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New Frontiers in Polypectomy
Best Practices in Polyp Resection, Barriers to Implementation.
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Polypectomy is a fundamental practice in colonoscopy, well known to effectively reduce colon cancer incidence and mortality. However, despite numerous advances in polyp resection techniques and technologies in recent years, studies have shown that high rates of incomplete polyp resection persist, which are responsible for 15% to 30% of interval cancers by some estimates.
Although mounting data have sparked a transition during the past decade from piecemeal cold biopsy to cold snare as the preferred method for complete resection of diminutive and small polyps, cold biopsy — and less commonly hot snare and hot biopsy — are still being practiced. Furthermore, large polyps are still often removed surgically despite the less invasive alternatives that are becoming increasingly available.
According to experts interviewed by Healio Gastroenterology, the data clearly demonstrate the superiority of currently recommended best-practices for polypectomy, namely cold snare for small and diminutive polyps and endoscopic mucosal resection (EMR) for large polyps. Although there is a trend toward increased adoption of the preferred techniques, these experts agreed that several unique obstacles continue to delay widespread implementation, particularly among community gastroenterologists.
Diminutive, Small Polyp Resection
Accumulating research indicates that cold snare polypectomy is the best method for removal of small and diminutive polyps. A recent review published in Clinical and Experimental Gastroenterology cites three studies whose findings demonstrated the superiority of cold snare vs. hot snare polypectomy, as well as results from a recent comparative study demonstrating a 93.2% histologic eradication rate with shorter procedure time using cold snare compared with 75.9% using biopsy forceps (P=.009). A recent observational study also confirmed the safety of cold techniques, with a 1.8% rate of immediate bleeding and no delayed bleeding or perforation. Even more recently, findings from a systematic review and meta-analysis presented at the American College of Gastroenterology Annual Scientific Meeting by Dany Raad, MD, of Case Western Reserve University in Cleveland, demonstrated inferiority of cold biopsy. “There is moderate quality evidence that using [cold snare or jumbo biopsy] reduces your risk of incomplete diminutive colonic polyp removal by 52% as compared to cold forceps biopsy without increasing your procedure time,” Raad said in his presentation.
Tonya Kaltenbach
Data demonstrating the superiority of cold snare for diminutive and small polyps is well established, “but it is certainly still not practiced,” Tonya Kaltenbach, MD, MS, from the Veterans Affairs Palo Alto, told Healio Gastroenterology. “Both academic and community practices are still practicing cold biopsy or, even in some cases, hot biopsy for diminutive or small polyps.”
These results are relatively recent, and so the techniques utilized by endoscopists have traditionally been widely varied. A 2004 survey of American gastroenterologists, for example, showed that for lesions 1 mm to 3 mm in size, half of those surveyed used hot or cold biopsy forceps, and for polyps 4 mm to 6 mm in size, 59% used hot snare, 15% used cold snare, 19% used cold biopsy and 21% used hot biopsy.
Use of hot biopsy for small polyps has certainly decreased in the 10 years since this survey was conducted, Kaltenbach said, due to increased risks for delayed postpolypectomy bleeding, perforation, coagulation syndrome and cauterization of the tissue that prevents pathologic interpretation associated with cautery.
“When you use cautery, the advantage, of course, is you reduce the chance of immediate bleeding, but you run the risk of delayed bleeding,” Raman Muthusamy, MD, director of interventional endoscopy in the division of digestive diseases at UCLA Health System, said in an interview. Furthermore, using cautery “can create thermal injury that can lead to full thickness injury of the colon wall, which can lead to acute or delayed perforation in a worse-case scenario. There also is the potential for irritation of the outer lining of the colon wall, which can result in postpolypectomy syndrome,” wherein patients can experience sharp abdominal pain that can mimic a perforation and therefore lead to an unnecessary surgery, he said. “Generally, resection of small polyps using cautery is overkill, and the risks are greater than the benefits.”
Raman Muthusamy
Endoscopists may once have been hesitant to perform cold snare because they were afraid of bleeding, “but that has basically been refuted,” Kaltenbach said. “Several studies on immediate and delayed postpolypectomy bleeding show nominal rates of bleeding when you use cold snare. So the safety of cold snare has been shown, and now the efficacy of cold snare compared to cold forceps has been shown, so this shouldn’t be controversial. The controversy now is more of a practical issue — that people are still practicing the technique (forceps removal) that they learned when they were first trained.”
Adoption of any new technique in the field of endoscopy, Kaltenbach said, “is delayed because mechanisms to learn outside of fellowship are few and far between, especially technical learning.” For technical skills, she said, learning opportunities outside of hands-on courses or shadowing and being proctored are scarce. “Even though the data can be clear, adoption is often slow, delayed, sometimes met with resistance because the opportunities to learn it are difficult.”
