Gastroenterologist Aparajita Singh, MD, discusses existing and emerging screening tests for colorectal cancer and evaluates their efficacy. She covers screening recommendations, modifiable and non-modifiable risk factors, and the latest colon polyp surveillance guidelines.
Hi, everyone. Thank you for joining us. Um, today, we have Doctor Aparattita Singh. She'll go over, um, beyond the colonoscopy, colon cancer screening in 2026 for primary care. And without further ado, I'll go ahead and pass it on to Doctor Singh. Thank you so much, Virginia. Um, I appreciate the introduction, and it's my honor to speak to you all about colon cancer screening in 2026. There couldn't be a better time to talk about it, um, especially when we have so many colon cancer screening tools, uh, beyond colonoscopy, stool tests, blood tests. Which one is the right test for your patient? Um, let's talk about it. Uh, so, I'm a gastroenterologist, uh, at UCSF and I direct QUI for GI division. And I'm also the director for UCSF Lynch Syndrome Center here. So within the next 50 to 60 minutes, um, I will be talking to you uh about epidemiology of colorectal cancer and existing and emerging screening tests, and when to start, start and stop screening for colon cancer, and also what are the new colon polyp surveillance guidelines. Here are my disclosures for this talk. So this audience is very well familiar that colon cancer, the lifetime risk is about 4% in this country. Around 4.3% for men, and very close, around 3.9% for women. It's the second leading cause of colorectal cancer-related death in this country, and it's the 3rd most common cause of cancer in the US. Um, we have about 147,000 new cases diagnosed every single year. And about 50,000 of these individuals die of colorectal cancer. Colorectal cancer screening does save lives. We have seen that early detection, for example, 5 year survival for early stage colorectal cancer is about 91%. And this drops to 13% for metastatic advanced colorectal cancer. Despite various colorectal cancer screening options being available, close to 40% of eligible adults are not up to date with screening, and I hope that we can change the needle now that we have so many options. So, what are the modifiable risk of colorectal cancer? Um, we know that smoking, alcohol, excess body weight, physical inactivity. Red meat, processed meat, diet low in fiber, low in fruits and vegetables, low dietary calcium, and low vitamin D, many of these are associated with increased risk of colorectal cancer. So when you see your patients, as we offer for colon cancer screening options, it should also be a routine practice for us to assess for the modifiable risk factors and counsel accordingly. What are the other risk factors? We know age, family history, various genetic cancer syndromes like Lynch syndrome, inflammatory bowel disease, and some less commonly known are history of abdominal radiation, if your patient had, uh, when they were children or young adults, HIV, acromegaly. Kidney transplant, and other transplants, and the resulting immune suppression, diabetes, cystic fibrosis. We do have some data and guidelines to modify our screening guidelines for some of these risk factors that I will discuss, but um, majority of these risk factors, we do not modify screening recommendations, which we may in the future as we may modify recommendations for each patient. So, what societies put forth colorectal cancer screening guidelines, there are several societies that have So, um, published their um consensus recommendations and guidelines over the last couple of years. They are listed here. And my talk today will be a summary of these recommendations. Most of these agree on, uh, most of the guidelines with minor variations. Uh, so I'll be sharing a summary recommendation that most of us follow here at UCSF. So first question, when to start screening, whom and when? Now, the age to uh to start colorectal cancer screening is 45. Most of the societies agree on that, and it should be offered in adults who are in good health with a life expectancy of more than 10 years. American College of Physicians, they still suggest to start screening at age 50. Uh, other societies recommend starting at age 45, given the increasing incidence of colorectal cancer in younger individuals. So what testing options exist? The list is growing. We have um stool-based-based testing. So we have high sensitivity, VA FOBT testing, that's old fashioned, we all have heard about, fit test. And multi-target stool DNA test, also known as Cologuard, and a new version of Cologuard is about to come, known as Cologuard Plus, which will replace the older Cologuards, and multi-target stool RNA testing, which is known, the brand name is FloSense. The direct visualization tests, colonoscopies, flexible sigmoidoscopy, CT colonography, also known as virtual colonoscopy, and a colon capsule endoscopy, um, is also an option. What are the blood-based testing? So we have two commercially available blood-based colon cancer screening options, um, also known as cell-free DNA testing or liquid biopsy. And we have Shield and Simple screen from two different companies. So let's do a little bit of tumor biology for colorectal cancer screening. So, as we know, any colon cancer formation is a result of various mutations that happen in those colonic cells, and that is because of the various somatic mutations, also aberrant methylation, changes in genetic expressions, and as the tumor grows, some, not all of them will bleed. And these tumor cells can also invade the blood and go, you can have these, both, uh, these tumor markers in your blood as well. So for screening purposes, we