KLK3 and neoplasm: Figure S1A–C shows representative images of PITX1 immunostaining in tumor samples with a negative, low, and high PITX1 level. A total of 4% of the tumor samples (n = 600) showed a high PITX1 level, 57.7% (n = 8,661) were classified as low and 38.3% (n = 5749) as negative (Table 3). A Kaplan–Meier analysis revealed that patients with a high PITX1 level had distinctive lower PSA-recurrence free survival compared to patients with a low or negative PITX1 level (p-value < 0.0001) (Figure 4A).