title: Estimation of hazard function and its associated factors in gastric cancer patients using wavelet and kernel smoothing methods.
abstract: OBJECTIVE
  Increase of mortality rates of gastric cancer in Iran and the world in recent years reveal necessity of studies on this disease. Here, hazard function for gastric cancer patients was estimated using Wavelet and Kernel methods and some related factors were assessed.
  
  
  METHODS
  Ninety- five gastric cancer patients in Fayazbakhsh Hospital between 1996 and 2003 were studied. The effects of age of patients, gender, stage of disease and treatment method on patient's lifetime were assessed. For data analyses, survival analyses using Wavelet method and Log-rank test in R software were used.
  
  
  RESULTS
  Nearly 25.3% of patients were female. Fourteen percent had surgery treatment and the rest had treatment without surgery. Three fourths died and the rest were censored. Almost 9.5% of patients were in early stages of the disease, 53.7% in locally advance stage and 36.8% in metastatic stage. Hazard function estimation with the wavelet method showed significant difference for stages of disease (P<0.001) and did not reveal any significant difference for age, gender and treatment method.
  
  
  CONCLUSIONS
  Only stage of disease had effects on hazard and most patients were diagnosed in late stages of disease, which is possibly one of the most reasons for high hazard rate and low survival. Therefore, it seems to be necessary a public education about symptoms of disease by media and regular tests and screening for early diagnosis.
authors: Department of Mathematics and Statistics, School of Health Management and Information Sciences, Hospital Management Research Center, Tehran University of Medical Sciences, Tehran, Iran.
authors: Azadeh
authors: A
authors: Ahmadi
authors: Masoud
authors: M
authors: Roudbari
authors: Mahmood Reza
authors: MR
authors: Gohari
authors: Bistoon
authors: B
authors: Hosseini
mesh_terms: D000368:Aged; D000465:Algorithms; D005260:Female; D006801:Humans; D007492:Iran / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D025341:Principal Component Analysis; D011379:Prognosis; D016016:Proportional Hazards Models; D013274:Stomach Neoplasms / Q000453:epidemiology / Q000401:mortality* / Q000473:pathology; D015996:Survival Rate; D058067:Wavelet Analysis