Depth of submucosal invasion vs. Haggitt level as prognostic predictors of pedunculated‑type early‑stage colorectal cancer removed by endoscopic resection

Additional surgery is considered when deep submucosal (SM) invasion (≥1,000 µm) is pathologically observed following the endoscopic resection of early-stage colorectal cancer (eCRC). The Japanese Society for Cancer of the Colon and Rectum (JSCCR) states that the depth of SM invasion be measured from the lower border of the muscularis mucosae (MM) when MM can be identified/estimated and from the lesion's surface when it cannot, irrespective of macroscopic types. In MM-tangled pedunculated eCRC cases, SM invasion depth should be measured from the reference line, which is the boundary between the tumor head and stalk. In the present study, in order to validate these measuring rules compared with the Haggitt classification, 73 consecutive pedunculated eCRC cases were analyzed. Using Elastica-van Gieson and desmin immunostaining, 37, 10, 18 and eight cases were diagnosed as pTis (without SM invasion by JSCCR)/Haggitt level (HL) 0, pTis/HL1-2 (head invasion), pT1b (SM invasion ≥1,000 µm)/HL1-2 and pT1b/HL3 (stalk invasion), respectively. No lymph node metastasis was observed. Recurrence occurred in one pTis/HL1 case; however, no pT1b/HL1-3 cases experienced recurrence. These results suggest that the pedunculated eCRC may be overstaged by the JSCCR rule in terms of adverse outcomes. The Haggitt classification, which evaluates HL1-3 as a shallow SM invasion, may be more useful when considering additional surgery.