Another potential barrier to adoption are the short-term finances of snare polypectomy, but these even out in the long term, Kaltenbach said. Although the snare itself may be slightly more expensive than biopsy forceps, snaring has a slightly higher reimbursement rate. Furthermore, when considering the higher rates of incomplete resection associated with cold biopsy, which could potentially lead to increased rates of interval cancers, “there is no debate that cold snare would be more cost effective.”
“It may even be a more time-efficient technique,” Muthusamy said, which has obvious financial implications. “If you have to pass a forceps three or four times to adequately remove a polyp as opposed to just removing it en bloc with a cold snare, and you have three or four polyps per colon, over the course of a day that could add up to significant differences in procedure time, which could potentially turn into significant money over time.”
Large, flat colon polyp at the splenic flexure.
Image: Christopher J. DiMaio, MD
Large Polyp Resection
According to the experts interviewed by Healio Gastroenterology, large polyps are too often removed by unnecessarily invasive surgery due to a lack of training among community practitioners in less invasive alternative techniques.
“EMR is the preferred technique for removal of large polyps,” Kaltenbach said, adding that many studies have now demonstrated that outcomes have low postpolypectomy bleeds, high complete resection and curative resection. One such study demonstrated 95% success with piecemeal EMR in the removal of difficult sessile polyps larger than 20 mm; surgery was subsequently avoided in 90% of cases, and morbidity, complications and costs were reduced as well.
“Most important is that EMR is a curative alternative to surgery,” Kaltenbach said. In several studies, the average polyp sent to surgery was 2 cm in size and benign, which she characterized as “unfortunate … when there are endoscopic techniques that are shown to be curative for such a polyp.”
Christopher J. DiMaio, MD, director of therapeutic endoscopy in the Mount Sinai Endoscopy Center at The Mount Sinai Hospital, cited a similar statistic, having “recently learned that more colon surgeries are being performed for benign neoplastic lesions than for malignant ones — which is unacceptable in my mind. Our goal is always to prevent or minimize the need for surgical resection … and there is a huge disconnect between what happens in the community and at tertiary centers.”
In the community practice where the majority of large colon polyps are found, DiMaio said doctors often send their patients for surgery, and some surgeons “will remove one-third to one-half of the colon in order to take the polyp out.” Tertiary centers, conversely, are able to “safely, easily and effectively remove those polyps with standard endoscopic techniques.”
Complete resection after colonic EMR.
Image: Christopher J. DiMaio, MD
Endoscopic removal of flat lesion using EMR with dynamic injection. (A) A flat lesion is detected between the folds. (B) The flat lesion is raised to form a bleb, using dynamic submucosal injection with a mixture of saline and diluted indigo carmine. (C) The snare can then easily capture the lesion for complete removal.
Image: Tonya Kaltenbach, MD, MS
EMR is particularly important for nonpolypoid colorectal lesions, according to Kaltenbach, as “it is difficult to capture a flat polyp in a snare without also capturing the muscle.” In her paper published in the July 2010 issue of Gastrointestinal Endoscopy Clinics of North America, Kaltenbach details the inject-and-cut colorectal EMR procedure, which entails raising “the diseased mucosa away from the muscularis propria by the creation of a submucosal bleb using saline solution.” Afterward, she said, “we are able to put the lasso around it and snare it, so it makes it something that could be challenging very simple to remove.”
Still, despite the demonstrated efficacy of inject-and-cut EMR, “the majority of nonpolypoid lesions are typically referred for surgery due to a variety of reasons including insufficient technical skills, perceived high complication risk, increased use of endoscopy resources and time, and inadequate reimbursement,” Kaltenbach wrote in the paper.
“EMR is attractive,” she said, “because you can do curative resection of benign polyps that are large and avoid having surgical resection, so it is minimally invasive, organ sparing and more cost effective. It should be the absolute standard of care — the first-line therapy for benign polyps in the colon.”
Endoscopic Submucosal Dissection
Piecemeal EMR for most colonic polyps is adequate, Kaltenbach said, but a very small number of polyps, namely nonlifting polyps, those with the characteristics of early submucosal invasion, or those detected in patients with extensive scarring from inflammatory bowel disease, endoscopic submucosal dissection (ESD), may be indicated.
“ESD is a technique that was pioneered in Asia as a way to remove early gastric cancers,” DiMaio said. The traditional approach for surgically removing precancerous lesions in the stomach, “is often a radical total gastrectomy or subtotal gastrectomy, so they have adopted and pioneered basically what amounts to endoscopic surgery, where they elegantly dissect out the entire lesion in one piece.” The advantages, he said, include the ability to dissect “extremely large areas that could not be done with one snare, and most importantly, it is removed in one piece so the pathologist can see without any question where the lateral and deep margins are to confirm if it is a true complete resection.”
