How To Diagnose Early Rectal Adenocarcinoma? Endoscopic Features and Predictors of Submucosal Invasion at National Cancer Center Tokyo

Abstract

Background: Rectal cancer is usually diagnosed at late stage, however, the incidence of early cancer (confined to the mucosa and submucosa) is increasing in Japan. Endoscopic resection improves patients's QOL and is the accepted treatment for mucosal cancer, however, remains controversial in submucosal tumors. In this regard, endoscopic differences between mucosal and submucosal tumors will determine treatment strategies, however have been scarcely studied and the role of endoscopic treatment is still unclear Aim: The aim of this study was to evaluate the endoscopic features of mucosal and submucosal rectal adenocarcinoma and the endoscopic predictors of submucosal invasion. Material and Methods: Early rectal adenocarcinoma diagnosed between October, 1988 and November, 2002 were the subject of the study. Age, gender, location (Rs, Ra and Rb), size, macroscopic type, depressed component (IIc), growth type: polypoid growth (PG), non polypoid growth (NPG), clinical pit pattern (non invasive, invasive) were analyzed to predict submucosal invasion. Treatment (endoscopic, surgical) and lymph node metastases (LNM) data were also analyzed. Results: There were 268 early rectal cancers, 196 (73%) mucosal and 72 (27%) submucosal. Overall mean age and size were 62±10.7 years and 15±8.4 mm respectively. There were no significant differences in age, gender, location and macroscopic type and the layer of invasion, however, mean size, presence of IIc component, NPG and invasive pattern were significantly different between mucosal and submucosal tumors. Multivariate analysis revealed that invasive pattern (OR = 68), NPG (OR = 17) and size ≥15 mm (OR = 14) were independent factors predicting submucosal invasion. Endoscopic treatment was performed in all mucosal resections (curative rate:100%). Submucosal tumors were treated endoscopically in 26 (36%) and surgically in 46 (64%) cases. Among the endoscopic resected lesion, 9 (34%) lesions invaded ≤1000 um (sm1) and 17 (66%) invaded >1000 um (sm2). Additional surgery was performed in sm2 cases. LNM was found in 7 out of 72 (10%) submucosal tumors. Conclusions: Endoscopic resection effectively removed most early rectal adenocarcinomas. Invasive pit pattern, NPG and size ≥15 mm are accurate predictive factors of submucosal invasion and useful to define the therapeutic strategy. Endoscopic diagnosis might of early rectal adenocarcinoma is feasible and might reduce unnecessary surgical procedures.