Radiotherapy for Bone Metastases in Patients With Excellent Performance Status: Patterns of Care and Prognostic Factors for Survival.

Background/aim: The aim was to analyze patterns of care, e.g., fractionation of radiotherapy and treatment completion, and prognostic factors for survival in patients irradiated for bone metastases who had excellent Eastern Cooperative Oncology Group (ECOG) performance status (PS), defined as ECOG PS 0.

Patients and methods: A retrospective analysis was performed (2010-2024, n=1,244 radiotherapy courses) that included patients with bone metastases treated with conventional palliative or stereotactic single- or multi-fraction regimens (SBRT).

Results: Patients with ECOG PS 0 (n=129, 10%) had 0% 30-day mortality, 99% 3-months survival, and 83% 12-months survival. Only three of 129 (2%) did not complete radiotherapy. Most patients had prostate or breast cancer with bone-only metastases. In restricted analysis without inclusion of blood test results, five significant predictors of unfavorable survival emerged: steroid medication, no continuation of systemic therapy, progressive disease outside of the irradiated target volume(s), adrenal gland metastasis, and prescription of fewer radiotherapy fractions. With blood tests included, the final multivariate model suggested that survival varied with lactate dehydrogenase (strata: normal/elevated), adrenal gland metastases (yes/no), progressive disease outside of the irradiated target volume(s) (yes/no), and fraction number (>10/≤10).

Conclusion: Many patients with ECOG PS 0 experience long-term survival, influenced by disease behavior and choice of fractionation, among others. The impact of fractionation was due to imbalances in baseline characteristics, e.g., proportion of patients with de novo hormone-sensitive prostate cancer with low-volume disease receiving fractionated radiotherapy to both prostate and bone metastases. No clear impact of equivalent radiation dose in 2-Gy fractions on survival emerged.