“…Even though this is the norm, certain patients have been noted to develop metastatic CaP at low PSAs. PSAs as low as 0.02ng/ml have been recorded in such patients and they are noted to have undifferentiated and very aggressive disease [24,25,26] Iwamoto and colleagues [27] in their study from 2000-2014 on 1873 patients had concluded that PSA is a useful biomarker for predicting prognosis at levels between 20 and 70 ng/ml. While Gleason's score is the single most important predictor of prostate cancer prognosis, the new grading system, known as the Grade Grouping System, better classifies CaP [28].…”