can utilize um the, the, the DNA markers that shed in the stool, so we can use the stool test for those DNA markers, or we can use the stool for the blood that uh uh results from bleeding for these large polyps or tumor. So, uh, different testing methodologies, as you can see, are testing for different um markers from these large polyps or colon cancer. And that is important to understand, um, as we, uh, offer various testing and understand their screening, uh, their sensitivities and specificities. So here you can see that since blood tests are testing for circulating tumor DNA markers, a very early stage, small polyp or even early stage cancer that is non-invasive could be missed by these blood tests, um, uh, circulating tumor DNA markers. And similarly, uh, small lesions which are not bleeding could be missed by a fit test, which is based on, uh, which is detecting blood in the stool. So, let's talk about these uh colon cancer screening tests that um we discussed. So, uh, fecal occult blood testing that was based on GAAC is also known as GFOBT, a GAA-based FOBT test, not favored tests in most of the societies, except a few do not. Uh, include this, um, in their, um, uh, colorectal cancer screening options. Um, so it detects heme in stool via peroxidase activity, and it does require dietary restriction. So patient needs. To stop eating red meat and make some other changes um uh for this test, and it requires 3 separate stool samples um because the bleeding could be intermittent. So 3 consecutive stool samples should be collected and it detects bleeding from the entire GI tract. Because if you have a gastric ulcer that's bleeding, the heme from that gastric ulcer bleeding is stable along your GI tract. So it can be detected by GFOBT testing as well. So not very specific to a colon cancer that we are trying to detect. And in the past, we also did digit digital rectal exam in office. So, while you have the patient in the office, the best time was to do a rectal exam, do a FOBT card. Now, it shouldn't be used for colorectal cancer screening purposes, uh, because of low sensitivity and uh um uh high miss rates. So now, moving on to a better version of fecal occult blood, blood testing, which we have had for the last many, many years, is called FIT test, also known as IFOBT which is immunohito uh uh um uh um. Uh, based fecal occult blood testing, which uses antibodies. So, unlike guaiac paroxidase, um, based testing, it's an immune-based testing that's using antibodies to detect globin protein of uh human hemoglobin. So it's a very specific, less likely to have false positivity. Uh, so, therefore, since it's a very specific test, no dietary or medication restrictions for the patient, they can continue their aspirin, for example, if they take it. And here in this country, it's recommended to be repeated, um, uh, one sample once a year. In some other countries, it's offered every 2 to 3 years. And, uh, despite, you know, we discussed that GFOBT is in some guidelines, fit test has largely replaced wire-based testing because of its superior sensitivity, easier sampling, and higher patient adherence because of lack of dietary restrictions. And also a note that fit can be positive due to an upper GI bleed, which is a rapid, a large amount of rare scenarios that wouldn't be applicable in general average patients. Um, so it's a very good test for routine average risk person, uh, annual colon cancer screening option. So now we move on to what else we have. We have Cologuard, which is a fit DNA. So, it incorporates uh uh testing for the globin we do for fit, plus it also looks for some DNA markers. And um this is a home collection uh stool test. So once you place the order, patients receive a kit directly from the company at their home. And unlike a fit test, They have to collect the entire stool sample. So here you can see there is uh um uh they get a little kit that sits on the toilet seat and they put the ball in here and the entire bowel movement has to be collected in the kit. Then they pour this um the um preservative on top of the stool, and before that they have to scrape out a tiny amount of their stool for this little tiny tube that's in there. And then, then they put the agent, uh, preservative on top of the stool and seal it all up, put that in the prepaid box and mail it back directly to the centralized lab uh for Cologuard, which does all the testing uh for their Cologuard stool samples. So, um, Cologuard is recommended for, again, average risk adults aged 45 to 85, and it should be repeated every 3 years. USPSTF does recommend it to be used every 1 to 3 years, but in general, most other societies uh suggest using it every 3 years, which is a common practice. And what this test does is it uses a logistical regression algorithm to generate a positive or negative results, and it tests both hemoglobin in the stool like a fit test and tests various DNA markers. So it's looking for chaos mutations, uh, which is a cancer. Associated gene mutation very commonly seen in colorectal cancer and it's also looking for methylated BMP3 and NDRG4. So these are genes with abnormal promoter methylation in colorectal cancer, uh, which happens because of epigenetic changes in the tumor. And also test for beta actin, which is just more for a control that adequate human DNA was uh was there in, in the sample. So, now moving on from Cologuard test process to the, the performance. So it's about 92% sensitive for colorectal cancer, but the sensitivity for advanced adenoma is actually uh a lot lower to 42%. Which we can understand because of, unlike cancers, advanced adenoma may not have bleeding or shedding of the, the DNA markers