title: Prognostic Factors for Survival in Patients with Gastric Cancer using a Random Survival Forest
abstract: Background: Gastric cancer is the fifth most common cancer and the third top cause of cancer related death with
  about 1 million new cases and 700,000 deaths in 2012. The aim of this investigation was to identify important factors for
  outcome using a random survival forest (RSF) approach. Materials and Methods: Data were collected from 128 gastric
  cancer patients through a historical cohort study in Hamedan-Iran from 2007 to 2013. The event under consideration was
  death due to gastric cancer. The random survival forest model in R software was applied to determine the key factors
  affecting survival. Four split criteria were used to determine importance of the variables in the model including log-rank,
  conversation?? of events, log-rank score, and randomization. Efficiency of the model was confirmed in terms of Harrell’s
  concordance index. Results: The mean age of diagnosis was 63 ±12.57 and mean and median survival times were 15.2
  (95%CI: 13.3, 17.0) and 12.3 (95%CI: 11.0, 13.4) months, respectively. The one-year, two-year, and three-year rates
  for survival were 51%, 13%, and 5%, respectively. Each RSF approach showed a slightly different ranking order. Very
  important covariates in nearly all the 4 RSF approaches were metastatic status, age at diagnosis and tumor size. The
  performance of each RSF approach was in the range of 0.29-0.32 and the best error rate was obtained by the log-rank
  splitting rule; second, third, and fourth ranks were log-rank score, conservation of events, and the random splitting
  rule, respectively. Conclusion: Low survival rate of gastric cancer patients is an indication of absence of a screening
  program for early diagnosis of the disease. Timely diagnosis in early phases increases survival and decreases mortality.
authors.affiliation: Department of Public Health, School of Public Health, Ardabil University of Medical Sciences, Ardabil, Iran. Email: Abazari.malek@gmail.com
authors.forename: Davoud
authors.initials: D
authors.lastname: Adham
authors.forename: Nategh
authors.initials: N
authors.lastname: Abbasgholizadeh
authors.forename: Malek
authors.initials: M
authors.lastname: Abazari
keywords: Gastric cancer; random survival forest; Hamadan; Iran