal surgery. This episode is the first in a series which is based on the work the Fellows have done for the Fellows Weekend which was held in Adelaide in August of 2023.
Our guest today is Henry Drysdale, who won the Philip Douglas Prize for this presentation, so congratulations to you. To start us off, would you like to tell us a little bit about yourself? Yeah. Thanks very much for having me on, Amanda. I'm a second-year CSSA and Zed colorectal fellow working at the Royal Adelaide Hospital this year. I did originally Victorian and did my general surgical training through Victoria. I went through... to Geelong, a regional hospital. Victorian did it too.
colorectal fellow years before starting the colorectal training program and I did my first year at Princess Alexandra Hospital in Brisbane last year and then now nearing the end of my second year at Royal Adelaide Hospital this year. and planning on going to the UK next year for a six-month robotic colorectal fellowship before starting consulting practice.
Excellent. Well, thanks so much for coming on to the podcast today to talk to us about malignant polyps. Do you want to start by telling us what malignant polyps actually are? A malignant polyp is by definition a polyp containing adenocarcinoma.
and that is defined as where invasion is breaching through the muscularis mucosa into but not beyond the submucosa. Importantly, malignant colorectal polyps are classified as T1 tumours by the AJCC but importantly not all T1 cancers are malignant colorectal polyps.
I think also importantly of note, Amanda, is that previously used terms like carcinoma in situ and intramucosal carcinoma are no longer recommended to be used because of the confusion it causes about whether or not this is in fact invasive disease or not. And so if you're seeing a polyp, you're doing an endoscopy and you come across a polyp, what endoscopic features make it more likely to be a malignant polyp?
I think this is an important area of practice because the likelihood of a polyp being malignancy is really important at the time of doing a colonoscopy. because it will determine about potential management at that time and also determine about whether or not you do things like tattooing and whether or not you proceed with a polypectomy at that stage. There's six key areas of an endoscopic assessment of a polyp which is used to determine the likelihood of it being malignancy. First one is size.
Second is morphology. Third is the surface pattern. Four is the location of the pole. Five is the presence or absence of the non-lifting side. And then sixth and finally is the narrow band imaging, the NBI classification, also known as the NICE classification. Do you want to talk a little bit about those different points? So what sort of size would make a polyp more likely to be malignant? What are the sort of cutoffs?
This is fairly straightforward for most of these polyps. The bigger the size of the polyp, the increased likelihood of malignancy. The important thing is to remember that a pilot is less than 5mm in size. has almost zero risk of containing invasive disease. And then there's a linear progression, bigger the polyp. Increased risk of malignancy, for example, a polyp between 16 to 25 millimeters.
has a 19% chance of containing invasive disease and a polyp greater than 35mm has a 76% chance of having invasive disease. And then you've talked a little bit about morphology. I had a really hard time getting my head around this when I was studying for my fellowship exam, but specifically this relates to the Paris classification. Can you talk a little bit about what the Paris classification is and how it relates to risk of malignancy?
The Paris classification is the most commonly used and I think the most useful morphological classification system. And it's used to describe not only the morphology of the polyp, but also then correlates that to the risk of it having invasive disease. So the Paris classification system breaks them down. The two main categories is that of protruding, and then the second is a non-protruding polar. Protruding polyps are also classified as type 01 polyp.
And then in the protruding polyp category, they're broken down into pedunculated and sessile polyps. And these are obviously the most common polyps that we encounter endoscopically. Importantly for protruding polyps, there is a linear risk between the size of the polyp and the risk of them having invasive disease. So the larger the polyp, the increased risk of it containing invasive disease.
then the non-protruding polyp are broken down into three different types of polyps and then classified as slightly elevated, completely flat and then slightly depressed without an ulcer. I think the most clinically relevant part of this is that the slightly depressed ulcers irrespective of size have a very high risk of containing invasive disease.
