Navin (3:02)

So, Seth, those are such important points. It's so critical to get a detailed family history and to remember, not just ask about colon cancer, but also advanced polyps. And when you were discussing the advanced polyps, I liked how you broke it down between advanced adenomatous polyps and advanced sessile polyps as well, because there are two different types of precancerous polyps, and both of those, if they have those characteristics that you said will constitute an advanced polyp and also a positive family history. So in this case, let's say the patient finds out this mother had just a small adenoma, let's say it was like 3 millimeters that was removed, so below that 1 centimeter threshold. And no other first degree relatives with colon cancer or advanced polyps. So based on this information, when would you recommend he start colon cancer screening?

Dr. Sith Saker (3:48)

Yeah. So based on the current guidelines, he'd be considered average risk for colon cancer and should start screening at age 45. But, you know, for example, if the mother, she had a 3 millimeter polyp, but if it was sort of 1.5 centimeters or had any of those advanced features and she was diagnosed with that polyp at even age 35, then you would think about starting at 25 for him. If it was diagnosed at 60, then you would think about starting At 40 for him.

Navin (4:17)

Perfect. So you basically just take the earliest time, whether it be age 40 or 10 years before the age of diagnosis, like he just went through. All right, so now that we discussed when to start screening, what are the options available to screen for colorectal cancer?

Dr. Sith Saker (4:31)

So there's, there's a ton out there. And when I think about counseling patients for colorectal cancer screening, I try to frame it around prevention and adherence. And like we discussed before, colorectal cancer typically develops either from adenomatous or serrated polyps over many years, which gives us a great window to either remove precancerous lesions or detect cancer early when outcomes are the best. So for Average risk adults, which is very important. So no prior history of polyps and no family history. As we discussed prior, there are two broad based screening strategies. Either you can go with colonoscopy, direct visualization or stool based testing. Both are guideline endorsed. Neither is better than the other and the effectiveness of either strategy depends heavily on patient adherence. Colonoscopy is the most comprehensive option. It visualizes the entire colon and allows for immediate pulp removal, which is why it's considered both a screening and preventative test and one that we usually prefer. A normal exam generally allows for 10 year interval before the next one. The trade offs though are that you do need to go through that bowel preparation, need for sedation, a small but real risk of complications such as bleeding or perforation outcome perspective. It offers the lowest risk of interval colorectal cancer when performed with good quality metrics. The other big group are the stool based tests such as fit testing or cologuard, which is a multi targeted stool DNA testing. They're non invasive and completed at home which improves patients doing it. These tests detect occult blood or abnormal DNA shed by the advanced adenomas or cancer. Their key limitation is that they do not prevent the cancer and they do not remove any polyps. And they require strict adherence to repeat testing at regular intervals. But the most important point is that any positive stool based test mandates a short interval diagnostic colonoscopy and that's really important for patients to understand.

Navin (6:21)

Sif, that was a really helpful overview of the available screening tests and the guidelines behind which tests to choose. Are there any other screening tests that you use in certain patients or scenarios that we have not yet discussed?

Dr. Sith Saker (6:32)

Yeah, one that comes up from time to time is CT colonography. It's actually most commonly used when a colonoscopy is incomplete or technically not feasible to do. This can happen when there's a redundant or very tortuous colon, fixed angulations from prior surgeries or patient intolerance from sedation or from the procedure. It provides a non invasive cross sectional evaluation of the entire colon. It can identify clinically significant polyps, typically those that are greater than 5 millimeters, but unfortunately can't really identify any of those really flat lesions that sessile serrated polyps can be, or any polyps less than 5 millimeters. The key limitations are that it still does require bowel preparation like a colonoscopy, but doesn't allow for biopsy or polyp removal. And any concerning findings still require follow up colonoscopy. In practice, its highest Value is as a completion study after an incomplete colonoscopy to avoid any missed proximal lesions from where you couldn't get past.

Navin (7:31)

Excellent. I think it's helpful just to review the bowel preparation since you've mentioned it a few times, both with obviously colonoscopy, but as well as CT colonography. And so in our institution and most other institutions, this involves being on a clear liquid diet the day prior to the exam and then towards the later afternoon to start the actual bowel preparation. Our standard is to use a Miralax based preparation in which the patient takes a full bottle of Miralax and mixes it in 64 ounces of clear fluid. And we found that actually the split preparation, where they then split the dose between doing 32 ounces of that prep that afternoon and then the second 32 ounces five to six hours before the procedure, leads to better visualization for the colonoscopy. So it indeed it is a to do for the patients to accomplish before their exam. And Seth, can you comment about the importance of having a CLE bowel preparation for the colonoscopy?

