title: A retrospective cohort study of metastatic colorectal cancer patients treated with oxaliplatin-based chemotherapy, with an exploratory analysis of changing serum carcinoembryonic antigen levels.
abstract: OBJECTIVE
  To examine the relationship between changes in serum carcinoembryonic antigen (CEA) levels and survival during oxaliplatin-based chemotherapy for metastatic colorectal cancer (mCRC).
  
  
  METHODS
  A retrospective review of 142 patients with mCRC who were treated with oxaliplatin-based chemotherapies (mostly FOLFOX 6 or XELOX) by St Vincent's Hospital, from October 1999 until 30 November 2007. Survival analysis was used to determine median overall survival (OS) from commencement of chemotherapy. A CEA response was defined by ≥50% decline compared with baseline, maintained on two consecutive occasions at least 4 weeks apart. The Cox proportional hazard model and a landmark analysis at 3 months were used to evaluate survival differences between CEA responders (rCEA) and non-responders (non-rCEA).
  
  
  RESULTS
  The median OS was 14.7 months. Using an intention-to-treat analysis, 76 (53.5%) patients achieved a CEA response, while 66 (46.5%) did not. Using the landmark analysis at 3 months, rCEA had a longer survival than non-rCEA (median 16.0 vs 7.8 months, P < 0.0001). The hazard ratio for patients dying of mCRC in non-rCEA was 2.2 (P < 0.0001). In multivariate analysis, CEA response and better baseline Eastern Cooperative Oncology Group (ECOG) predicted for survival (P < 0.0001 for both), while age, gender and histology grade did not.
  
  
  CONCLUSIONS
  The median OS of our patients is similar to published randomized trials. A CEA response of ≥50% at 3 months and good ECOG were independent predictors of OS of patients with mCRC treated with oxaliplatin-based chemotherapies.
authors.affiliation: Department of Medical Oncology, St Vincent's Hospital, Fitzroy, Australia.
authors.forename: Say Liang
authors.initials: SL
authors.lastname: Ng
authors.forename: William I
authors.initials: WI
authors.lastname: Burns
authors.forename: Raymond D
authors.initials: RD
authors.lastname: Snyder
authors.forename: Genni M
authors.initials: GM
authors.lastname: Newnham
authors.forename: Sue-Anne
authors.initials: SA
authors.lastname: McLachlan
authors.forename: Danny
authors.initials: D
authors.lastname: Liew
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Dowling
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage* / Q000009:adverse effects; D000069287:Capecitabine; D002272:Carcinoembryonic Antigen / Q000097:blood*; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000097:blood* / Q000188:drug therapy* / Q000473:pathology; D003841:Deoxycytidine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives; D018572:Disease-Free Survival; D005260:Female; D005472:Fluorouracil / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives; D006801:Humans; D002955:Leucovorin / Q000008:administration & dosage / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D009944:Organoplatinum Compounds / Q000008:administration & dosage / Q000009:adverse effects; D000077150:Oxaliplatin; D010071:Oxaloacetates; D011379:Prognosis; D012189:Retrospective Studies; D016019:Survival Analysis; D016896:Treatment Outcome
chemical_list: D002272:Carcinoembryonic Antigen; D009944:Organoplatinum Compounds; D010071:Oxaloacetates; D000077150:Oxaliplatin; D003841:Deoxycytidine; D000069287:Capecitabine; D002955:Leucovorin; D005472:Fluorouracil