Clinicopathologic and endoscopic features of early-stage colorectal serrated adenocarcinoma

BMC Gastroenterol. 2017 Dec 12;17(1):158. doi: 10.1186/s12876-017-0702-x.


Background: Serrated adenocarcinoma (SAC) is a distinct colorectal carcinoma variant that accounts for approximately 7.5% of all advanced colorectal carcinomas. While its prognosis is worse than conventional carcinoma, its early-stage clinicopathologic features are unclear. We therefore aimed to clarify the clinicopathologic and endoscopic characteristics of early-stage SACs.

Methods: Forty consecutive early-stage SAC patients at Hiroshima University Hospital were enrolled; SACs were classified into epithelial serration (Group A, n = 17) and non-epithelial serration (Group B, n = 23) groups. Additionally, we classified serrated adenoma into 4 types: sessile serrated adenoma (SSA), traditional serrated adenoma (TSA), unclassified, and non-serrated adenoma type.

Results: There were significant differences between Groups A and B in terms of tumor size (27.6 vs. 43.1 mm), incidences of T1 carcinoma (71% vs. 13%), and having the same color as normal mucosa (47% vs. 17%), respectively (p <0.01). In SACs >20 mm, the incidence of T1 carcinoma in Group A (70%) was significantly greater than that in Group B (13%) (p <0.05). There were significant differences in 'Japan NBI Expert Team' type 3 and type V pit pattern classifications between the 2 groups. The average TSA-type tumor size (42.6 mm) was significantly larger than that of the SSA (17.2 mm) and non-serrated component types (18.3 mm). The incidences of submucosal invasion in SSA- (80%), unclassified- (100%), and non-serrated-type (100%) tumors were significantly higher than that in the TSA type (11%).

Conclusions: Epithelial serration in the cancerous area and a non-TSA background indicated aggressive behavior in early-stage SACs.

Keywords: Colorectal cancer; Narrow band imaging; Pit pattern; Serrated adenocarcinoma.

MeSH terms

  • Adenocarcinoma / classification
  • Adenocarcinoma / pathology*
  • Aged
  • Colonoscopy
  • Colorectal Neoplasms / classification
  • Colorectal Neoplasms / pathology*
  • Female
  • Humans
  • Male
  • Neoplasm Invasiveness
  • Neoplasm Staging