title: Surgical Resection of Primary Tumor in Asymptomatic or Minimally Symptomatic Patients With Stage IV Colorectal Cancer: A Canadian Province Experience.
abstract: BACKGROUND
  Surgical resection of the primary tumor in patients with stage IV colorectal cancer (CRC) remains controversial. Survival benefit reported in the literature has been attributed to the selection of younger and healthier patients with good performance status. We have recently reported that resection of the primary tumor improved survival of patients with stage IV CRC. In this study we examined survival benefit of surgery in patients with asymptomatic or minimally symptomatic primary tumor.
  
  
  METHODS
  A cohort of patients with stage IV CRC and asymptomatic or minimally symptomatic primary tumor, who were diagnosed during the period of 1992 to 2005, in the province of Saskatchewan Canada, was evaluated. The Kaplan-Meier method was used to determine survival. A multivariate Cox proportional hazard regression analysis was performed to determine prognostic importance of resection of primary tumor. A test for interaction was performed for resection of primary tumor and other important clinicopathological variables.
  
  
  RESULTS
  A total of 834 patients with a median age of 70 years (range, 22-93) and male:female ratio of 58:42 were identified. Among them 521 (63%) patients underwent surgery and 361 (43.3%) received chemotherapy. Patients who underwent surgery and received any chemotherapy had a median overall survival of 19.7 months (95% confidence interval [CI], 16.9-22.6) compared with 8.4 months (95% CI, 6.9-10.0) if they did not have surgery (P < .0001). In multivariate analysis, 5-fluorouracil-based chemotherapy (hazard ratio [HR], 0.43; 95% CI, 0.36-0.53), surgical resection of the primary tumor (HR, 0.47; 95% CI, 0.39-0.57), metastasectomy (HR, 0.48; 95% CI, 0.38-0.62), and second-line chemotherapy (HR, 0.72; 95% CI, 0.58-0.92) were correlated with superior survival. A test for interaction between ≥ 1 metastatic sites and surgery was significant, which suggests a larger benefit of surgery in patients with stage IVA disease.
  
  
  CONCLUSIONS
  Results of this large population-based cohort study suggest that resection of the primary tumor in asymptomatic or minimally symptomatic patients with stage IV CRC improved survival independent of other prognostic variables. The benefit was more pronounced in stage IVA disease.
authors.affiliation: Department of Oncology, Saskatchewan Cancer Agency, Saskatoon, Saskatchewan, Canada; Department of Community Health and Epidemiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada; Department of Oncology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada. Electronic address: shahid.ahmed@saskcancer.ca.
authors.forename: Shahid
authors.initials: S
authors.lastname: Ahmed
authors.affiliation: Department of Oncology, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Anthony
authors.initials: A
authors.lastname: Fields
authors.affiliation: Department of Oncology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Punam
authors.initials: P
authors.lastname: Pahwa
authors.affiliation: Department of Surgery, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Selliah
authors.initials: S
authors.lastname: Chandra-Kanthan
authors.affiliation: Department of Oncology, Saskatchewan Cancer Agency, Saskatoon, Saskatchewan, Canada; Department of Community Health and Epidemiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Adnan
authors.initials: A
authors.lastname: Zaidi
authors.affiliation: Department of Oncology, Saskatchewan Cancer Agency, Saskatoon, Saskatchewan, Canada; Department of Community Health and Epidemiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Duc
authors.initials: D
authors.lastname: Le
authors.affiliation: Department of Oncology, Saskatchewan Cancer Agency, Saskatoon, Saskatchewan, Canada; Department of Community Health and Epidemiology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Kamal
authors.initials: K
authors.lastname: Haider
authors.affiliation: Department of Oncology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Bruce
authors.initials: B
authors.lastname: Reeder
authors.affiliation: Department of Oncology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Anne
authors.initials: A
authors.lastname: Leis
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000601:surgery*; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D011379:Prognosis; D016016:Proportional Hazards Models; D012525:Saskatchewan; D015996:Survival Rate; D016896:Treatment Outcome; D055815:Young Adult
keywords: Asymptomatic patients; Primary tumor; Stage IV colorectal cancer; Surgery; Survival