From the Journals

VIDEO: Large distal nongranular colorectal polyps were most likely to contain occult invasive cancers

Publish date: August 1, 2017
By
Amy Karon
MDedge News

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Assessment is the next step after detection

In recent years, substantial efforts have been made to improve both colonoscopy preparation and endoscopic image quality to achieve improved polyp detection. In addition, while large, complex colon polyps (typically greater than 20 mm in size) previously were often referred for surgical resection, improved polyp resection techniques and equipment have led to the ability to remove many such lesions in a piecemeal fashion or en bloc via endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD).

Dr. V. Raman Muthusamy

However, while much attention has deservedly been focused on improving our ability to detect and resect colon polyps, efforts focusing on optimizing the inspection and characterization of large colorectal polyps or laterally spreading lesions to determine resectability have received less attention. This intermediate step between detection and resection is critical, as it can determine whether endoscopic resection is likely to be curative or if surgery will be necessary. Overt visual features that suggest invasive (into the submucosa or deeper) cancer that would warrant surgery include the Kudo V pit pattern and the presence of depressed or excavated lesions (Paris classification 0-IIc and III). However, little information regarding predictors of submucosal invasive cancer exists for patients without endoscopic criteria for invasion. In this study of 2,277 lesions in 2,106 patients conducted over 8 years at eight Australian centers, Dr. Burgess and colleagues aimed to answer this question and identified four key features associated with “covert” submucosal invasive cancer in these polyps. They include a rectosigmoid location, Paris classification, surface morphology (granular vs. nongranular), and increasing size.

The authors are to be congratulated for their meticulous and sustained efforts in acquiring and analyzing this data. These results provide endoscopists with some important, practical, and entirely visual criteria to assess upon identification of large colon polyps that can aid in determining which type of endoscopy therapy, if any, to embark upon. Avoiding EMR when there is a reasonably high probability of invasive disease will allow for choosing a more appropriate technique such as ESD (which is becoming increasingly available in the West) or surgery. In addition, patients can avoid the unnecessary EMR-related risks of bleeding and perforation when this technique is likely to result in an inadequate resection. Future work should assess whether this information can be widely adopted and utilized to achieve similar predictive accuracy in nonexpert settings.

V. Raman Muthusamy, MD, is director, interventional and general endoscopy, clinical professor of medicine, digestive diseases/gastroenterology, University of California, Los Angeles School of Medicine. He is a consultant for Medtronic and Boston Scientific.


 

FROM GASTROENTEROLOGY

Large sessile or flat colorectal polyps or laterally spreading lesions were most likely to contain covert malignancies when their location was rectosigmoid, their Paris classification was 0-Is or 0-IIa+Is, and they were nongranular, according to the results of a multicenter prospective cohort study of 2,106 consecutive patients reported in the September issue of Gastroenterology (doi: 10.1053/j.gastro.2017.05.047).

“Distal nongranular lesions have a high risk of occult SMIC [submucosal invasive cancer], whereas proximal, granular 0-IIa lesions, after a careful assessment for features associated with SMIC, have a very low risk,” wrote Nicholas G. Burgess, MD, of Westmead Hospital, Sydney, with his associates. “These findings can be used to inform decisions [about] which patients should undergo endoscopic submucosal dissection, endoscopic mucosal resection, or surgery.”

Source: American Gastroenterological Association

Many studies of colonic lesions have examined predictors of SMIC. Nonetheless, clinicians need more information on factors that improve clinical decision making, especially as colonic endoscopic submucosal dissection becomes more accessible, the researchers said. Large colonic lesions can contain submucosal invasive SMICs that are not visible on endoscopy, and characterizing predictors of this occurrence could help patients and clinicians decide between endoscopic submucosal dissection and endoscopic mucosal resection. To do so, the researchers analyzed histologic specimens from 2,277 colonic lesions above 20 mm (average size, 37 mm) that lacked overt endoscopic high-risk features. The study ran from 2008 through 2016, study participants averaged 68 years of age, and 53% were male. A total of 171 lesions (8%) had evidence of SMIC on pathologic review, and 138 lesions had covert SMIC. Predictors of overt and occult SMIC included Kudo pit pattern V, a depressed component (0-IIc), rectosigmoid location, 0-Is or 0-IIa+Is Paris classification, nongranular surface morphology, and larger size. After excluding lesions with obvious SMIC features – including serrated lesions and those with depressed components (Kudo pit pattern of V and Paris 0-IIc) – the strongest predictors of occult SMIC included Paris classification, surface morphology, size, and location.

“Proximal 0-IIa G or 0-Is granular lesions had the lowest risk of SMIC (0.7% and 2.3%), whereas distal 0-Is nongranular lesions had the highest risk (21.4%),” the investigators added. Lesion location, size, and combined Paris classification and surface topography showed the best fit in a multivariable model. Notably, rectosigmoid lesions had nearly twice the odds of containing covert SMIC, compared with proximal lesions (odds ratio, 1.9; 95% confidence interval, 1.2-3.0; P = .01). Other significant predictors of covert SMIC in the multivariable model included combined Paris classification, surface morphology (OR, 4.0; 95% CI, 1.2-12.7; P = .02), and increasing size (OR, 1.2 per 10-mm increase; 95% CI, 1.04-1.3; P = .01). Increased size showed an even greater effect in lesions exceeding 50 mm.

Clinicians can use these factors to help evaluate risk of invasive cancer in lesions without overt SMIC, the researchers said. “One lesion type that differs from the pattern is 0-IIa nongranular lesions,” they noted. “Once lesions with overt evidence of SMIC are excluded, these lesions have a low risk (4.2%) of harboring underlying cancer.” Although 42% of lesions with covert SMIC were SM1 (potentially curable by endoscopic resection), no predictor of covert SMIC also predicted SMI status.

Funders included Cancer Institute of New South Wales and Gallipoli Medical Research Foundation. The investigators had no conflicts of interest.

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