that it's testing. And um an important caveat is this test result does not differentiate that when they say positive, they don't tell that it was a fit that was positive or the DNA markers. So the result is very summative. And the next generation version um of Cologuard uses some additional methylation markers, and it will be uh released and will replace the existing Cologuard, will be known as Cologuard Plus. So now moving on from Cologuard, one stool uh uh test for CRC to a different stool colorectal cancer, the new kid in the block is Colosense. So, it's similar to Cologuard in the sense, it does test for a hemoglobin, the blood in your stool, uh, like a fit test, like a Cologuard test. But unlike Cologuard, it's not looking for DNA markers. It's looking for RNA markers. So RNA, you know, they, uh, they are messenger molecules that guide protein production in the cells. And then when cancer cells have abnormal gene activity, they result in aberrant RNA and color senses. Protects shed colorectal cancer cells in stool with these abnormal RNA patterns and um it's um a test that should be repeated every 3 years like Cologuard and it's also um uh approved, FDA approved for use in average risk individuals. So now, moving on from uh 23, actually, stool-based testing to blood-based testing. What do we have commercially available? So we have 2 commercial blood tests available that you can order in your patients today if you like. And they are um garden uh shield blood tests. And the other one is from ren simple screen colorectal cancer uh tests. Both of these are looking for cell-free DNA markers in the blood. Another blood test we had in the past is epiprocholon, which looked at 79. That shouldn't be used in practice now, given it's low, much lower sensitivity. And um ACG had a statement that it suggested using, uh, suggested against using epiprocholon septine test. So the test, the blood test, if you use in the practice should be the shield or simple state. So, what do these blood tests uh uh look for? So the test methodology and the exact genomic markers that the test is proprietary, but we know that they are looking for cell-free DNA using multimodal approach. So, they look for somatic mutations uh uh that is shed. From the tumor in the blood and aberrant methylation markers and uh uh looking for various DNA fragments, uh, their sizes and distribution pattern through a complex algorithm, they are able to identify patients with um who have, um, you know, advanced age colorectal cancer. Um, for screening purposes. So these both blood tests are recommended every 3 years for, again, for average-risk individuals age 45 to 75. And um we are excited to see that these blood tests for screening may improve participation in screening programs because of perceived ease of use. When you talk to a patient, offering a colonoscopy or a, a stool test may not be as exciting as a blood test, but there are caveats that um We have seen based on their sensitivity and specificity data and various, we had a recent publication for a modeling study that long-term modeling projections showed that uh problematic screening with current blood tests every 3 years is, is substantially better than no screening. And it will result in lower prevention rates for colorectal cancer or deaths um than fit test, Cologuard, or colonoscopy. So again, what we saw in these modeling studies that if you have a patient who does not, who doesn't want to do colonoscopy, who declines, uh, you know, fit test or, you know, Cologuard, Coloense testing. And they wouldn't be open to any of these testing options. Instead of no screening, that is the person you can offer these blood tests. That's where we stand at this stage. It would still be helpful to screen them with some modality, but would I place this blood test as a first or preferred line options? Not as of now. And we'll see that for their data in my uh slides in a little bit. So now, CT colonography, also known as virtual colonoscopy, is also one of the options that you can use in select group of patients. So it uses just a CAT scan, but patients do have to drink prep before they undergo colonoscopy. And the benefits are there's no need for sedation, so they drink some laxative, and the amount of laxative they drink is not as much as they have to do for a normal uh colonoscopy, so it's a much smaller. And can we do a non-bowel prep CT colonography? I've seen some studies, so that maybe in the future, they're able to separate out um uh the densities of stool from the polyp. So that will be promising. Uh, when patients go for a CT scan, even though they're unsedated, they do have a small rectal tube placed for insuffalation uh of the colon, and, uh, it's a very quick scan for less than a minute and um the caveats are there. There is some risk of radiation exposure with repeated studies, uh, cost wise, definitely more expensive than various other tests available. And, um, the, the other caveat is what do we do about finding incidentalomas like finding. Um, some, you know, renal findings, some splenic findings, some small hepatic cyst, hemangioma, how could that add to the burden, uh, of further testing and of course, patient anxiety. And CD colonographies can miss small flat, uh, small polyps or flat polyps, which, you know, here you can see in the image that how they create a 3D image and if you can see here a tiny popping, a tiny polyp that is seen, if this was a very flat sci serrated adenoma, there's a high chance that could be missed by this screening test. So when do I use CT colonography in my practice in patients who are very high risk for uh undergoing sedation? For example, if a patient who has