Analysis of Prognostic Factors in Gastric Cancer Using Additive Hazards Regression Models

Gastric cancer (GC) is the fourth most common cancer and the second leading cause of cancer-related death in the world. A 2005 analysis of the global incidence and cancer-related mortality revealed that 934,000 new cases of GC were diagnosed and approximately 700,000 patients died from this disease in 2002 (Parkin et al., 2005). Approximately 60% of all cases occur in developing countries with the highest rate in eastern Asia (Jemal et al., 2006). Although its incidence has been decreasing in the West for the last 20–30 years, incidence of GC has remained high in some Eastern countries (e.g., China, Korea, and Japan) (Chen et al., 2008; Yang, 2006). In Iran, the incidence is around 7300 cases per year, which is the most common cancer in men. Mortality from GC is also the first cause of death due to cancer in both sexes in Iran (Movahedi et al., 2009). Given to the low rate of 5-year survival of patients with GC, identification and control of risk factors remain the most effective means of prevention (Gonzalez et al., 2002). In survival analysis major interests are to compare the failure time distribution function or to assess covariate 1Department of Biostatistics, Faculty of Medical Science, Tarbiat Modares University, 2Islamic Azad University, South Tehran Branch, 3Research Center for Gastroenterology and Liver Disease, Shahid Beheshti University of Medical Sciences, Tehran, Iran *For correspondence: [email protected] Abstract