The Influence of Gleason score ≤6 histology on the outcome of high-risk localized prostate cancer after modern radiotherapy

Background: We aimed to retrospectively review outcomes in patients with high-risk prostate cancer and a Gleason score ≤ 6 following modern radiotherapy. Materials: and Methods We analyzed the outcomes of 1,374 patients who had undergone modern radiotherapy, comprising a high-risk low grade [HRLG] group (Gleason score ≤ 6; n = 99) and a high-risk high grade [HRHG] group (Gleason score ≥ 7, n = 1,275). We included 955 patients who received brachytherapy with or without external beam radio-therapy (EBRT) and 419 who received modern EBRT (intensity modulated radiotherapy [IMRT] or stereotactic body radiotherapy [SBRT]). Results: At a median follow-up of 61 (2–177) months, actuarial 5-year biochemical failure-free survival rates were 95.6% and 90.9% (p = 0.0244), respectively. The HRLG group showed fewer clinical failure frequencies than the HRHG group (0% vs 4.9%, p = 0.04) and a better 5-year distant metastasis-free survival rate than the HRHG group (100% vs 96.4%, p = 0.039). Conclusions: As the HRLG group exhibited no clinical failure and better outcomes than the HRHG group, the HRLG group might potentially be classified as a lower-risk group.