Statistical Analysis:
Descriptive statistics were used to summarize patient, tumor and treatment characteristics as well as outcomes. A summary marginalization score combined scores from the three marginalization domains considered in this analysis (material deprivation, residential instability and ethnic concentration). Patients were stratified by marginalization quintiles and their characteristics were compared using the chi-square test for categorical and ordinal data or Wilcoxon rank sum test for continuous data.
The primary outcome was defined as overall survival from the date of endometrial cancer diagnosis to the date of death, as recorded in the Registered Persons Database. Survival was estimated using the Kaplan-Meier method and compared across groups using the log-rank test. Cox regression methods were used to assess factors associated with survival in the study population after verification of the proportional hazards assumption. Variables incorporated in the analyses included patient factors, such as age, comorbidity score, obesity, income and rurality, as well as marginalization indices; and disease factors, such as histology, stage, and previous history of cancer. Confidence intervals were constructed for statistics of interest. All tests and confidence intervals were two-sided and defined at the α=0.05 level of significance. All analyses were performed using SAS version 9.2 (SAS Institute, Cary, NC) and R (www.r-project.org).