Fig. 2

Progression-Free Survival Based on Ever- (solid line) and Never-Users (dashed line) of Oral Contraceptives. In univariate analyses ever-users of oral contraceptives (n = 700) manifested a longer progression-free survival compared to never-users (dashed line) (n = 489) (HR = 0.71 (95 % CI: 0.61, 0.83); p < 0.0001 (accounting for left truncation). Within the cohort were a total of 656 events of cancer progression. Similar statistically significant findings were seen in univariate analyses when patients were dichotomized on the basis of duration of oral contraceptive use