So whenever you see a slightly depressed ulcer, irrespective of the size of that polymer, there should be a relatively high index of suspicion for invasion and therefore biopsies and subsequent markings should be undertaken. I'll put a photo up on the Instagram page of the Paris classification just to help clarify it for you because the way that they classify it can be a little bit hard to understand but Henry's done a lovely diagram for us to make it easy to understand.
The third point that you mentioned earlier was the surface pattern or the kudo pit pattern. Another thing that I had trouble getting my head around. Do you want to talk about that for a little bit? Yeah, and again, there's different classification systems looking at the surface bit pattern, but the CUDA classification is the most widely used and I think the most useful for looking at that and essentially that's when you're looking at the overlying pattern of the mucosa overlying the polyp.
and the KUDO classification breaks that surface pattern down into seven distinct groups, ranging from KUDO classification 1, which is that of normal colonic mucosa, and then type 5 polyps, those polyps that have a higher risk of having invasive disease. And by using each of these different distinct seven groups, that correlates to the risk of invasive disease as an independent risk factor. Again, the most important of the two types of type 5 Kudo polyps, the first type of type 5 polyp.
is that when there's an irregular arrangement of the mucosa or the glands that are overlying the mucosa of the polyp. This is interpreted as having a risk of either high-grade or invasive disease. with an overall risk of invasive disease of about 30%. The other type of type 5 kudopolyps is where there's a loss or decrease of pits with an amorphous structure. and this also correlates to a high risk of either high-grade or invasive disease, estimated to be up to 90%.
So by familiarising yourself with these different types of pit patterns that overlie a polyp, these can be used as another tool when endoscopically assessing a polyp to see how likely it is to contain invasive disease. You mentioned whether or not the polyp lifts or the presence of a non-lifting sign. What does that mean? So a not lifting sign is when you inject a solution of fluid, usually gel effusion, as a colloid solution into the submucosal space, and this is usually done.
Often, sometimes as part of an assessment, but usually with the view to then go on to proceed for an advanced polypectomy technique such as AMR. And a non-lifting sign is when fluid is injected into the submucosal space that the polyp does not lift away from the submucosa. Obviously, if there is invasive disease beyond the submucosa, then that increases the risk of the polyp containing advanced malignancy beyond that of being T1 disease.
So injecting into the submucosal space can be used as an endoscopic method for assessing the polyp as well for the risk of malignancy. And lastly, you mentioned the narrowband imaging or use of narrowband imaging to assess the risk of malignancy. How would you do that? Yeah, this is used as narrowband imaging, which is available on most of the colonoscopy units that we use.
as a way of further examining the surface pattern of a polyp. The NBI classification, the NICE classification breaks down polyp surface patterns into type 1, 2 and 3. most interest for malignant colorectal polyps is that of type 3. and they're described as where there's an amorphous or absent surface pattern on the pollen. And as part of this, there may be areas of disrupted or missing vessel.
And again, this correlates using narrowband imaging as having an increased risk of their polyp containing invasive disease. And what's the difference between the Kudo classification and the NICE classification? It seems like this type 3 NICE probably correlates with those type 5 Kudo pit pattern classification polyp. And again, they're both looking at the surface pattern of Apollo.
KUDO is using light endoscopy, so without any added, whereas the NICE classification system uses narrowband imaging. As you said, there's a lot of similarities. between those two but just looking at slightly different ways of classifying that obviously using narrow band imaging for the NICE classification.
So let's move on. Let's say you've found your polyp and you've now assessed it using all of these tools and techniques we've just talked about. What options are available to you in terms of management of this polyp and what are you thinking about when you're considering which option would be appropriate? I think it's important to think about the principles of what we're trying to achieve with endoscopic management of a polyp.
In short, what we're trying to do is to aim for an on-block complete excision of Apollo. This allows for two important things. One is it has the highest chance of having complete endoscopic removal. And secondly, it allows for the most accurate histopathological assessment of the polypectomy. And so they're the principles that we're thinking about when we endoscopically approach a pollen. And then...
