CST3 and breast cancer: The PGS for serum cystatin C levels was associated with longer disease-free survival (T3: HR = 0.82, 95% CI = 0.71–0.95), breast event-free survival (T3: HR = 0.74, 95% CI = 0.61–0.91), and breast cancer–specific survival (T3: HR = 0.72, 95% CI = 0.54–0.95; Fig. 2B).