title: Oxaliplatin-based first-line chemotherapy is associated with improved overall survival compared to first-line treatment with irinotecan-based chemotherapy in patients with metastatic colorectal cancer - Results from a prospective cohort study.
abstract: OBJECTIVE
  Several randomized trials investigating the preferable first-line combination chemotherapy regimen for metastatic colorectal cancer have shown inconsistent findings. Because a substantial number of patients are still being treated with "chemo-only" first-line therapies without targeted agents, we compared overall survival (OS) of patients treated in routine practice with oxaliplatin-fluoropyrimidine and irinotecan-fluoropyrimidine.
  
  
  METHODS
  Using the database of the Tumor Registry Colorectal Cancer, we identified 605 patients with metastatic colorectal cancer who received first-line fluoropyrimidine combination chemotherapy with either oxaliplatin (n=430) or irinotecan (n=175). The Tumor Registry Colorectal Cancer is a cohort study that prospectively documents treatment of colorectal cancer by office-based medical oncologists in Germany and has recruited over 5,000 patients. OS was estimated using the Kaplan-Meier method, and a multivariate Cox proportional hazard model was used to adjust for potentially confounding variables.
  
  
  RESULTS
  Median OS was 26.8 (95% confidence interval [CI] 22.4-31.9) months with an oxaliplatin-fluoropyrimidine combination and 18.3 (95% CI 15.1-23.2) months with irinotecan-fluoropyrimidine first-line "chemo-only" therapy. Median progression-free survival was 9.0 (8.1-10.2) and 7.9 (7.2-10.2) months, respectively. The difference in OS was confirmed if analysis was restricted to patients with synchronous metastases (no prior treatment). Among other variables, proportion of patients receiving any second-line therapy did not differ between groups. Oxaliplatin-based first-line therapy was associated with improved OS in multivariate analysis adjusted for potentially confounding variables (hazard ratio 0.678, 95% CI 0.510-0.901, P=0.007).
  
  
  CONCLUSIONS
  In clinical routine practice, first-line treatment with oxaliplatin-fluoropyrimidine combination chemotherapy compared to irinotecan-fluoropyrimidine combination is associated with improved survival in patients with metastatic colorectal cancer, independent of all examined potentially confounding factors.
authors.affiliation: Praxis für Interdisziplinäre Onkologie und Hämatologie, Freiburg, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Marschner
authors.affiliation: Klinik für Tumorbiologie, Freiburg, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Arnold
authors.affiliation: Hämatologisch - Onkologische Praxis Altona, Hamburg, Germany.
authors.forename: Erik
authors.initials: E
authors.lastname: Engel
authors.affiliation: Hämatologisch - Onkologische Gemeinschaftspraxis, Nordhorn, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Hutzschenreuter
authors.affiliation: Fachinternistische Gemeinschaftspraxis und Therapiezentrum, Witten, Germany.
authors.forename: Jacqueline
authors.initials: J
authors.lastname: Rauh
authors.affiliation: Onkologische Praxis, Hildesheim, Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Freier
authors.affiliation: Clinical Epidemiology and Health Economics, iOMEDICO, Freiburg, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Hartmann
authors.affiliation: Statistics, iOMEDICO, Freiburg, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Frank
authors.affiliation: Clinical Epidemiology and Health Economics, iOMEDICO, Freiburg, Germany.
authors.forename: Martina
authors.initials: M
authors.lastname: Jänicke
keywords: cohort studies; colorectal neoplasms; epidemiology; irinotecan; oxaliplatin; treatment outcome