title: Differences between right- and left-sided colon cancer in patient characteristics, cancer morphology and histology.
abstract: OBJECTIVE
  Recently, the clinical and biological differences between right- and left-sided colon cancers have been widely debated. However, close analyses of these clinical differences, based on large-scale studies, have been scarcely reported.
  
  
  METHODS
  A total of 3552 consecutive Japanese colorectal cancer cases were examined and the clinical differences between right- and left-sided colon cancer cases were investigated.
  
  
  RESULTS
  The proportion of right-sided colon cancer was relatively high in patients aged less than 40 years (33%) and more than 80 years (43%). The proportion of right-sided colon cancer in patients aged 40-59 years was relatively low (male 22% and female 29%). In male patients the proportion increased in the 70-79 years age group (30%), while in female patients the proportion increased in the 60-69 years age group (39%). Right-sided colon cancer was more likely to be detected at an advanced stage (T1 stage; left 22%, right 15%) (P < 0.01) with severe symptoms. Polypoid-type early cancer was dominant in the left colon (left 59%; right 40%) (P < 0.01), while the proportion of flat-type early cancer in the right colon was significantly higher than that in the left colon (left 25%; right 44%) (P < 0.01).
  
  
  CONCLUSIONS
  Specific age distribution of right-sided colon cancer was observed and the difference between male and female patients was highlighted. Other clinical features also differed between right- and left-sided colon cancer, suggesting that different mechanisms may be at work during right and left colon carcinogenesis.
authors.affiliation: Department of Gastroenterology and Hepatology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Japan. torunawa@yahoo.co.jp
authors.forename: Toru
authors.initials: T
authors.lastname: Nawa
authors.forename: Jun
authors.initials: J
authors.lastname: Kato
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Kawamoto
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Okada
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kohno
authors.forename: Hisayuki
authors.initials: H
authors.lastname: Endo
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Shiratori
mesh_terms: D000230:Adenocarcinoma / Q000473:pathology*; D002288:Adenocarcinoma, Mucinous / Q000473:pathology*; D000328:Adult; D017677:Age Distribution; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D018279:Carcinoma, Signet Ring Cell / Q000473:pathology*; D002454:Cell Differentiation; D003110:Colonic Neoplasms / Q000473:pathology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D009367:Neoplasm Staging; D012042:Registries; D017678:Sex Distribution; D012737:Sex Factors