At the Bonferroni significance level (P < 6.83 × 10−5), the MR analysis unveiled associations between seven proteins (KDELC2, SPINT2, TNFRSF10B, GSTP1, IGF2R, CTSS, HDGF) and PCa; five proteins (CPNE1, PDIA3, GDI2, ISLR2, CTSF) and BRCa; and four proteins (SFTPB, CTSH, ICAM5, FLRT3) and LCa. Here, ISLR2 is linked to posterior cortical atrophy.