The primary statistical analysis of efficacy was
the comparison, after three years of follow-up, of
disease-free survival between groups according to
the intention-to-treat principle, with the use of a
two-sided log-rank test stratified according to baseline
disease stage. Hazard ratios and 95 percent confidence
intervals were calculated with the use of the
Cox proportional-hazards model. Survival curves
were drawn according to Kaplan–Meier methods.