to go is a, you know, 50 year old person, never had a screening, and they have to undergo a heart transplant or lung transplant, kidney transplant. They need to be screened before their transplant surgery, so CT colonography is a great option for those individuals who doesn't need sedation and pretty good enough to rule out any colorectal cancer or large polyp, which is the main goal for them before surgery. So, what do we do? Uh, we do a CT colonography and what do you do with the findings? We do have a statement from the latest NCCN guidelines published 2025 that if you do a CT colonography, And you find polyps, 6 to 9 millimeter, if they're small, 1 to 2 polyps, uh, then, you know, you can do a colonoscopy within 6, within 9 months, or you can just opt to repeat a CT colonography in 3 years for them. If they have multiple small polyps, then colonoscopy should be done. Or if they have a large polyp, 10 millimeter or more, then they should be offered a colonoscopy when safe. And if a CT colonography is normal and patient opts in to do CT colonography again, it should be repeated in 5 years. Another testing, uh, option, colorectal cancer screening option to us is a capsule colonoscopy, not, uh, one of the top tier tests. It's not available at UCSF. We don't offer it to patients, um, uh, but what it includes is it's uh approved by FDA for use in patients who have had an incomplete colonoscopy. So for example, you know, patients has a very tortuous colon, they attempted a colonoscopy, couldn't go through that, uh, would be one scenario could be considered. And for capsule colonoscopy, um, um, you know, patients who are not a candidate for sedation could be an option, and it's, um, it is, you know, not approved as a first line for average risk screening for your patient when you see them to consult for screening. So there are only certain scenarios it should be considered, and as I said, you know, very few centers offer it at this time. And here you can see that um uh you really need a good prep, uh, otherwise you'll miss these lesions. Unlike colonoscopy, where we have ability to, to, you know, uh uh do some water irrigation, clean certain areas, and phalate the colon to see flat lesions, this capsule colonoscopy will not have those advantages. So the prep has to be really good for this to be meaningful. And it should be repeated every 5 years, when done. An old fashioned test shouldn't be done, uh, is ovarian enema. No one should be doing this anymore, uh, now that we have a lot better, uh, you know, screening, uh, options available. I just want to take a second that, you know, digital rectal exam. In the virtual world we live in, we have fewer contact with patients. I personally have come across a few patients who presented with blood in the stool and were referred for colonoscopy, the whole, whole process from the time to referral. To getting insurance approval, to getting colonoscopy could be several months. And when you do colonoscopy, you do find a very distal rectal lesion that was easily palpable on your digital rectal exam. So, if we can do that um uh for patients who present to you with blood in stool, please consider doing digital rectal exam, and a palpable mass at that time would help you triage that patient for a more expedited colonoscopy and early detection. There was a study showing that 46% of patients who presented to their providers with blood in stool did not recall having a digital digital rectal exam. And um, so it's a low hanging fruit in symptomatic patients. Again, they shouldn't be used as a routine screening in average risk asymptomatic individuals. So little caveats for the non-invasive test, the blood test, the stool test, um, uh, you know, uh, CT colonographies, when you discuss these options with your patient, it's, it's really important that you tell them that if any of those tests will be positive, they need a colonoscopy. And, uh, and these tests need to be repeated periodically. Like a fitness should repeat once a year. Patients shouldn't go home thinking that they do one fit test and they are good for 10 years, uh, which we do see that in practice, patient doing one fit test, not repeating for a couple of years. Um, and similarly, Cologuard, Colosan, you know, shield, or um the simple show, the blood test, all of those, they do need to be repeated every 3 years. Um, uh, so it's, these are not one-time tests. And also it's important that these stool tests, blood tests, um, are only for average risk screening population. So if you have a person, you know, they have had polyps before and they wanna come do, uh, you know, stool test today, uh, that's not the right option for them. If past history of polyp is considered above average risk and should undergo colonoscopy. Similarly, if they have family members, especially first degree family members with colorectal cancer, they should be offered a colonoscopy. Past history of childhood cancer resulting in exposure to chemo, radiation, and cystic fibrosis, or history of various hereditary cancer syndromes, those individuals as of now should undergo colonoscopy. I must mention that there's a Cologuard stool test going on. A study is undergoing, uh, for Lynch syndrome. We'll have to see the data before we incorporate that in higher risk patients. As of now, colonoscopy is a test for average, above average risk individuals. So this is an important slide for us to look at, you know, now we have so many tests, how do they compare? So, um, here you can see, uh, there are column one, here you see that colonoscopy, the colorectal cancer sensitivity for colonoscopy is about 96%. And advanced precursor lesions, so we're talking about advanced