PRL and prostate cancer: Steroid hormone biosynthesis, ovarian steroidogenesis, prostate cancer, citrate cycle (TCA cycle), glyoxylate and dicarboxylate metabolism, endocrine resistance, prolactin signaling pathway, tyrosine metabolism, butanoate metabolism, and dopaminergic synapse were screened out as the metabolic pathways between the two groups in the serum (Figure 7b).