title: Conditional survival in advanced colorectal cancer and surgery.
abstract: BACKGROUND
  Recent data show patients with advanced colorectal cancer (CRC) are surviving longer. What is unknown is how specific treatment modalities affect long-term survival. Conditional survival, or survival prognosis based on time already survived, is becoming an acceptable means of estimating prognosis for long-term survivors. We evaluated the impact of cancer-directed surgery on long-term survival in patients with advanced CRC.
  
  
  METHODS
  We used Surveillance, Epidemiology, and End Results data to identify 64,956 patients with advanced (Stage IV) CRC diagnosed from 2000-2009. Conditional survival estimates by stage, age, and cancer-directed surgery were obtained based on Cox proportional hazards regression model of disease-specific survival.
  
  
  RESULTS
  A total of 64,956 (20.1%) patients had advanced disease at the time of diagnosis. The proportion of those patients who underwent cancer-directed surgery was 65.1% (n = 42,176). Cancer-directed surgery for patients with advanced stage disease was associated with a significant improvement in traditional survival estimates compared to patients who did not undergo surgery (hazard ratio = 2.22 [95% confidence interval, 2.17-2.27]). Conditional survival estimates show improvement in conditional 5-y disease-specific survival across all age groups, demonstrating sustained survival benefits for selected patients with advanced CRC.
  
  
  CONCLUSIONS
  Five-year disease-specific conditional survival improves dramatically over time for selected patients with advanced CRC who undergo cancer-directed surgery. This information is important in determining long-term prognosis and will help inform treatment planning for advanced CRC.
authors: Department of Surgery, University of Michigan, North Campus Research Complex, Ann Arbor, Michigan.
authors: Lauren M
authors: LM
authors: Wancata
authors: Department of Biostatistics, University of Michigan, Ann Arbor, Michigan.
authors: Mousumi
authors: M
authors: Banerjee
authors: Department of Biostatistics, University of Michigan, Ann Arbor, Michigan.
authors: Daniel G
authors: DG
authors: Muenz
authors: Department of Medicine, Division of Metabolism, Endocrinology & Diabetes & Hematology/Oncology, University of Michigan, North Campus Research Complex, Ann Arbor, Michigan.
authors: Megan R
authors: MR
authors: Haymart
authors: Department of Surgery, Dartmouth-Hitchcock Medical Center, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire. Electronic address: sandra.l.wong@hitchcock.org.
authors: Sandra L
authors: SL
authors: Wong
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003106:Colon / Q000473:pathology; D015179:Colorectal Neoplasms / Q000401:mortality* / Q000473:pathology / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D012007:Rectum / Q000473:pathology; D018426:SEER Program; D014481:United States / Q000453:epidemiology
keywords: Advanced colorectal cancer; Cancer-directed surgery; Conditional survival; Outcomes; Prognosis estimate