adenoma, 1 centimeter or more high-grade lesions, it's pretty sensitive, up to 95%. And um uh here, if you see that, um, for fit test, you know, the sensitivity goes down to 74% and multi-target stool DNA Cologuard testing, the sensitivity is pretty good, 92%. But the caveat is here, their sensitivity for advanced uh um polyps is only 42%. It's a significant reduction in their ability to detect even advanced polyp. We're not talking about small polyps. Similarly, you know, um, uh, Colosense has pretty similar sensitivity for colorectal cancer detection, but for advanced polyp detection is only 46%. If you look at shield blood tests and the phenome-based simple screen blood tests, they are pretty good for detecting advanced stage colorectal cancer, like stage 2 and above. They do poorly even for detecting stage 1 colorectal cancer. So, so only 55% sensitivity of shield and phenome uh simple screen for detecting stage one colorectal cancer. And their sensitivity is very poor when it comes to detecting advanced polyps, so they're close to, you know, 12-13%. So it's really important for us to share this data with our patients when we are talking about various screening options. What is patient's goal? If patient's goal is colon cancer prevention and detection of advanced polyps as well, I wouldn't offer them a, a blood test at all. And similarly, the patient's goal is for, you know, uh, one-stop shopping for getting the screening, and if there are polyps seen that can be removed as well, and then they don't need to think about their colorectal cancer screening for various years, for 5 to 10 years, then colonoscopy is the gold standard. If patients are opposed to sedation and the cost and risk factor for sedation, then stool test is a wonderful idea with fittest, Cologuard, and now with Colosense. All right. So, as we discussed the sensitivity and specificity, it's also important for us to uh put on a lens to see how does it matter in long term. So we don't have studies for any of these tests comparing head to head and how it affects, you know, uh, long term, but we do have various, uh, modeling studies and. This is again an important slide that in a recent modeling data from a lot of them and group showed that if your patients do a fit test every year versus a Cologuard every 3 years and a shield test every 3 years and colonoscopy every 10 years. So if you compare these tests in these modeling studies, they saw that reduction in risk of developing colorectal cancer. Um, compared to no screening here you can see was 57 to 80% um in patients who underwent colonoscopy, but this was very, very low, uh, for patients who underwent blood tests, and we had about, you know, 40 to 70% for fit test and Cologuard test. So one is the the risk of developing colorectal cancer, but also if we look at in these modeling studies, reduction in risk of dying from colorectal cancer, here you can see the data was a lot more, you know, uh, robust for colonoscopy, a fit test, and a Cologuard, uh, stool-based testing, uh, but these data were again very limited for patients who underwent, uh, you know, who. We modeled as getting guard, you know, uh uh cell-free DNA shield testing. So again, this is important for us to keep in mind as we counsel patients for various screening modalities. So now I shared with you various tests, and if your question is, what is the best test, well, the answer is still the same. The best test is, is the test that your patient will get done. And we do have some guidance from various societies for a tier one test, tier 2 test, and not recommended tests. So, ACD's Multi-society Task Force, uh, last recommendation in their tier one is colonoscopy every 10 years or fit test every year, uh, were listed as tier one test. They included flexible sigmoidoscopy, multi-targeted stool DNA, which is a Cologuard test, and a CT colonography, uh, in tier 2 test, and capsule colonoscopy was also a tier 2 test. They did not recommend septin9 blood tests, which we discussed already, and these guidelines came, uh, uh, before the blood test became commercial. So we did discuss how they should be placed in the algorithm. Similarly, what do we have statements from other like what does USBSTF uh uh say? It's, you know, it, it says that no empirical data demonstrate that any particular strategy works, provides good. You know, uh, a lot better benefit than others, so they do suggest USPSTF does have WA FOBT annual, annual fit test, Cologuard every 1 to 3 years, a CT colonography, um, every 5 years, colonoscopy every 10 years, and flexing every 5 to 10 years combined with annual fit as one of the screening options, uh, listed, um, in their last. Guidelines. So now, moving on to um high-risk patients, and um here we can see that I, I discussed briefly that patients with cystic fibrosis have higher than average risk, and we should be offering them colon cancer screening. At a younger age. So if they haven't had any organ transplant starting age 40 and repeating every 5 years, and if they have had organ transplant or they have adenoma found, the colonoscopy should be done at a younger age or more frequently. Similarly, patients who have had, uh, you know, history of childhood or adolescent and young adult colorectal cancer, these are risk factors for colorectal cancer, and these individuals should be offered colonoscopy, for example, you know, if they have had radiation therapy. Then start colonoscopy at age 30 and repeat every 5 years. And if they did not receive any chemotherapy or radiation, then average risk screening could be considered for them and starting at age 45. So taking this history from your patient at the time of screening