Proportion and Prognosis of Bone Metastases from Gastric Cancer in SEER database

Abstract Purpose The purpose of this study was to analyze the proportion and prognosis of bone metastases at diagnosis of gastric cancer using population-based data from SEER. Patients and methods Patients with gastric cancer and bone metastases (GCBM) at the time of diagnosis in advanced gastric cancer were identified using the Surveillance, Epidemiology and End Result (SEER) database of the National Cancer Institute. Multivariable logistic and Cox regression were performed to identify predictors of the presence of GCBM at diagnosis and factors associated with all-cause mortality and gastric cancer-specific mortality. Survival curves were obtained according to the Kaplan-Meier method and compared using the log-rank test. Results We identified 975 patients with gastric cancer and bone metastases at the time of diagnosis, representing 5.31% of the entire cohort and 13.35% of the subset with metastatic disease to any distant site. Among entire cohort, multivariable logistic regression identified five factors (lower age, diffused-type, adverse pathology grade, N1 staging and presence of more extraosseous metastases to liver, lung and brain.) as positive predictors of the presence of bone metastases at diagnosis. Median survival among the entire cohort with GCBM was 4.0 months (interquartile range: 1.0-8.0mo). Multivariable Cox model in SEER cohort confirmed two factors (non-cardia stomach and absence of chemotherapy) as negative predictors for overall survival. We also found poor survival in non-surgical patients using Fine and Gray’s competing risk regression model. Conclusion The findings of this study provided population-based estimates of the proportion and prognosis for GCBM at time of diagnosis. These findings provided guidance for screening and treatment of GCBM patients. Chemotherapy may make benefit for overall survival, but the role of surgery remained to be determined by further research.