High-Intensity Focused Ultrasound (HIFU) therapy for localized prostate cancer is most commonly indicated and successful for patients presenting with a Gleason score of 6 or 3+4=7 (Intermediate Grade Group 1 or 2). While select specialized centers evaluate patients with favorable Gleason 8 (4+4) tumors under strict clinical trial parameters, high-risk cancers characterized by extensive Gleason 9 or 10 scores typically require whole-gland multi-modal treatments like radical surgery or systemic radiation combined with hormone therapy rather than focal ablation approaches.