Reply to Froehlich

We thank F. Froelich for his comments on our recent publication and we would like to clarify and expand on some points.

We too were surprised to find that the overall resection rate for diminutive polyps using cold biopsy polypectomy (CBP) was only 39 %. This, however, was mainly skewed by the 24 % resection rate observed in hyperplastic polyps compared with the 62 % resection rate in adenomas (P = 0.006). Adenoma resection is the most relevant outcome measure and the reported adenoma resection rate is clearly unacceptable. The only other large published study assessing CBP for diminutive polyps reported an adenoma complete resection rate of 82 % and also noted the discrepancy between the adenoma/nonadenoma resection rates [1]. Given the differences in methodologies for assessing polypectomy resection between the studies we suspect that the study by Woods et al. overestimates complete resection rates. Our protocol provided a complete specimen of the polypectomy site rather than random samples.

Theoretically the polyp resection rate using forceps may be a function of polyp diameter, polyp depth/thickness, forceps characteristics such as cusp diameter/depth, as well as the technique utilized in polyp resection and assessment of the polypectomy site. In terms of predictors for complete resection, in our study polyps < 3 mm were more likely to be resected than those  > 3 mm (50 % vs. 36 %); however, this did not reach statistical significance, possibly due to the small sample size. With regard to the number of bites as a predictor of resection, the more resections that are required the less likely that the polyp will be completely resected, possibly due to tiny islands left between the resections. This has been demonstrated for endoscopic mucosal resection of large polyps and should also apply to forceps polypectomy [2].

We read with interest the technique for CBP described by Froelich. The technique for CBP is variable among endoscopists. Although we routinely washed the polypectomy site following resection to assess for residual tissue, we did not obtain underwater images of the polypectomy site. This is an interesting method for assessing for residual tissue, which may improve resection rates. However, to our knowledge this method has not been validated in this setting; it would be worth assessing this method in a prospective study.

It has been suggested that “cold forceps resection is undoubtedly the quickest way to resect small polyps with the lowest complication rate and the highest polyp retrieval rate.” We agree that CBP is quick; however, the same applies to cold snare techniques, with a recent study reporting a mean polypectomy/retrieval time of less than 15 s [3]. There are no published comparative studies confirming that CBP is associated with fewer complications compared with cold snare polypectomy. CBP has a favorable complication profile, which is related to the absence of cautery and this applies to cold snare techniques as well. Finally, with the exception of tiny polyps, retrieval rates with snare polypectomy have been reported as high as 100 % [3]. Furthermore, in one model it has been suggested that it is not cost-effective to retrieve diminutive polyps for histological assessment [4].

A lot of research into improving colonoscopy outcomes has concentrated on improving colonoscopy completion rates and adenoma detection. There is a paucity of data on the efficacy of polypectomy using objective protocols. If we are to improve on the outcomes of colonoscopy as a tool for cancer prevention this needs to be addressed with objective evaluation of polypectomy outcomes.

References

• 1 Woods A, Sanowski R A, Wadas D D et al. Eradication of diminutive polyps: a prospective evaluation of bipolar coagulation versus conventional biopsy removal.  Gastrointest Endosc. 1989;  35 536-540
• 2 Moss A, Bourke M J, Williams S J et al. Endoscopic mucosal resection outcomes and prediction of submucosal cancer from advanced colonic mucosal neoplasia.  Gastroenterology. 2011;  140 1909-1918
• 3 Deenadayalu V P, Rex D K. Colon polyp retrieval after cold snaring.  Gastrointest Endosc. 2005;  62 253-256
• 4 Hassan C, Pickhardt P J, Rex D K. A resect and discard strategy would improve cost-effectiveness of colorectal cancer screening.  Clin Gastroenterol Hepatol. 2010;  8 865-869