Omitting Elective Pelvic Nodes Irradiation in High Risk Prostate Cancer: Report on 43 Consecutive Elderly Patients

Background: Radiotherapy (RT) combined with androgen deprivation therapy (ADT) is a standard treatment for non-metastatic high-risk (HR) prostate cancer (PC). However, the benefit of elective nodal irradiation (ENI) in clinically node-negative (cN0) patients, although suggested, remains controversial, particularly in the elderly. We report the outcomes of elderly HR PC patients treated with prostate-only RT (PORT) and ADT in a "real-word" setting. Methods: Between 2016 and 2022, 43 consecutive elderly patients (median age 76 years) with HR- or very HR-PC according to NCCN criteria version 1.2026 (cN0, cT3-cT4 and/or ISUP Grade Group 4-5 and/or PSA serum levels at diagnosis ≥ 20 ng/mL) were treated at our institution. All patients were staged with abdominal MRI or CT and bone scan; nineteen patients (44.2%) also underwent 68Ga-PSMA-11 or 18F-fluorocholine PET/CT. All patients received PORT (predominantly moderate hypofractionation, 67.5-70 Gy in 25-28 fractions) and ADT (median duration 24 months). To ensure consistency, all oncological endpoints-Biochemical Failure-Free Survival (BFFS; Phoenix criteria), Disease-Free Survival (DFS), Metastasis-Free Survival (MFS), Prostate Cancer-Specific Survival (PCSS), and Overall Survival (OS)-were calculated from a unified time-zero (initiation of first oncological treatment). DFS was defined as a composite endpoint including biochemical failure, radiological recurrence, or initiation of salvage therapy. Results: at a median follow-up of 60 months, no patient reached the Phoenix threshold, resulting in a 100% 5- and 7-year BFFS. However, 4 patients (9.3%) experienced radiological recurrence detected via PET/CT before reaching the nadir + 2 threshold, yielding an estimated 5-year and 7-year DFS of 94.7% and 71.8%, respectively. The 5- and 7-year MFS was of 97.6% and 88.7%, respectively. Seven deaths occurred, all non-PC related, resulting in a 5-year OS of 86.7% and a Prostate Cancer-Specific Survival of 100%. Gastrointestinal toxicity was notably low (no acute or late G3-G4 events). Conclusions: Our findings suggest that PORT, when combined with long-term ADT and modern staging, provides excellent disease control and a favorable safety profile in elderly HR PC patients. Given the high rate of competing mortality in this population, treatment de-escalation via PORT appears to be a clinically reasonable strategy. These results are hypothesis-generating and warrant validation in prospective randomized trials.