Figure 1.
Directed acyclic graph for a proposed structural causal framework in population-based cancer research. Conditional exchangeability of the treatment effect or exposure (A) on 1-year cancer mortality (Y) is obtained through conditioning on a set of available covariates (Y1,Y0 ⊥ A|W). The minimum sufficient set, based on the backdoor criterion, is obtained through conditioning on only W1, W3, and W4. The average treatment effect for the structural framework is estimated as the average risk difference between the expected effect of the treatment conditional on W among treated persons (E(Y|A = 1; W)) and the expected effect of the treatment conditional on W among the untreated (E(Y|A = 0; W)). W1, socioeconomic status; W2, age; W3, cancer stage; W4, comorbidity.