colonoscopy on the ASGE SUTAB tip of the week. This is a patient that was referred for resection of a 12 to 13 millimeter sessile lesion in the distal transverse colon. You saw the tattoo. And now we've gone to the cecum. We always go to the cecum in patients referred for resection of a benign polyp to make sure that there isn't other important synchronous disease in the colon. You can see why this lesion has the morphology of cancer. There's the nice three pattern disruption of the vascular pattern. You can see the white color of nice three or KUDO5. The lesion is excavated. But one of the first lessons that we want to present with this case is that we're not going to immediately biopsy that lesion. Now the lesion needs to be biopsied. We need to demonstrate by pathology that it's got cancer, but we're going to put it off first and we're gonna clear the colon. So principle number one, when a patient is referred for a resection of a large sessile lesion, we always want to look at the entire colon. I don't always try to clear it in detail. In this patient, because they're gonna need a right hemicolectomy, I am gonna clear it in some detail. We're doing an EMR here on a lesion that's in the proximal transverse colon, maybe 20 millimeters in size that we're removing by piecemeal EMR with electrocautery. Now presumably the referring doctor did not see this lesion. We've used electrocautery. We're gonna need to do sneer tip soft coag and then because it's proximal to the splenic flexure, we are going to clip close it to prevent bleeding and now we're just a few centimeters more distally and here's a second lesion, a flat lesion. Also again, presumably not seen by the referring doctor, but this case points out the very high prevalence of synchronous disease in patients who are referred for sessile lesions. In our study of more than 700 patients with a non-pedunculated lesion 20 millimeters or larger, we found that the average number of additional adenomas detected at our colonoscopy was four. 40% of the lesions had an additional advanced adenoma other than the one that they were referred for. 20% of them had a second lesion, actually 20 millimeters or larger in size. Here is the defect after STSC and clip closure of a second lesion and now we're removing the lesion the patient was referred for and because it's a bit smaller, we're actually just removing it without EMR using hot sneer cautery. You can see the tattoo had spread under the lesion. This patient also had an additional seven small adenomas under a centimeter in size. Now we're down in the rectum and we're doing retroflexion. I was saying that in our study, we talked about the high prevalence of additional adenomas. Almost 1% of the patients had cancer in a lesion separate from the one that they were referred for. So important principles we've seen, check the whole colon, look for synchronous disease, even the possibility of a synchronous cancer. If we find a cancer as we did in this case, we've put off the biopsy and you can see we're now headed back to the cecum, we're passing EMR sites, we're passing the sites where small polyps were removed and as the final step in the procedure, we're then going to biopsy the small cancer in the cecum. Now why delay it? It's because a study published in Gastro last year that came from the Dutch National Pathology Registry, looking at a several year period of cases of metacronous colon cancer. These were cancers that appeared six months to three and a half years after an initial cancer and of 22 cancers that met that definition, five of them occurred at the sites of biopsies or polypectomies, suggesting that they resulted from intraluminal tumor seeding at those sites and for three of those cancers, they had tissue and they showed that the molecular signature was identical to the original tumor. They also showed that when you biopsy cancers, that the channels of the scope as well as the instruments that you pass through it become contaminated with tumor cells that stay viable, even if you try to wash the channels out, they will stay viable. So now as the very last step of the procedure, we are biopsying this cancer. Principles demonstrated in this case. First, if you're in a referral center, don't stop on the way in to address the lesion the patient was referred for, go to the cecum, find out if there are synchronous lesions that could affect your approach to the lesion that the patient was referred for. Second, be aware that patients with large non-pedunculated lesions have a very high prevalence of synchronous disease. Occasionally, there is cancer in a lesion other than the one the patient was referred for. So anytime we encounter larger lesions, be aware of this high risk of synchronous disease, take responsibility for clearing the colon of that synchronous disease. Finally, anytime we encounter cancer in the colon, the last step of the procedure should be biopsy of the cancer. And this is because of this phenomenon of tumor seeding, intraluminal tumor seeding that we've been alerted to by recent studies that I've listed here. We need to know a lot more about this, but we can at least take this initial step of reducing this risk by making biopsy of the cancer the last step of the colonoscopy. Thanks for joining me today, and see you next week on the ASGE SuTab tip of the week. Thank you.

colonoscopy

ASGE SuTab tip of the week

sessile lesion

electrocautery

snare cautery