title: The Worse Prognosis of Right-Sided Compared with Left-Sided Colon Cancers: a Systematic Review and Meta-analysis.
abstract: BACKGROUND
  Right-sided colon cancers (RCC) and left-sided colon cancers (LCC) are of different embryological origins, and various differences exist between them. However, the survival difference has not been assessed. The aim of this meta-analysis was to quantify the prognostic differences between RCC and LCC.
  
  
  METHODS
  Fifteen studies that compared the prognosis of colon cancer according to tumor location were identified. The effects of tumor location on survival outcome were assessed.
  
  
  RESULTS
  Patients with RCC had a significantly worse prognosis than did those with LCC in overall survival (OS) (hazard ratio (HR) = 1.14, 95 % confidence interval (CI) 1.06-1.22, p < 0.01). Our subgroup analyses demonstrated significant prognostic differences in Western countries (HR = 1.15, 95 % CI 1.08-1.23, p < 0.01), a nationwide database (HR = 1.15, 95 % CI 1.05-1.27, p = 0.01), and a stage-adjusted analysis (HR = 1.14, 95 % CI 1.05-1.24, p < 0.01).
  
  
  CONCLUSIONS
  These findings demonstrate that tumor location is associated with prognosis in colorectal cancer patients, and those with RCC have a significantly worse prognosis than those with LCC in terms of OS. RCC should be treated distinctively from LCC, and the establishment of standardized management for colon cancer by tumor location is needed.
authors.affiliation: Department of Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, Tokyo, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Yahagi
authors.affiliation: Department of Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, Tokyo, Japan. okabayashikoji@gmail.com.
authors.forename: Koji
authors.initials: K
authors.lastname: Okabayashi
authors.affiliation: Department of Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, Tokyo, Japan.
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Hasegawa
authors.affiliation: Department of Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, Tokyo, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Tsuruta
authors.affiliation: Department of Surgery, Keio University School of Medicine, 35 Shinanomachi, Shinjyuku-ku, Tokyo, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kitagawa
mesh_terms: D003110:Colonic Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D006801:Humans; D009367:Neoplasm Staging; D011379:Prognosis; D016016:Proportional Hazards Models
keywords: Colon cancer; Left-sided colon; Prognosis; Right-sided colon