We think about the different options that are available to us at the time. I think it's always important to remember that if it looks like a difficult polyp tendoscopically removed and You don't necessarily yourself feel confident to have the skills to achieve those aims in polypectomy that you can always document through photos with a tattoo as well if needed and then refer it on or get some additional support at a later date.
The options for endoscopic management is first and most commonly is that of a simple snare polypectomy. Obviously, most of the time we look towards doing this as a cold snare polypectomy, but in polyps where we think of a high risk of bleeding and a lower risk of perforation, such as in the rectum, we can use diathermy with a hot polypectomy. to achieve this
That moves on. If it's not appropriate or we think there's a better way of dealing with it, we can then go on to more advanced endoscopic techniques. and they're largely with a colonoscopy using either AMR or ESD. And EMR is endoscopic mucosal resection that involves the injection of a solution into the submucosal space to lift up the polyp. It helps with both defining the edges of the pollen.
as well as raising the polyp away from the muscularis propria layer of the bowel and therefore decreasing the risk of thermal injury and subsequent perforation when you're performing a polypectomy and what AMR. allows us to do is an on-block resection of a polyp up to approximately 20mm in size. And for polyps that are greater than 20mm in size, AMR can still be done. However, this most likely has to be done in a pacemeal fashion.
ASD or endoscopic submucosal dissection is again another advanced polypectomy technique that involves injection of a solution into the submucosal space lifting up the polyp. and using an endoscopic needle knife technique to remove a large polyp. The advantage of ESD is that it offers the ability for on-block removal of larger polyps, including those that are greater than 20mm in size.
However, it is a more technically demanding polypectomy technique and it does have a much higher risk of perforation of the colon than both a snare polypectomy and EMR. When we're looking at these procedures being performed just for people who haven't seen them before Usually the EMR, the endoscopic mucosal resection, is just using that snare like you would for a simple polypectomy.
but basically taking a big bite if there's a sort of up to 20 millimeter polyp or often just taking it in pieces which is why if it's more than 20 millimeters you can't get a snare around it and you have to take it in pieces and the issue with that is that if it does end up being a malignant polyp
You don't have the margins of the polyp because you're cutting through the polyp. And it's harder for the pathologist to tell you if you have clear margins and what the depth of invasion is because they get given all these pieces. versus an endoscopic submucosal dissection. They actually use a knife and basically shave underneath the polyp using the endoscope. It's a pretty tricky procedure. I've seen some very skilled endoscopists do.
But as Henry's mentioned there, it brings the polyp out all in one piece and you can pin it out so then the pathologist is able to give you information about the margins, which means you can then make further decisions and it may be that you can avoid further resections for patients where... Maybe that answer wouldn't have been as clear with an EMR. So that's some of the considerations. Spot on. And what if the polyp is in the rectum? Are there any other options to ask if it's a rectal polyp?
Yeah, so rectal, we've got the option of trans-anal surgery, which is either via a TEMS or a TAMIS platform. TAMS stands for Transanal Endoscopic Microsurgery and TAMS stands for Transanal Minimally Invasive Surgery. There's a lot in Australia, a lot of geographical differences.
Different hospitals I've trained at use different platforms, but essentially they're achieving the same thing, the introduction of a device within the anus to dilate and to allow for the introduction of laparoscopic instruments through the anus. to allow for the transanal removal of a polyp or early malignancy. Again, this is another advanced technique to remove in most cases benign polyps.
but in some cases it can be considered for an early cancer. The two main ways of removing this is either be as a submucosal or a full thickness excision depending on the position of the polymer. and its endoscopic appearance and its likelihood of containing invasive disease. And just briefly for trainees that may not have come across this before, when we're talking about a full thickness excision, we're literally talking about taking the mucosa, submucosa.
muscular layers of the bowel wall. This can only really be performed if the polyp is located in the extra peritoneal rectum. So in the part of the rectum where when you do take the full thickness of the bowel wall, you are opening up into the mesorectum and not opening up into the peritoneal cavity. So that's one of the considerations when you're thinking about whether a full thickness excision is possible as to the location of the polyp and whether it's in the extraperitoneal rectum or not.
