The Effect of Bone-Modifying Agents on Post-Bone Metastasis Survival

Background: Bone metastasis is associated with a poor prognosis. Bone-modifying agents (BMA) are commonly used for the prevention or treatment of skeletal-related events (SRE) in patients with bone metastasis; however, whether or not treatment with BMA improves survival remains unclear. In this study, we investigated whether BMA was involved in post-bone metastasis survival. Methods: A total of 539 cancer patients were retrospectively analyzed to identify significant in-dependent factors in post-bone metastasis survival. Results: Among the overall population, patients with the following cancers had a median survival longer than 24 months: thyroid, 97.2 months; breast, 51.5 months; prostate, 47.2 months; and kidney, 38.8 months. Treatment with BMA was a significant positive prognostic factor: BMA (-) n = 203, median post-bone metastasis survival 7.8 months (95% CI: 5.8–12.5); BMA (+) n = 336, median post-bone metastasis survival 21.9 months (95% CI: 16.1–26.4) (p < 0.001). This was particularly evident in gastrointestinal (GI) cancer (hazard ratio [HR]: 0.62, 95% CI: 0.40–0.95; p < 0.05), and non-small cell lung cancer (NSCLC) without the epidermal growth factor receptor (EGFR) mutation (HR: 0.56, 95% CI: 0.34–0.91) (p < 0.05). Con-clusions: Treatment with BMA is recommended not only for the prevention and/or treatment of SRE, but also to improve survival, particularly in cancers with typically poor post-bone metastasis sur-vival such as GI cancer and NSCLC without the EGFR mutation.