Figure 1.

Event-free survival estimates with (A) number of subjects at risk, stratified by smoking status; and (B) number of subjects at risk, with further stratification of never smokers (passive/no passive exposure). Kaplan–Meier event-free survival plots are presented stratified by smoking status (current, former, never–no passive, and never-passive). Log-rank test of equality over smoking categories has P < 0.0001. When never smokers are further segmented, the hazards for never, no passive exposure and never, passive exposure cross over each other at several points and do not seem to be different from each other.