Clinical benefit of early treatment with bone-modifying agents for preventing skeletal-related events in patients with genitourinary cancer with bone metastasis: A multi-institutional retrospective study.

OBJECTIVES: To evaluate the clinical benefit of bone-modifying agents and identify the risk factors of skeletal-related events in patients with genitourinary cancer with newly diagnosed bone metastasis. METHODS: This was a multicenter retrospective study including a total of 650 patients with bone metastasis of the following cancer types: hormone-sensitive prostate cancer (n = 443), castration-resistant prostate cancer (n = 50), renal cell carcinoma (n = 80) and urothelial carcinoma (n = 77). Clinical factors at the time of diagnosis of bone metastasis were analyzed. Early treatment with bone-modifying agents was defined as follows: administration of bone-modifying agents before the development of skeletal-related events and within 6 months from the diagnosis of bone metastasis. RESULTS: During the follow-up period (median 19.0 months, interquartile range 6.0-43.8 months), skeletal-related events were reported in 88 (20%) patients with hormone-sensitive prostate cancer, 17 (34%) patients with castration-resistant prostate cancer, 58 (73%) patients with renal cell carcinoma and 34 (44%) patients with urothelial carcinoma. Early treatment with bone-modifying agents significantly prolonged the time to the first skeletal-related event in castration-resistant prostate cancer, renal cell carcinoma and urothelial carcinoma, but not in hormone-sensitive prostate cancer. Bone pain and elevated alkaline phosphatase levels were independent predictive risk factors of the first skeletal-related event. The subgroup analysis showed that early treatment with bone-modifying agents was associated with prolonged time to the first skeletal-related events in patients with bone pain or elevated alkaline phosphatase levels. CONCLUSIONS: Early treatment with bone-modifying agents should be considered, especially for patients with bone pain and elevated alkaline phosphatase levels, to prevent skeletal-related events in patients with genitourinary cancer with bone metastasis.