The significant increase in MCT4 observed in high-grade PCa TSCs is also consistent with prior publications indicating that high MCT4 expression predicts aggressive disease in many cancers [43], and specifically in PCa, where it has been shown to correlate with high-grade cancer (Gleason ≥ 7) and other clinical characteristics associated with poor prognoses, such as higher serum PSA levels at diagnosis and extension of cancer through the prostatic capsule [29,30,44]. This evidence concerns the gene KLK3 and cancer.