title: Microsatellite instability in poorly differentiated colorectal adenocarcinoma, particularly in relation to two subtypes.
abstract: OBJECTIVE
  There have been a few reports indicating the characteristics of poorly differentiated colorectal adenocarcinoma by dividing it into subtypes. However, we have not found any reports describing microsatellite instability (MSI) of each subtype. In this study, we elucidated the clinicopathological features of subtypes in the poorly differentiated adenocarcinoma, especially the relationship between MSI and each subtype.
  
  
  METHODS
  The present study included 28 cases with poorly differentiated adenocarcinoma. The 28 cases were classified into two groups; the solid group and the non-solid group. For each group, the clinicopathological aspects and MSI were examined.
  
  
  RESULTS
  No significant differences were noted between the solid group and the non-solid group in terms of clinicopathological findings excluding male/female ratio. The 5-year survival rate of the solid group (38.5%) was significantly higher than that of the non-solid group (0.00%) (p=0.0013). The ratio of cases with MSI-H in the solid group (80.0%=12/15) was significantly higher than that of the non-solid group (30.8%=4/13) (p=0.0087).
  
  
  CONCLUSIONS
  The incidence of MSI as well as the prognosis was different between solid and non-solid type with poorly differentiated colorectal adenocarcinoma. Therefore, we think that poorly differentiated colorectal adenocarcinoma should be classified into two subtypes: solid type and non-solid type when analysis for poorly differentiated adenocarcinoma is performed.
authors.affiliation: Department of Surgery, Nihon University School of Medicine, Tokyo, Japan. hidekim@med.nihon-u.ac.jp
authors.forename: Hideki
authors.initials: H
authors.lastname: Masuda
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Abe
authors.forename: Tadatoshi
authors.initials: T
authors.lastname: Takayama
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D000368:Aged; D020137:Base Pair Mismatch / Q000235:genetics; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D005260:Female; D042822:Genomic Instability / Q000235:genetics*; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics*; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D015996:Survival Rate