OBJECTIVES: Treatment of bone metastases secondary to prostate cancer typically involves different provider types and a combination of surgery, radiation, and pharmaceutical treatment.   This study evaluated treatment patterns and costs for patients with bone metastases secondary to prostate cancer. Which providers had patients with bone metts that increased costs in surgery, radiation and chemotherapy compared to no bone metts?  METHODS: Continuously enrolled patients in the MarketScan database between January 2004 and December 2010 with evidence of bone metastases (ICD9 code 198.5 or treatment with one of the following medications: zolderonic acid, pamidronate, or demosumab) were included.  The relationship between patterns of care regarding physician specialty, type of therapy and cost of treatment were assessed. RESULTS: Total of 4493 patients had evidence of bone metastases.  Most patients (n=2633, 59%) had both an urologist and a radiologist involved in their care.  Common combinations of providers were urologist and radiologist (U&R, 22%); urologist, radiologist, and surgeon (U, R&S, 21%), and urologist, radiologist, and oncologist (U, R&O, 17%).  A majority of patient were prescribed hormone therapy (89%) and 76% were prescribed steroid agents (mostly glucocorticoids).  Half of the population received radiation therapy (n=2274, 51%) and 1,838 (41%) received surgery related to their prostate cancer.  Significant differences in total cost, depending on the mix of specialists involved in care: U&R: $22,133; U, R&S: $28,305; and U, R&O: $34,366 (p<0.001 for all pairwise comparisons).  Common treatment combinations were also associated with significantly different total costs: patients receiving steroids, radiation, chemotherapy, and hormone treatment cost the most (mean: $47,914) while patients steroids, surgery, chemotherapy, and hormone therapy cost the least (mean: $31,612). CONCLUSIONS: Significant variation in patterns of care and total costs for patients who have bone metastases secondary to prostate cancer.   Additional studies should examine the potential drivers of this variation and strategies to maximize cost-effectiveness.