Relative Survival, Conditional Survival, and Causes of Death in Patients with Early Gastric Cancer, with a Focus on Differences Between Cardia and Non-Cardia Cancer

<b>Background</b>: Many researchers believe that cardia (CGC) and non-cardia (NCGC) are two different types of tumors, having different features like incidence rate, risk factors, geographical location, and socioeconomic status. This study aims to investigate the causes of death (COD) survival rates among early gastric cancer patients with a focus on differences between CGC and NCGC. <b>Methods</b>: This retrospective study employed SEER*stat software (version 8.3.92) to analyze the SEER 17 plus dataset (2000-2019). Standardized mortality ratios (SMR) were computed. Relative survival and conditional survival post-diagnosis were calculated using R software (version 4.1.0) among the different subgroups. <b>Results</b>: Within the follow-up period, 55.4% (5381) died, predominantly within the initial year post-diagnosis. Esophageal cancer was the leading non-gastric cancer cause in CGC, while miscellaneous tumors dominated in NCGC. The 1-year and 5-year relative survival for CGC patients were 76.4% and 48.9% respectively, while for NCGC were 80.4% and 63.9%. The 3-year conditional survival after 1 year and 5e years of survival for CGC were 68.7% and 88.8%, respectively, while for NCGC were 82.2% and 93.5%, respectively. This means that the longer a person has survived after diagnosis with cancer, the greater the likelihood that person will survive for another 3 years. <b>Conclusions</b>: This study sheds light on the substantial impact of non-cancer COD in GC patients, underscoring the necessity of considering comorbidities in their comprehensive management and follow-up. <b>Impact</b>: This study contributes valuable insights for clinical decision-making and informs future research directions regarding CGC and NCGC.