According to DiMaio, Asia is about 2 decades ahead of the United States in terms of how well ESD is performed. “With their experience, they have adopted it to the esophagus, the rectum, and it is starting to be done in the colon, as well.”
Because gastric cancer is not nearly as common a malignancy in the United States, there has not been as urgent a need for screening programs or ESD techniques in Western societies, he said. “That being said, as everyone wants to adopt new techniques and incorporate them into their practices, there is a need for such techniques to remove precancerous or cancerous lesions of the esophagus, stomach, small bowel, colon and rectum.”
Besides the limited indications for ESD based on population-specific needs, the main barrier to implementation in the United States, DiMaio said, is the exceptional level of skill required due to its high risk for surgical grade bleeding or perforations. To be proficient, he said, a practitioner should be adept at EMR, controlling bleeding endoscopically, and recognizing and controlling a perforation. Furthermore, due to the learning curve, he said, ESD can take up to 4 or more hours in the United States, compared with a routine 60 minutes in Asia.
Muthusamy agrees that the lengthy procedure time of ESD, compounded by its similar reimbursement to EMR in the United States, is a major barrier to widespread adoption. “Given the time-consuming nature, the increased potential for adverse events, and the really insignificant change in reimbursement,” most endoscopists feel it is impractical to pursue the extensive training required to practice ESD, he said.
Training for ESD is indeed extensive; according to DiMaio, the current expert opinion on training entails self-guided cognitive learning about the diseases and equipment, watching videos, hands-on training in both ex vivo and live animal models, then observation of procedures performed by experts. The majority of those training opportunities are in Asia, he said, but are increasing in Europe and the United States.
Because of the enormous commitment, and the reality of American practitioners having to fund their own training oversees, DiMaio said awareness education about ESD and other advanced endoscopic techniques among community practitioners is most important. “Community practitioners need to understand that, at specialty centers, advanced endoscopists are well equipped to safely and effectively remove large lesions, whether they be benign or early cancer, and they have a whole range of techniques and tools at their disposal, all in the name of preventing the patient from requiring surgical resection.”
There is definitely an interest in learning ESD, Kaltenbach said, but based on her experience in the courses she has taught, “in the United States, the practitioners are interested in learning EMR. Indeed, it will be a victory for patients and the health care system at large if we teach gastroenterologists broadly to do EMR. The focus from the societies and educators should be on that because the majority of large polyps can be effectively removed with EMR, but currently many of them are sent to surgeons.”
Advances on the Horizon
“The fact of the matter is colonoscopy is under some scrutiny right now, in terms of right-sided colon polyps and its impact on reducing right-sided colon cancers,” Muthusamy said. “We have a lot of deep assessment of colonoscopy at this point. It has been the unquestioned king of colon cancer screening/surveillance for some time, and to some degree we haven’t really asked hard questions about performance improvement. We are now seeing an optimization of the whole process.”
According to DiMaio, this optimization comes along with some interesting innovations. “Some enterprising endoscopists are starting to learn to dissect their way into the deeper levels of the GI tract wall in order to remove benign or premalignant tumors arising from the muscularis propria — something called endoscopic full-thickness resection.” Others, he said, are doing procedures that are “basically no different than a laparoscopic surgery, and they are resecting sizeable benign tumors that would otherwise need surgical resection. The key to being able to do this is that we have better ways of closing these holes we create,” such as the novel over-the-scope clipping system or endoscopic suturing devices.
“The over-the-scope clipping system has been a major advance in the endoscopic tools that we have available,” Kaltenbach said, which “allows for larger and full-thickness closures. I think that such devices are encouraging, but in terms of tools for removal of polyps, in general, there is no magic answer. Learning the technical skill with the currently available and effective tools is still the key step.” – by Adam Leitenberger
References:
Hewett DG. Gastroenterol Clin North Am. 2013;42:443-458.
Kaltenbach T. Gastrointest Endoscopy Clin N Am. 2013;23:137-152.
Kaltenbach T. Gastrointest Endoscopy Clin N Am. 2010;20:503-514.
Tripathi P. Abstract 24. Presented at: ACG Annual Scientific Meeting; Oct. 20-22, 2014; Philadelphia.
For more information:
Tonya Kaltenbach, MD, MS, can be reached at endoresection@me.com.
Raman Muthusamy, MD, can be reached at raman@mednet.ucla.edu.
Disclosures: Kaltenbach is a consultant and has received research funding from Olympus America Inc. Muthusamy is a consultant and has received research support from Boston Scientific Corporation and Covidien GI Solutions, and has received research funding from Cook Medical. DiMaio reports no relevant financial disclosures.