Some surgeons will close the defect that's left after a full thickness excision. And this is usually done transanally as the whole procedure is done using either a transanal suturing technique or using one of those platforms and using laparoscopic instruments to suture, which is quite difficult. or some surgeons won't close the defect in the rectum.
I think one of the areas of controversy then lies about what's better for a rectal polyp, about whether or not it should be removed endoscopically with either EMR or ASD, or whether or not a transanal resection of that polyp can be achieved. In my experience, I think there's still a lot of controversy around this and different centres that I've worked at over the past few years manage these differently.
with often colorectal surgeons tending towards using the TAMS or TAMS, whereas gastroenterologists who are performing their endoscopic procedures are more likely to do an AMR or ST on them. And in the general surgery fellowship exam, I don't think you have to have the answer. You don't have to know the answer for this, but I think it's just useful to know.
what the options are and be able to talk about them and what the different considerations are. There is this pretty sub-specialised kind of decision-making that goes into what would be appropriate for management of these complex So let's say you've used one of these advanced endoscopic techniques and you've removed the polyp and you are looking at the pathology report in the MDT and it's come back as a malignant polyp.
What are the histopathological features that might influence whether this patient needs subsequent management for their polyps? And just before going on to the event, I think it's good to try and think about what we're trying to achieve or what the questions we're trying to answer with our histopathological assessment of our polyp. I think the two most important questions is once a malignant colorectal polyp is confirmed is what is the chance of local residual disease.
and what is the chance of having nodal disease. They're the important things to consider when we're looking at the different histopathological features. There's six key histopathological features that I think are important when interpreting malignant colorectal polyp pathology. First is that of resection margin. Second is the morphological classification.
Third is the histological grade. Four is if there's cribriform histology. Five, the presence or absence of tumour budding. And six is the presence or absence of lymphovascular invasion. We might talk about those in a little bit more detail. So firstly you said resection margin. What is an acceptable resection margin for a malignant polyp and is it the polyp that needs to be clear or is it the malignant component that needs to be clear?
Yeah, so the resection margin varies, but overall, the most common consensus of a clear resection margin for a malignant polyp is greater than one millimetre. So when the pathologist inks the margin of the polyp and then looks at it, if that is greater than one millimetre away from that polyp, that would determine they have a complete resection margin. Again, this is often a difficult thing in my experience when we talk about these polyps and the MDT for a pathologist too.
accurately and reliably be able to comment on the resection margin. So we often take what the pathologist reports as the resection margin. in conjunction with our endoscopic assessment of the polypectomy, especially when it's being conducted pacemaker. Definitely. And you mentioned the morphological classification. Do you want to tell us a little bit about the Haggart and the Kikuchi classification? HAGT is the most commonly used classification system for pedunculated polyps.
The agate classification system breaks down the level of invasion in a pedunculator polyp into four different levels from one to four. Level one being invasion into the head of the polyp. level 2 invasion into the neck of the polyp. Level three, invasion into the stalk of the polyp. And level four, being beyond the stalk, but not into the muscularis proprivate layer, so not beyond the submucosal layer.
The clinical relevance of this is that level 1, 2 and 3 have relatively low risk of residual or nodal disease. whereas haggard type 4 have a much higher risk of having residual or nodal disease up to 25%. So therefore, using that morphological classification system, that can be useful to help us to estimate the risk of residual or nodal disease.
And when would we use the Kikuchi classification? Kikuchi is used for sessile polyps and it breaks down into three different types of level invasion in Kikuchi polyp. SM1, SM2 and SM3 and they each correlate to the depth of invasion into the submucosa of the polyps. SM1 is invasion into the upper third of the submucosa. SM2 is invasion into the middle third of the submucosa and SM3 is invading into the lower third of the submucosa.