Dr. Sith Saker (8:32)

Yeah, it's paramount of importance. It really sort of helps in making sure that there's no small polyps or lesions that are missed. And it just sort of makes the whole procedure much more comfortable for the patient as less time is used, sort of getting through the colon and it gives such a cleaner view while looking at the colon sort of on withdrawal and looking for polyps. And you know, unfortunately, if the preparation is not great, sometimes we have to repeat the colonoscopy in short interval or are not able to clear them for that full 10 years that we ideally like to if it's a normal colon. So while it is sort of, you know, an undertaking for the patient to undergo right before the colonoscopy, it's so important to do it very carefully and well.

Navin (9:13)

Absolutely. And I love how you touched on the quality metrics of a colonoscopy. I think in addition to having an adequate bowel preparation, so much of this hinges on the endoscopist taking their time when surveying the colon, looking in between folds and. And Seth, you can, you can comment on this. Where are the most high risk lesions often missed during a colonoscopy? And why do we pay special attention to that area of the colon?

Dr. Sith Saker (9:38)

Yeah, so there's a couple places I really pay careful attention through the colon because it's so easy to miss lesions or polyps there. One of them is right behind the ileocecal valve. Right. That the end of the colon sort of polyps can definitely be flat and sort of right behind there. And on the right side are the ascending colon and the cecum. There's definitely a higher risk of having sessile serrated lesions, which are sort of these flatter lesions that are much easier to miss. And then the other big spot is right at the hepatic flexure, right where that turn is made into the ascending colon. Just because it's sort of a blind spot, as if you're driving, it's sort of a blind spot on a colonoscopy. So really taking time, looking at that area at least two to three times with careful withdrawal, and then spending sort of adequate time withdrawing throughout the whole colonial. Our metrics, our quality metrics are always sort of improving. Now we're trying to hit at least 10 minutes, 8 to 10 minutes on withdrawal. And that's really important because these lesions can be very small. They can be very flat and very easy to miss. So taking your time is really important during a colonoscopy.

Navin (10:39)

That's great, Seth. Yeah. When I have medical students come shadow me an endoscopy, I know I have them shadow you as well. I think they're always surprised by how small and subtle some of these polyps are. So it truly takes an experienced eye but just extra time to find these lesions that can otherwise be potentially missed. So this was great. I want to get back to our case, and let's review. So based on your knowledge of the guidelines, you recommend that this patient start colon cancer screening at age 45, as he's considered average risk for CRC. Together, you decide on a plan for a screening colonoscopy. At that time, as he is a healthy candidate and he's motivated to undergo a diagnostic and potentially therapeutic procedure. He also feels reassured by his average wrist status after your review of the guidelines. So with that sith, can you conclude our episode with some RTL pearls from today?

Dr. Sith Saker (11:28)

Absolutely. I think the biggest pearl, and one that's really important to understand, is that it's important to learn your patient's family history. You know, obtaining any patient's family's procedure and pathology reports if needed. A lot of times, sort of, those advanced adenomas can be missed in the patient's family history, as it's not something often mentioned to children. Colon cancer patients usually know their family history of but those advanced adenomas into review. Anything that's greater than 1cm in size has tubulo villus or villus histology. High grade dysplasia or any sort of advanced sessile serrated lesions are really important to know because that puts them at sort of the same risk as having colon cancer in their first degree relatives would and starting screening at age 40 or 10 years before the diagnosis. So that's a really important pearl to understand. And then it's, you know, there are a lot of different colon cancer screening strategies. Colonoscopy provides both that screening and diagnostic aspect of removing the polyps and lesions at the time of the procedure, but understanding that the best strategy is the one that the patient is going to follow. So if they're reluctant to get a colonoscopy but will undergo stool testing, I think it's important to discuss that with them. Talk between fit and sort of DNA based, such as cologuard, do it at the appropriate intervals and you know, most importantly, if it does become positive, refer them for that colonoscopy so that we can do more of a diagnostic look to try to see, you know, why it turned positive. If there's a large polyp or anything like that that needs to be removed.

Navin (12:57)

Those are some great pearls, Seth. And you know, I do think the bowel preparation is the most challenging piece of the experience for patients. And when I have patients who come see me for the first time for their colon cancer screening and colonoscopy, it's often that first step of just getting through the prep and then once they're actually here for the procedure, everything like you said, provided that it is done carefully and with high quality, goes very smoothly almost all the time. So the ability to screen for colon cancer is so, so important. So I really appreciate you going through all the different options and especially that take home point that the best screening strategy is the one that your patient is going to follow through with. So thank you so much, Sif. This was great. We had such a nice time discussing colon cancer screening in depth with you and I look forward to having you back on RTL in the future.

Dr. Sith Saker (13:46)

Thank you for having me.