title: Association between palliative resection of the primary tumor and overall survival in a population-based cohort of metastatic colorectal cancer patients.
abstract: BACKGROUND
  The impact of palliative resection of the primary tumor on outcomes in patients with metastatic colorectal cancer (mCRC) remains unclear. The primary objective of this study was to evaluate the association between palliative resection and overall survival (OS) in a population-based cohort of mCRC.
  
  
  METHODS
  Patients diagnosed with mCRC between 2006 and 2008 and treated at the BC Cancer Agency were reviewed. Survival analysis was conducted using Kaplan-Meier methods. Cox proportional hazards regression models were fitted to evaluate the relationship between palliative resection and OS while controlling for potential confounders, such as age, gender, Eastern Cooperative Oncology Group status, carcinoembryonic antigen level, primary tumor location, metastatic site and number, and receipt of systemic therapy. To adjust for the heterogeneity and selection bias between the group that underwent palliative resection and the group that did not, a propensity score-matched analysis was also performed.
  
  
  RESULTS
  A total of 517 patients were included. Among these cases, 378 (73 %) patients underwent palliative resection of their primary tumor, and 139 (27 %) patients did not. A total of 327 patients (63 %) were treated with palliative chemotherapy. Palliative resection was associated with a longer median OS (17.9 vs. 7.9 months) and more favorable unadjusted and adjusted hazard ratios (HRs) for death (HR 0.46, 95 % CI 0.37-0.56, p < 0.0001 and HR 0.56, 95 % CI 0.40-0.78, p = 0.0007, respectively) when compared with no resection. In a propensity score-matched analysis, prognosis was also more favorable in the resected group (p = 0.0017).
  
  
  CONCLUSIONS
  In this cohort of mCRC patients, palliative resection of the primary tumor was associated with improved OS.
authors.affiliation: Division of Medical Oncology, University of British Columbia, British Columbia Cancer Agency, Vancouver, BC, Canada.
authors.forename: Gillian
authors.initials: G
authors.lastname: Gresham
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Renouf
authors.forename: Matthew
authors.initials: M
authors.lastname: Chan
authors.forename: Hagen F
authors.initials: HF
authors.lastname: Kennecke
authors.forename: Howard J
authors.initials: HJ
authors.lastname: Lim
authors.forename: Carl
authors.initials: C
authors.lastname: Brown
authors.forename: Winson Y
authors.initials: WY
authors.lastname: Cheung
mesh_terms: D000368:Aged; D002170:Canada / Q000453:epidemiology; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology / Q000401:mortality* / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D010166:Palliative Care / Q000379:methods*; D011183:Postoperative Complications; D011379:Prognosis; D057216:Propensity Score; D015996:Survival Rate