counseling is important. All right, so we discussed that most societies agree on starting colonoscopy at age 45, and that's what, you know, I recommend as well. So when do you stop it? So generally, the short answer is, you know, never offer a colonoscopy or even colon cancer screening to a person who has life expectancy less than 10 years. Um, start at age 75, sorry, start at age 45 and stop around, uh, stop at age 75. In age range 75 to 85, we do offer screening, but that is case by case, so it should be offered to a patient who never had any screening. You see them first time and they are like, you know, 78 year old, 80-year old, they are still in good health. I think it's very reasonable to offer them one-time screening for colorectal cancer. And if patients are in very good health, you know, question about surveillance colonoscopy as well. So between 75 to 85, um, we do make case by case decision for patients in great health who are very eager to go through, and we certainly can offer. After age 85, we do make a hard cutoff, do not offer a colorectal cancer screening or surveillance. So what are the polyp surveillance guidelines? So we do, let's say we do colonoscopy, we find polyps, and these guidelines have evolved. So these are the latest one in 2020. The major shift was for patients with one small 1 to 2 small adenoma, we, we used to offer five-year colonoscopy that was changed to 7 to 10 years and important to review with your patients who may have had older recommendations. So if they have 1 to 2 small adenoma uh less than 10 millimeter, they should undergo in 7 to 10 years, and here it's listed again, if they have 1 to 2 small sessile serrated polyps less than 10 millimeters, they should undergo colonoscopy in 5 to 10 years. And the clinical implication for these guidelines are. Uh, occasionally, patients will get worried when it's a 5-year mark that, you know, if they have some other medical issues going on as well, um, it's important to share the range, uh, with them and plan accordingly to offer colonoscopy at the right time. And here you can see how the guidelines recommend more frequent colonoscopy, 3 to 5 years, or 3 years or even 1 year for individuals with larger polyps or higher number of polyps. Similarly, a common question I get asked is a patient had a baseline colonoscopy finding and then they had um a follow-up colonoscopy, and when should their next colonoscopy uh be so I wouldn't read through every single line here, but a great resource for you to refer for patients who had, for example, you know, a baseline. Colonoscopy showing 1 to 2 small tubular adenoma, they get a repeat colonoscopy which shows a which is normal, you know, that patient, if they have no family history, can actually go back to 10 year, uh, screening recommendations. Uh, in the past, you know, we used to offer more often, uh, but now we have seen that these patients can very. Uh, safely be placed in 10 year follow up and similarly, uh, here you can see that patients who had even multiple polyps and if they have normal colonoscopies can be placed in a 10 year cycle and the ranges are listed here for other polyps sizes and number. All right, so now moving on to colonoscopy referral checklist, which I was asked to review. So when you, let's say if you discuss all the available colon cancer screening options with your patient, or if your patient is above average, you refer straight for colonoscopy, and certain things, it's very helpful if you discuss that they are willing to drink colonoscopy prep, and, you know, they must have a right to take home after sedation. And uh if they don't have a ride, there are some medical transportation options uh available which most patients have to pay. They need to have a discussion beforehand. Uh, always helpful to have last colonoscopy report for us as endoscopists to make recommendations for the future colonoscopy because we do account for what was seen before, um. And then also listing if patients are safe for sedation, you know, if they have cardiopulmonary risk factors, sleep apnea, a commonly missed one is frequent marijuana use, um, that does help us for direct patients scheduling for colonoscopy if we decide if they should be scheduled with moderate sedation that involves using fentanyl Versed for at UCSF versus we should be looking at propofol for that individual. So a common miss scenario is someone taking marijuana frequently is scheduled for, you know, average risk colonoscopy, and marijuana was not listed in the referral. If you scheduled with fentanyl was said, uh, it's really hard to sedate those individuals even with the highest safely allowed dose and can result in incomplete procedure. Those patients do really well with uh propofol that needs to be scheduled with anesthesiologist in advance. And we already discussed that if your patient is very high risk for sedation, like about to undergo, you know, transplant, um, yeah, then, uh, the risk of anesthesia for them is, is above average. You just, you know, they don't need to be referred for a colonoscopy. You can do a CT colonography, and many of those will have a small polyp or normal. They do not need a follow-up colonoscopy. We're always happy to help if they have, you know, larger findings on those CT colo which are done unsedated. And a CT colonography referral can be placed directly to radiology. It does not need to go through a gastroenterologist. Uh, colonoscopy preps. So, uh, always good to remind your patients that, you know, we do have several colonoscopy prep options available now, unlike before. So patients generally thought colonoscopy means drinking a whole large gallon, uh, but fortunately, we