Although the patient’s PSA was reduced from 2.8 ng/mL to 1.0 ng/mL while on combined ADT and enzalutamide, increasing pelvic pain prompted repeat imaging which revealed an increase in the size of the right external iliac lymph node metastasis from 54.9 mm at baseline to 75.2 mm (maximal axis dimension; Figure 1B,C). Here, KLK3 is linked to metastatic malignant neoplasm in the lymph nodes.