The difficulty for pathologists interpreting this is that the only way to assess that relative depth of invasion in the submucosa is for muscularis propria. to be present within the resected specimen and often for our polypectomy specimens this is not the case. Kikuchi's original work used the depth or the relative depth of invasions of subcucosa to correlate with the risk of residual disease and that percentage is quoted as SM1 as about 1%. SM2, 9% and SM3, 25%.
You mentioned a few other histopathological findings, so histological grade, crib reform histology, tumour budding and lymphovascular invasion. Can you briefly summarise how those correlate with the risk of both residual and nodal disease? So for grade, the worse the grade, obviously the more concerning that is for the risk of residual or nodal disease. Poor histology in particular is an independent risk factor for nodal disease.
Presence of crimboform histology is also a poor prognostic factor as well as the presence of tumour bunny and the presence of lymphovascular invasion are both poor prognostic factors for malignant colorectal polyps.
And so if you have a patient in the clinic and you're looking at all of these Are there any other tools that we have available to us or you use in your clinical practice to help with some data or some numbers you could talk to with patients to help inform the decision about whether or not to proceed with a resection or whether or not to continue to monitor them. Yeah, I think this is a difficult area of practice trying to draw together these histopathological factors to try and then correlate.
to what we should do in clinical practice. And essentially what it boils down to and what we need to try and achieve is some estimated risk of percentage. for the risk of residual local or nodal disease. I think importantly, through my rating and looking into this topic, that it really isn't an exact sign. that these are largely estimates of what we're trying to look at, and most of the data is retrospective data. But the principles are that some pathological factors carry more risk than others.
I think the factors that are of most significance for looking at the risk of residual nodal disease is if there's involved surgical reception margin. high at level 4. Cucucci level SM3 and poor tumor differentiation. All of those factors are the highest level of concern as a poor prognostic factor.
and all carrying independent risk factor residual disease of at least 15%. Recently, a risk calculator was developed between a team of clinicians based out of the Royal Brisbane and Women's Hospital and a team of pathologists based out of the Royal North Shore Hospital and it's published
polyp.com and on that website you can also see their data and some of the publications that they've made but it's a really helpful tool because you can put in all of the individual patient in front of you's information about their malignant polyp And it'll spit out at you a risk calculator, which gives you their risk of both local and nodal residual disease. And this is really helpful in the clinic when you're trying to have a discussion with a patient about what to do about their polyp.
I think those calculators are useful and there's a number of different ones. Marks also has a calculator for malignant colorectal polyps as well. And again, they're just trying to bring that data together. into a tangible risk that not only informs us, but as you said, is really useful when you're talking to a patient to be able to counsel them about the risk benefit, which a lot of the subsequent management boils down to.
So for the next part of the podcast, would you like to talk through some cases and we can talk about what the individual considerations are and what you might suggest would be the appropriate management pathway for each patient? Yeah, sounds good. Let's say it is a 55 year old gentleman who's come in after a positive bowel cancer screening test.
and he's had a polyp removed. Firstly, the endoscopist thinks that they've completely removed the polyp. They did a nice polypectomy with a cold snare around the stalk and they think that they have completely cleared the polyp. So the pathology comes back and it's a tubulovillus adenoma containing low-grade adenocarcinoma. It's a haggot. 2 polyp with some evidence of lymphovascular invasion and a clear resection margin.
What would be the considerations for this case in terms of counselling the patient and what might you suggest? Damn. First of all is just looking at the polypistologies as well. Using a calculator or a table or using the data, you can try and estimate what that risk of residual, local or nodal disease is.
If I was to plug that into the table that I'd constructed based on my data, That polyp specifically would have two medium risk factors with an overall estimated risk of residual local or nodal disease of greater than 20%. That places it into a very high risk for the risk of both. local residual as well as nodal disease. And using that and calculating the percentage, we can then go on to determine subsequent management of that polyp. So you think that this is a moderate to high risk polyp?
