Strengths and Limitations
This is a robust population-based study, evaluating a large sample of patients and a broad spectrum of socio-demographic, clinical and pathological information through administrative databases that have been previously validated for healthcare research. The focus on endometrial cancer in a public healthcare system mitigates some common confounders in population studies on cancer care disparities. Finally, the use of validated Canadian measures of marginalization 35provides a unique opportunity to evaluate associations between inherently complex social, educational, financial and cultural barriers and cancer outcomes.
However, there are limitations to this study design which should be acknowledged. Many exposure variables, including marginalization indices, are based on neighborhood or community characteristics, which may create misclassification bias when assessing individual patients. Moreover, stage information and Charlson scores were missing in a large proportion of the women, though missing information was evenly distributed between marginalization quintiles. We were not able to conduct an analysis of recurrence rates and cancer-specific survival because recurrence are not captured in the Ontario cancer registry and because secondary causes of death are not reliably documented in death certificates. Although overall survival is considered an important and reproducible outcome in oncology, competing causes of death may confound the interpretation of this endpoint, especially in the endometrial cancer patient population 48,49. Lastly, the association between marginalization and survival is confounded by other factors associated with SDH, including adverse health behaviors, stress, and chronic diseases and their sequelae, which we were not able to control for.