have a lot, you know, the size of the prep boxes keep on getting smaller and smaller. Uh, so, uh, we do. You have, you know, various are listed here, um, and we have movie prep, prep topic, rep, Suablen, and others as well, and here, uh, um, we can see that certain preps are actually tablet-based and patients who have difficulty drinking larger liquids could also choose these and we try to reserve. These low volume preps, uh, we try to, you know, uh, patients who have kidney issues, cardiac issues, we like to triage them still back to politely, but for most of the average risk individuals, we have lots of options. Generally, it depends on insurance contracting for which patient will be able to get which prep, and so we do have to work it out with them, but most of the patients in my experience are able to get low volume prep, uh. Uh, recently, which has improved the experience quite a bit. Uh, and I'm sorry, it's lunchtime. If you are eating lunch, uh, I just have to show the importance of, you know, bowel prep, and, um, uh, and please counsel your patients that they should follow through bowel prep if they are direct scheduling that, uh, uh, quality of colonoscopy depends a lot on the quality of bowel prep. At UCSF we do have endo.UCSF.edu. We have listed patient instructions. These images are from there to guide them what is the target bowel prep they are looking for and uh also the bowel prep instructions are listed there for patients and you to refer for any questions. A few tips and tricks for colonoscopy. It's about 20 to 30 minutes plus minus procedure. Patients spend about 3 hours in the hospital, you know, they, uh, we do ask them no driving for 24 hours if they have sedation, which is most of the patients, and, um, um. Very rarely we can offer sedated colonoscopy, which is just, you know, if patients have a strong preference, um, so I have done a few, but it's a rare patient requested only shouldn't be uh uh routine, uh, can be a very uncomfortable procedure, and patients have to take split dosing. So the second half of the prep is taken 4 to 6 hours before the procedure. And some data that even same-day prep can be taken early in the morning for a late afternoon procedure. So many modifications have happened over the years. Um, so if a patient doesn't like to wake up, you know, middle of the night, they shouldn't schedule 7:00 a.m. colonoscopy. They may be fine doing scheduling at 4:00 p.m. in the afternoon, and then they can wake up at a reasonable hour, 6 hours before that and drink the prep. Uh, so I do discuss these with my patient. And uh risk of delayed bleeding is, you know, 2 to 4 weeks after um a complex polypectomy if what uh uh EMR is done for these patients. And I've started discussing this with my patients, um, in, in, in last, you know, uh, a couple of years, I have done colonoscopy in individuals if they had. An example will be someone had a colonoscopy in the East Coast for a routine screening purpose. They had a large polyp EMR and then they fly two days later here for a business conference, and they have delayed bleeding, uh, a week later, and they have to have a colonoscopy here. Um, so, generally, we don't restrict patients from travel and all, but for a patient who is going to have, you know, known high-risk polyp to be taken, good to have this discussion, uh, for just in case rare scenarios. Diet before colonoscopy. So in the past, you know, we gave clear liquid diet before colonoscopy. Many patients felt that's too much dietary changes. We have uh advances in that as well that patients can eat low residue diet the day before colonoscopy when they prep. And in that low residue diet, we have seen that the quality of prep. Actually, in some studies is shown that patients actually may do better if they are eating solid low residue diet the day before because it stimulates colonic movement and patients tolerate the prep better if they're not starving and hungry, they're more likely to finish the whole gallon uh versus if they were starved and hypoglycemic. So here is a list, you know, patients with low residue food they can eat the day before includes, you know. Samples are eggs, uh, yogurt, and, you know, white bread, and the list goes on, and this definitely can improve patient experience. Certain images to show how polyps can, you know, range in shapes and shapes and sizes and different tools that we use from biopsy forceps to snare for colonoscopy, and, um, you know, the techniques are variable from EMR to um uh various polypectomy, EST techniques, depending on the size and shapes of the polyp. So switching gear to family history of colon cancer, so when you refer someone for colon cancer screening, as we discussed, if they have family history, they especially first degree, they should consider colonoscopy, and we have seen in the studies that risk of colon cancer in a patient goes up as uh as um as the number of relatives with colon cancer goes up as well. So someone with first degree relative with colorectal cancer risk, you know, uh, uh, is, is about twofold more than someone who doesn't have, and if their relative was younger, their risk is higher, and if they have more than one relative with colorectal cancer, the risk for patient, uh, is, you know, uh, goes up further. So having a history of how many individuals they have in the family can help you triage their risk. So how do we do? So we discussed that, we do colonoscopy for those individuals with colon cancer in their family, and so what guidance do we have? Here is NCCN guideline for you if anyone with first degree relative with colorectal cancer at any age. So first degree is mom, dad, brothers, sisters, and, you