Let's say it was in the mid-rectum. What are the management options? What should you do with this patient from here? I think the principles that are going to guide subsequent management is where the polyp is located and then the individual patient circumstances in terms of talking about the location of the polyp, the risk. profile for subsequent management is very different to that of a seagull polyp versus a mid-rectal polyp.
And what I mean by that is that obviously a right hemicolectomy is a lower risk operation than doing an ultra-low anterior section, but also importantly, it has a much different risk of morbidity for the patient as well. So that polyp needs to be interpreted in a different location within the colon or rectum because that will guide subsequent management. And then secondly is the individual patient circumstances.
And I think I'd broadly classify that into what the age of the patient is, what the comorbidities of the patient is. And also, lastly, but certainly not least, is the patient's approach and tolerance to risk. I think the important thing to remember about all of these malignant colorectal polyps is that most of them have been successfully dealt with endoscopically. And even in the high risk or the very high risk polyps, most of the time there is no local residual or nodal disease.
And the operations that we perform do all carry risks and they are associated with potential long-term functional consequences. So often what the patient's tolerance for risk is and what they want to do will significantly influence how we go on to subsequently manage these polyps. I was reading a recent UK study over the last few years looked at their last 300 segmental resections for malignant colorectal polyps. and only 18% of those specimen contained residual disease.
And that's for polyps that are the highest risk have gone on to have operative management. So it is always important to remember. consequences of leaving local disease or not detecting nodal disease can be significant.
that the vast majority of these patients will not have local residual or nodal disease and most of them are being cured with their endoscopic management. Yeah, in clinic, I always say to the patient, there's a risk that we do this operation to absolutely no benefit to you, that we don't find any cancer.
And I think that's a really important discussion to have with the patient. I think the other thing to remember that these are malignancies, right? So if you get a diagnosis of a malignant polyp, you need to take a step back and say, well, this is a cancer. I need to stage the patient. Got to make sure you get a CEA, do a CT staging scan and an MRI if it's in the rectum.
And that's really important for staging both their local and distant disease and may help inform your decision making because if you do an MRI and you see enlarged nodes, then that might push you to a resection, for example. Exactly. and obviously with any other malignancy as well like this, discussing an MDT is going to be important as well because these are really a multidisciplinary decision-making that's involved.
and by reviewing that pathology, reviewing the imaging with the radiologist and getting a group consensus on the risk of malignancy is important in the management of these patients. Let's say that this patient has been discussed at the MDT and you've had a long discussion with him and he's keen for some definitive management for this polyp. What options are there to him for definitive management?
And it's largely been broken down into, first of all, segmental resection, so removing the affected area of colon or rectal where the polyp is. Two is transanal resection. So what we mentioned before about a TEMS or TAMIS resection of the scar. And again, this can be either submucosal or full thickness. Thirdly and certainly not least is surveillance of the patient so electing to not go ahead with any further operative management of the polypectomy site.
And then lastly, but not commonly used, is adjuvant radiotherapy can be used for the management of milling up rectal polyps. as an adjuvant management. But again, that's not commonly used. It really is broken down into whether or not we survey these patients, whether or not we cut out the affected segment of the colon or eipman or excise the scar with TAMS or TAMIS.
And just to clarify for the trainees listening in, if we did a Thames or Tamis, we're only addressing the local disease. So you're not addressing the risk of nodal disease because you're not removing the lymph nodes. Exactly. And again, as we mentioned before, that patient would have had an MRI. And when you're going to consider doing a transanal resection of the polypectomy scar, you've already assessed.
the lymph nodes with an MR rectum. And then, as you said, the transanal resection is just to excise the polypectomy scar, but it does not address the lymph nodes. And let's say you decide that this patient has a high risk and he's keen to undergo surgery and he's had all his staging scans and there's no evidence of any metastatic disease so he goes ahead and has his ultra low. What sort of surveillance would you put him on post-operatively?
