title: Two subtypes in colorectal mucinous carcinoma in relation to microsatellite instability.
abstract: OBJECTIVE
  Although some investigators have attempted to divide colorectal mucinous adenocarcinoma into two entities, there have been few reports describing microsatellite instability of each subtype. In this study, we elucidated the clinicopathological features of subtypes in mucinous carcinoma, especially the relationship between microsatellite instability and each subtype.
  
  
  METHODS
  The present study included 33 patients with mucinous colorectal cancer. The 33 patients were classified into two groups; the papillotubular type group (n = 22) and the mucocellular type group (n = 11). The clinicopathological aspects and microsatellite instability were examined.
  
  
  RESULTS
  Significant differences were found between the papillotubular type group and the mucocellular type group regarding the following findings such as lymphatic invasion, lymph node metastasis, peritoneal metastasis, and Dukes stage. The mucocellular type group had 2 cases with high-frequency microsatellite instability, 7 cases with low-frequency microsatellite instability and 2 cases with microsatellite stability. Conversely, the papillotubular type group included 12 cases with high-frequency microsatellite instability, 3 cases with low-frequency microsatellite instability and 7 cases with microsatellite stability. The ratio of cases with high-frequency microsatellite instability in the mucocellular type group (18.1%) was significantly lower than that of the papillotubular type group (54.5%) (P = 0.0463). The 5-year survival rate of the mucocellular type group (29.1%) was significantly lower than that of the papillotubular type group (70.3%) (P = 0.0282).
  
  
  CONCLUSIONS
  Colorectal mucinous carcinoma needs to be classified into two groups, papillotubular type and mucocellular type, because of significant differences in microsatellite instability and patients' survival.
authors.affiliation: Third Department of Surgery, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Kondo
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: D002288:Adenocarcinoma, Mucinous / Q000235:genetics* / Q000473:pathology*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology*; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D018895:Microsatellite Repeats; D008875:Middle Aged; D011379:Prognosis