Beyond that, a significant association between obesity and PCa progression has been established, especially in relation to more malignant and biochemical recurrence (biochemical recurrence defined as patients without postoperative endocrine therapy and radiotherapy, with two consecutive prostate-specific antigen (PSA) ≥ 0.2 μg/L during follow-up) of PCa [31,32,33]. Here, KLK3 is linked to obesity due to melanocortin 4 receptor deficiency.