Main Session
Sep
28
PQA 04 - Breast Cancer, Patient Reported Outcomes/QoL/Survivorship, Functional Radiation Medicine, Hematologic Malignancies, Palliative Care, and International/Global Oncology
2782 - Palliative EBRT among Patients Receiving Lu-PSMA-617 for Polymetastatic Prostate Cancer: Local Control and Survival Outcomes
Presenter(s)
Emerson Lee, MD - Mass General Brigham Cancer Institute, Somerville, MA
E. E. Lee1,2, E. Adib1,2, K. Menon2, J. H. Killoran2, H. Stoltenberg3, H. Jacene4, P. Ravi3, and M. A. Huynh2; 1Harvard Radiation Oncology Program, Boston, MA, 2Department of Radiation Oncology, Brigham and Women’s Hospital / Dana-Farber Cancer Institute, Boston, MA, 3Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, 4Department of Radiology, Brigham and Women’s Hospital / Department of Imaging, Dana-Farber Cancer Institute, Boston, MA
Purpose/Objective(s):
Lu-PSMA-617 is increasingly used for patients with metastatic castration-resistant prostate cancer (mCRPC). Many patients receive external beam radiation therapy (EBRT) for purely palliative indications during the disease course. However, outcomes following palliative EBRT in this population remain poorly characterized. We describe our institutional experience with these patients and evaluated lesion-level local control (LC) and overall survival (OS) among patients who received Lu-PSMA-617 in addition to EBRT with non-ablative, palliative intent.Materials/Methods:
An institutional registry database comprising all patients receiving Lu-PSMA-617 between June 2022 and August 2025 was retrospectively analyzed to identify those treated with EBRT for purely palliative indications (e.g., pain control, neurologic compromise, or impending fracture) in the setting of advanced disease. Patient, clinical, and treatment information was abstracted from the electronic medical record. Lesion-level LC was assessed by imaging and clinical documentation. OS was calculated from time of first Lu-PSMA-617. Kaplan Meier estimates were used to estimate time-to-event outcomes.Results:
Seventy-three patients received EBRT for purely palliative indications while treated with Lu-PSMA-617. A total of 145 lesions were treated, a vast majority of which were osseous (94.5%). EBRT was delivered concurrently with Lu-PSMA-617 in 7 (4.5%) courses, within 6 months of Lu-PSMA-617 initiation or completion in 74 (51.0%) courses, and between 6-12 months of initiation or completion in 28 (16.9%) courses. At the time of palliative RT, 64.8% of courses were delivered in the setting of >10 metastases, 19.0% with 6-10 lesions, and 15.5% with 1-5 lesions. The most common indications for palliative EBRT included bone pain (110, 75.2%), cord compression or spinal neuropathy (15, 10.3%), prophylaxis for fracture and other local sequelae (15, 10.3%), and cranial neuropathy due to calvarial disease (7, 4.8%). Radiation was most frequently delivered using 3D technique (127, 87.6%); the most common regimens were 4 Gy × 5 (40.7%), 3 Gy × 10 (23.4%), and 8 Gy × 1 (15.9%). LC was assessed in 109 of these lesions, with a LC rate of 72.5% (95% CI 63.1 80.6%). Median OS among the 73 patients was 10.9 months (95% CI 8.6 15.4). Three sites (2.8%) had fractures at the treated site (all vertebral), with an overall low rate of late toxicity.Conclusion:
Among patients receiving Lu-PSMA-617 for advanced polymetastatic prostate cancer, palliative EBRT achieved durable local control using predominantly conventional fractionation, with low rates of toxicity. Even in the setting of extensive disease (>10 metastases in the majority), symptom-directed EBRT remained effective and feasible, supporting its continued integration alongside PSMA-targeted radioligand therapy.