KLK3 and pachyonychia congenita: Figure 3B demonstrates the effect of changes in PSA slope on disease-free survival using Kaplan–Meier analysis. The change in PSA slope (as a dichotomized variable) was significantly prognostic for disease-free survival (log rank test, p < 0.001) therefore the third criterion of Prentice was met. But the Mann–Whitney Test for slope by recurrence events shows that the mean-ranks of slope is not different in two groups with or without PC recurrence (p = 0.345).