And importantly, as you mentioned before, that these are all cancers and they should be subsequently survived as cancers. And this is a combination of surveillance with tumour markers. with imaging and with colonoscopies following the Australian guidelines. Regularly checking CEA colonoscopies and CT chest, abdomen and pelvis should be undertaken to make sure there's no evidence of any recurrence.
So it's a big topic. Did you want to give us a bit of a summary of some of the key points or things that people listening should take away? I think areas of interest for me are when we're thinking about the management of malignant colorectal polyp is trying to differentiate between the risk of local residual and nodal disease. Often this isn't clearly spelled out in the literature and the data on these polyps, but I think they are two different things and two different entities.
And I think that when we're managing a malignant colorectal polyp, there is a differentiation between trying to work out what the risk of local disease is versus the risk of nodal disease. Going back onto that malignant rectal polyp case that we were talking about before. For example, the risk of local residual disease can be determined using a TAMIS resection of the polypectomy scar and the risk of nodal disease can be assessed using the MR rectum.
And whilst we often bunch these together when we're looking at our risk calculators and when we're considering these polyps, they are actually two different distinct things and we should keep thinking about them as two separate entities.
And what advice would you give to trainees or colorectal fellows who are trying to get their head around the management of malignant polyps? I think obviously we all come across these patients and we all deal with malignant colorectal polyps in everyday practice. And I think when you come across these cases in clinic, it's good to try and sit down and look out and work through these cases ourselves.
and to look behind, look into the histology. I always find it interesting to talk with a pathologist or review it in MDT to look at those different risk factors and actually think about how they actually correlate to the risk of disease. always stepping back and thinking about Why we're doing a subsequent management is also important. For example, looking at and seeing whether or not there is malignant nodal disease.
post-resection, it's important to think about why we're doing that, why we're trying to detect nodes, because... We know that, by and large, for the management of colorectal cancer, that the resection of malignant nodes is largely a prognostic indicator. by trying to work out whether or not there is residual nodal disease that's largely prognosticating their cancer to provide them with adjuvant treatment.
Adjuvant treatment in stage 3 colorectal cancer has for all comers about 30% risk reduction in the risk of subsequent disease. But not all patients are going to be candidates or going to want to have antifact chemotherapy to decrease that risk of disease. So thinking about what we're actually trying to achieve when we're doing subsequent management of colorectal polyp is important when we're considering management of those patients.
Well, thank you so much for taking the time to talk to us today. I'm sure given this is the third time in the last few months you've talked about malignant polyps, you're probably absolutely sick of talking about it. So I do appreciate you coming on to the program. Thanks for having me, Amanda. So very briefly before we finish up this episode, I just wanted to mention a little bit more about the Australian and New Zealand training board in colon and rectal surgery.
This is a two-year post-fellowship training program that is jointly run by the Colorectal Surgical Society of Australia and New Zealand and the section of colon and rectal surgery of the Royal Australasian College of Surgeons. This program offers trainees a structured educational and training experience to achieve expertise in the understanding, diagnosis and management of diseases of the colon, rectum, small bowel and anus.
There's two main program streams, a two-year program which focuses on clinical practice and a three-year program which is made up of one year of research as part of a higher degree and then two years of clinical practice. And there are Australia and New Zealand training board in colon and rectal surgery accredited training units across Australia and New Zealand.
And each of these units has a strict accreditation program. So you know that the hospitals you're being sent to are really excellent training units that provide a really comprehensive training program for fellows. It's a really exciting thing for me to be able to partner with them and to be able to provide you with episodes around the different training topics that we cover at our trainees weekend because these topics were really comprehensive and so well researched by the trainees.
So I hope you learn as much as I have from listening to Henry today and I hope you're looking forward to the upcoming episodes as much as I am. It's time to close up. If you have any comments or feedback, send us a message at firstincisionpodcast. or follow us on Instagram at firstincision. Happy studying!