title: Systematic review of prognostic factors related to overall survival in patients with stage IV colorectal cancer and unresectable metastases.
abstract: BACKGROUND
  With the improvements in newer chemotherapeutic agents, the role of primary tumour resection in patients with stage IV colorectal cancer is controversial. In many cases primary tumour resection is still favoured as first-line management. However, a detailed understanding of independent prognostic factors related to survival is necessary before making this decision.
  
  
  METHODS
  A literature search was conducted using Medline and Embase. Studies that performed multivariate analysis on overall survival of patients with incurable stage IV colorectal cancer were included in this review.
  
  
  RESULTS
  Fourteen retrospective studies involving 3209 patients were included. Clinical variables analysed to consistently have independent prognostic significance for long-term survival included the patients' performance status (<2), volume of liver metastases (<50%), nodal stage (N0), disease-free resection margins, and treatment with chemotherapy and/or primary tumour resection. Cancer antigen (CA) 19-9, low albumin, elevated ALP levels, apical lymph node involvement, presence of ascites, and postoperative transfusion were each assessed by only one study and found to be independently associated with survival. Factors inconsistently reported to have independent prognostic significance were age, ASA score, preoperative CEA levels, primary tumour location, tumour size and differentiation, peritoneal dissemination, and extrahepatic metastases.
  
  
  CONCLUSIONS
  Each patient should be reviewed individually on the basis of the above independent prognostic factors before deciding to resect the primary tumour. Patients with a poor performance status, extensive hepatic metastases, and extensive nodal disease detected preoperatively are less likely to have a survival benefit. Nonsurgical approaches to manage these patients should be given careful consideration.
authors.affiliation: Department of Surgery, School of Medicine & Dentistry and North Queensland Centre for Cancer Research, James Cook University, Townsville, QLD 4814, Australia. andrew.stillwell@jcu.edu.au
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Stillwell
authors.forename: Yik-Hong
authors.initials: YH
authors.lastname: Ho
authors.forename: Craig
authors.initials: C
authors.lastname: Veitch
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000556:secondary* / Q000628:therapy; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D003082:Colectomy / Q000379:methods / Q000401:mortality; D015179:Colorectal Neoplasms / Q000401:mortality* / Q000473:pathology* / Q000628:therapy; D005260:Female; D006801:Humans; D008297:Male; D009361:Neoplasm Invasiveness / Q000473:pathology*; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D010166:Palliative Care / Q000379:methods*; D011379:Prognosis; D018570:Risk Assessment; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome