ISH and immunohistochemistry (ICH) demonstrated that circFGFR1int2 and FGFR1 protein were overexpressed in PCa, and the positive rate of circFGFR1int2 in PCa was significantly higher than in BPH (P < 0.0001) (Fig. 1E). Here, FGFR1 is linked to posterior cortical atrophy.