Identifying Factors Affecting Cancer-related Death in Patients with Adenocarcinoma Gastric Cancer; An Analysis in the Presence of Competing Risks

Background: Adenocarcinoma is the most common type of gastric cancer that has shorter survival than other types of gastric cancer. The death of patients with this type of cancer may be due to the progression of cancer or other related causes. Objectives: The aim of this study is to determine the factors affecting death due to the cancer progression in gastric cancer patients with the diagnosis of adenocarcinoma, using competing risk models. Methods: This retrospective cohort study was performed on 306 gastric cancer patients diagnosed with adenocarcinoma referring to Imam Khomeini clinic in Hamadan from 2002 to 2017. Death due to the cancer progression was considered an interest event and death due to without progression as a competing event. To determine the effect of covariates on hazard, the cause-specific and subdistribution hazard regression models were used. Data analysis was performed, using R3.6.1 software and cmprsk and survival packages. Results: The mean (SD) age of patients was 62.3 (12.5) years and 74.3% were male. The effect of the stage, the number of involved lymphomas, and the type of treatment were significant on the hazard of death due to the disease progression in both cause-specific and subdistribution hazard models. Conclusions: The results showed that most deaths occur in the first 3 years of follow-up. The higher stage and higher number of lymph nodes have increased the hazard of death but supplementary treatment significantly decreased the hazard of death due to cancer progression in adenocarcinoma gastric cancer patients in both competing risk models.