title: Right colon cancer: Left behind.
abstract: BACKGROUND
  Prognosis of colon cancer (CC) has steadily improved during the past three decades. This trend, however, may vary according to proximal (right) or distal (left) tumor location. We studied if improvement in survival was greater for left than for right CC.
  
  
  METHODS
  We included all CC recorded at the Geneva population-based registry between 1980 and 2006. We compared patients, tumor and treatment characteristics between left and right CC by logistic regression and compared CC specific survival by Cox models taking into account putative confounders. We also compared changes in survival between CC location in early and late years of observation.
  
  
  RESULTS
  Among the 3396 CC patients, 1334 (39%) had right-sided and 2062 (61%) left-sided tumors. In the early 1980s, 5-year specific survival was identical for right and left CCs (49% vs. 48%). During the study period, a dramatic improvement in survival was observed for patients with left-sided cancers (Hazard ratio [HR]: 0.42, 95% confidence interval [CI]: 0.29-0.62, p < 0.001) but not for right CC patients (HR: 0.76, 95% CI: 0.50-1.14, p = 0.69). As a consequence, patients with distal CC have a better outcome than patients with proximal CC (HR for left vs. right CC: 0.81, 95% CI: 0.72-0.90, p < 0.001).
  
  
  CONCLUSIONS
  Our data indicate that, contrary to left CC, survival of patients with right CC did not improve since 1980. Of all colon cancer patients, those with right-sided lesions have by far the worse prognosis. Change of strategic management in this subgroup is warranted.
authors.affiliation: Division of Coloproctology, Clinique Hirslanden La Colline, Geneva, Switzerland. Electronic address: pascalgervaz@gmail.com.
authors.forename: P
authors.initials: P
authors.lastname: Gervaz
authors.affiliation: Geneva Cancer Registry, Institute of Global Health, Geneva University of Medicine, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Usel
authors.affiliation: Geneva Cancer Registry, Institute of Global Health, Geneva University of Medicine, Switzerland.
authors.forename: E
authors.initials: E
authors.lastname: Rapiti
authors.affiliation: Division of Genetic Medicine, Geneva University Hospital, Geneva, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Chappuis
authors.affiliation: Geneva Cancer Registry, Institute of Global Health, Geneva University of Medicine, Switzerland.
authors.forename: I
authors.initials: I
authors.lastname: Neyroud-Kaspar
authors.affiliation: Geneva Cancer Registry, Institute of Global Health, Geneva University of Medicine, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Bouchardy
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D000368:Aged; D000369:Aged, 80 and over; D002430:Cecal Neoplasms / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D044682:Colon, Ascending / Q000473:pathology*; D044683:Colon, Descending / Q000473:pathology*; D044684:Colon, Transverse / Q000473:pathology*; D003110:Colonic Neoplasms / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D012042:Registries; D012811:Sigmoid Neoplasms / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D015996:Survival Rate / Q000639:trends; D013557:Switzerland / Q000453:epidemiology
keywords: Cancer registry; Colon cancer; Location; Population-based study; Survival