Reply to Hurlstone et al.

We would like to thank Dr. Hurlstone and his colleagues for his discerning comments about the place of high-magnification chromoscopic colonoscopy (HMCC) and endoscopic ultrasonography in establishing the indication for endoscopic mucosal resection (EMR) for early colonic neoplasia. As mentioned by Hurlstone et al., many publications, including Western papers, have assessed the feasibility, reproducibility, and safety of EMR in the treatment of colonic polyps. EMR is currently regarded as a curative method of treatment for well-differentiated colonic cancer limited to the mucosa or invading less than one-third of the submucosa (sm1). In assessing the results with this method, our study was specifically designed to analyze both local recurrences and the risk of distant metastases after EMR procedures carried out exclusively in patients with early colorectal cancer.

Accurate preoperative evaluation of the depth of parietal infiltration is a clinical challenge for many authors in choosing the best treatment - either EMR alone in patients with mucosal/sm1 cancer or surgery in other cases. The study by Hurlstone et al. [1] demonstrated a strong correlation between the Kudo type V pit-pattern criteria examined using HMCC and submucosal infiltration. Pit types Vn(b) or Vn(c) in the Nagata criteria were found in 97 % of lesions with sm2 - sm3 invasion. However, the principal pitfall of this procedure is its low specificity - 50 % in the study by Hurlstone et al. [1] and 31 % in another paper published by the same team [2], with an accuracy ranging from 59 % to 78 % [1] [2] [3]. Overstaging leads to unnecessary and costly surgery rather than safer endoscopic management. Similarly, in the study by Bianco et al. [3], 50 % of polyps with pit-pattern V showed a depth of infiltration of less than 1000 µm in the definitive histological specimens, showing that surgery represented excessive treatment in these cases.

Endoscopic ultrasonography (EUS) using high-frequency miniprobes was reported by Hurlstone et al. [2] to be more accurate than magnification in patients with this indication. The use of “standard” EUS to distinguish between T1 and T2 lesions is now well established. While high-frequency miniprobes and high-resolution electronic probes allow precise evaluation of the depth of mural infiltration and can diagnose deep involvement of the submucosa, their accuracy in distinguishing between sm1 and sm2 lesions is probably low, although it has not been clearly evaluated. In addition, there is no evidence that EUS is superior to the “lifting sign” [4] [5]. A lack of lifting of the lesion after saline injection is associated with sm3 infiltration.

In conclusion, we believe than every colonic polyp staged as T1 on EUS that lifts homogeneously after saline injection must be resected endoscopically. Only histological examination of the resected specimen makes it possible to determine whether the endoscopic treatment has been curative or not, or whether additional surgical resection is necessary. Pit-pattern analysis using magnification endoscopy - or perhaps even better with confocal endomicroscopy - to distinguish a subgroup of polyps associated with a high risk of deep mural involvement may have a role in not contraindicating EMR, due to its low specificity; however, it is probably better as an indication for en bloc endoscopic mucosal resection in these cases, allowing precise evaluation of the depth of tumor infiltration.

Competing interests: None

References

• 1 Hurlstone D P, Cross S S, Adam I. et al . Endoscopic morphological anticipation of submucosal invasion in flat and depressed colorectal lesions: clinical implications and subtype analysis of the Kudo type V pit-pattern using high-magnification-chromoscopic colonoscopy.  Colorectal Dis. 2004;  6 369-375
• 2 Hurlstone D P, Brown S, Cross S S. et al . High magnification chromoscopic colonoscopy or high frequency 20 MHz mini probe endoscopic ultrasound staging for early colorectal neoplasia: a comparative prospective analysis.  Gut. 2005;  54 1585-1589
• 3 Bianco M A, Rotondano G, Marmo R. et al . Predictive value of magnification chromoendoscopy for diagnosing invasive neoplasia in nonpolypoid colorectal lesions and stratifying patients for endoscopic resection or surgery.  Endoscopy. 2006;  38 470-476
• 4 Ishiguro A, Uno Y, Ishiguro Y. et al . Correlation of lifting versus non-lifting and microscopic depth of invasion in early colorectal cancer.  Gastrointest Endosc. 1999;  50 329-333
• 5 Kato H, Haga S, Endo S. et al . Lifting of lesions during endoscopic mucosal resection (EMR) of early colorectal cancer: implications for the assessment of resectability.  Endoscopy. 2001;  33 568-573