know, siblings, uh, siblings and uh children. So, if they have any of these individuals with colorectal cancer, then you should offer colonoscopy to your patients starting age 40 and uh or 10 years before the earliest cancer diagnosis, whichever is first and repeated every 5 years. And what about their 2nd degree and 3rd degree relatives, like, you know, uncles, aunts, grandparents, great uncles. As of now, we don't have clear data for them and for, for now, unless they have numerous, you know, 2nd or 3rd degree relatives. Uh, if they have one, let's say their grandfather had colorectal cancer, as of now, we offer colonoscopy starting at age 45 and repeat every 10 years like everyone in those individuals, um, uh, until we see further data. Uh, one more point here I would like to make that we know about colon cancer, we're good about it in family history, but what about advanced adenoma? So we have seen that, let's say if I see a person, they have, you know, 2 centimeter uh tubular adenoma, tubularulous adenoma, which is not a cancer, uh, they're first degree relatives, so their siblings, parents do have increased risk just like a colorectal cancer. Cancer and even then they should consider their family members' colonoscopy starting at age 40 and repeat every 5 to 10 years and uh this should also be discussed with your patients at the time of colonoscopy. All right, so now, uh, you know, having a hat off my as a Lynch syndrome, uh, provider here at UCSF, I must have to address when should you think about genetic testing in your patients. So if you see a person, you refer them for, you know, trying to refer for colonoscopy, they say they have family members for colon cancer. Commonly, uh, we have seen in multiple studies that family history intake is. Limited just because you have so much to do, um, so the system needs to improve, uh, but, uh, always a good idea to take a quick family history of how many who had colorectal cancer and even non-poorectal cancer and what was the age of diagnosis and if patients, for example, you can use these NCCN criteria to make a referral for genetic testing. So if a patient or a first degree relative were diagnosed with a colorectal or endometrial cancer at age 50, they are high risk for Lynch syndrome, and you should offer those individuals for germline genetic testing. Uh, UCSF does have in-house germline genetic testing panel with appropriate counseling. It can be ordered by any provider as well. And patients with, you know, here I wouldn't read all of these guidelines, but here you can say that we always think about young age colorectal cancer as a red flag for um uh referral for genetic testing, but here you can see that patients of um a first degree relative, if they had uh uh rectal cancer or endometrial cancer, and if they have other lynch. Related Lynch syndrome related cancers and even if they were multiple, if they were multiple individuals and even if they were diagnosed at a later age, so if there are at least 3 of them are diagnosed with various, you know, even if they are 1st or 2nd degree relatives and diagnosed with Lynch related cancer even at older age, that's a red flag for Lynch syndrome in those patients, and they should be referred for mline genetic testing. What is the other way you can, you know, uh, uh, refer your patient for genetic testing. So at UCSF we built this UCSF hereditary cancer risk calculator. It can be seen on this link or you can go to UCSF Lynch syndrome Center website and uh access this calculator there. It's a red cap-based calculator which we designed for very patient friendly language. It asks you a few simple questions, you know, who had colon cancer. What was the age of diagnosis, and it tells in the end with the back end uh logic that this patient does meet criteria for germline genetic testing for Lynch and we also built BRCA in that because that's an equally important, you know, cancer risk for individuals. And once your patient meets that, you can make a referral directly through this, that website to the, to the cancer center for discussion of genetic testing in those individuals. So Lynch syndrome is very common. 1 in 300 people in general population have that, um, and, you know, the sad news is more than 90% of these individuals are undiagnosed. So hopefully taking the family history, making the referral, we can change the needle. And important to diagnose these individuals because they need colonoscopy, you know, more frequently, every 1 to 2 years. And then there are various cancer prevention vaccine trials going on. Can we train your immune cells against the tumor associated antigen. And give you a vaccine to lower your risk of cancer formation that we participated in TriA 51 here at UCSF and there are other MOS 209 as well that patients can take the opportunity to participate if they are diagnosed. So in conclusion, in 2026, we have multiple colorectal cancer screening options available and, you know, shared decision making, uh, uh, based on, you know, what's available, what's acceptable, what's affordable, uh, so the best test is the one that your patient will follow through. And it should be offered for patients 45 to 75 years, 75 to 85 case by case, and a line about that colonoscopy and stool tests are preferred screening options in average risk individuals, and the blood tests have very poor sensitivity for advanced adenoma and stage one colorectal cancer. So as of now, blood tests should be offered only for individuals who have declined other modes of colorectal cancer screening. With that, this was my last slide, and I really appreciate everyone joining in and we'll be more than happy to answer any questions.
