title: Statistical comparison of survival models for analysis of cancer data.
abstract: BACKGROUND
  The Cox Proportional Hazard model is the most popular technique to analysis the effects of covariates on survival time but under certain circumstances parametric models may offer advantages over Cox's model. In this study we use Cox regression and alternative parametric models such as: Weibull, Exponential and Lognormal models to evaluate prognostic factors affecting survival of patients with stomach cancer. Comparisons were made to find the best model.
  
  
  METHODS
  To determine independent prognostic factors reducing survival time for stomach cancer, we compared parametric and semi-parametric methods applied to patients who registered in one cancer registry center located in southern Iran using the Akaike Information Criterion.
  
  
  RESULTS
  Of a total of 442 patients, 266 (60.2%) died. The results of data analysis using Cox and parametric models were approximately similar. Patients with ages 60-75 and >75 years at diagnosis had an increased risk for death followed by those with poor differentiated grade and presence of distant metastasis (P<0.05).
  
  
  CONCLUSIONS
  Although the Hazard Ratios in the Cox model and parametric ones are approximately similar, according to Akaike Information Criterion, the Weibull and Exponential models are the most favorable for survival analysis.
authors.affiliation: Research Center for Gastroenterology and Liver Diseases, Shaheed Beheshti University MC, Tehran, Iran. b_moghimi_de@ yahoo.com
authors.forename: Bijan
authors.initials: B
authors.lastname: Moghimi-Dehkordi
authors.forename: Azadeh
authors.initials: A
authors.lastname: Safaee
authors.forename: Mohamad Amin
authors.initials: MA
authors.lastname: Pourhoseingholi
authors.forename: Reza
authors.initials: R
authors.lastname: Fatemi
authors.forename: Ziaoddin
authors.initials: Z
authors.lastname: Tabeie
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Zali
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D007492:Iran; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D009361:Neoplasm Invasiveness / Q000473:pathology*; D009367:Neoplasm Staging; D011379:Prognosis; D012042:Registries; D012044:Regression Analysis; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013274:Stomach Neoplasms / Q000401:mortality* / Q000473:pathology* / Q000628:therapy; D016019:Survival Analysis