title: Conditional survival after surgical resection of colorectal liver metastasis: an international multi-institutional analysis of 949 patients.
abstract: BACKGROUND
  Traditionally, survival estimates have been reported solely as survival from the time of surgery, but future survival probability likely changes based on the survival time already accumulated after therapy-otherwise known as conditional survival (CS). We sought to assess the comparative performance of various colorectal liver metastasis prognostic scoring systems, as well as to investigate the CS of patients who underwent resection of colorectal liver metastasis.
  
  
  METHODS
  Between 1982 and 2008, 949 patients who underwent colorectal liver metastasis resection were identified from an international multi-institutional database. Various prognostic scoring systems were evaluated using Cox proportional hazards models and calculated concordance index (c). CS estimates were calculated as CS = S((x+5))/S((x)).
  
  
  RESULTS
  Overall survival after liver resection was 65% at 3 years and 45% at 5 years, with a median survival of 52 months. All of the prognostic scoring systems had poor-to-moderate prognostic discriminatory ability (Fong c = 0.57, Nordlinger c = 0.56, Memorial Sloan-Kettering Cancer Center nomogram c = 0.58). Using CS, the probability of surviving an additional 5 years, given that the patient had already survived 1, 3, or 5 years, was 41%, 40%, or 50%, respectively. The inadequate performance of the prognostic scoring systems was explained by the fact that as survival from liver resection increased from 0 to 5 years, the 5-year observed CS improved substantially for patients who were initially predicted to have poor survival at the time of surgery.
  
  
  CONCLUSIONS
  Colorectal liver metastasis prognostic scoring systems have fair-to-moderate performance. CS can provide more accurate prognostic information for patients and physicians after colorectal liver metastasis resection and should be incorporated into the quantification of survival.
authors.affiliation: Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Hari
authors.initials: H
authors.lastname: Nathan
authors.forename: Mechteld C
authors.initials: MC
authors.lastname: de Jong
authors.forename: Carlo
authors.initials: C
authors.lastname: Pulitano
authors.forename: Dario
authors.initials: D
authors.lastname: Ribero
authors.forename: Jennifer
authors.initials: J
authors.lastname: Strub
authors.forename: Gilles
authors.initials: G
authors.lastname: Mentha
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Gigot
authors.forename: Richard D
authors.initials: RD
authors.lastname: Schulick
authors.forename: Michael A
authors.initials: MA
authors.lastname: Choti
authors.forename: Luca
authors.initials: L
authors.lastname: Aldrighetti
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Capussotti
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Pawlik
mesh_terms: D000328:Adult; D015331:Cohort Studies; D003110:Colonic Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D018572:Disease-Free Survival; D005260:Female; D006305:Health Status Indicators; D006498:Hepatectomy; D006801:Humans; D008113:Liver Neoplasms / Q000401:mortality* / Q000556:secondary / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012004:Rectal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000628:therapy; D012189:Retrospective Studies; D015996:Survival Rate