OBJECTIVES:  To examine the patient characteristics, cancer therapy use, and costs among patients with mPC. METHODS: Subjects in the Marketscan Commerical Claims and Encounters and Supplemental Medicare databases (July 1, 2004 - June 30, 2008) were included if they received a diagnosis of metastastasis (ICD-9 codes: 197.x – 199.x ) on or after the first occurrence of PC (ICD-9 code: 157.x), had no claims for other secondary metastases within 6 months of the initial mPC claim (e.g. index date), and had continuous insurance coverage from 6 months prior through at least one month post index.  Outpatient cancer therapies and costs are described from mPC index until loss to follow up or end of the data collection period.     RESULTS: There were 4938 subjects with incident mPC included in the analysis.  The mean age at index date was 64.8 years (SD=11.8) and 53.8% were male.  Subjects were followed an average of 8.3 months post index.  Among patients with incident mPC, 53.3% received outpatient chemotherapy  with gemcitabine  (76.4%) being the most commonly received therapy.  20.1% of mPC subjects received the targeted agent, erlotinib, post index, with 63.6% of its use occurring in combination with gemcitabine. Subjects who received gemcitabine, received an average of 9.5 doses (SD: 8.8) over 108.9 days (SD: 129.5).  Subjects who received erlotinib, filled an average of 3.9 prescriptions (SD: 4.1) following mPC index.  Post metastases, 84.1% and 73.3% of subjects were hospitalized or visited the ER respectively .  The mean cost per month of treating mPC subjects was $16,192 (SD=$21,639), with the majority of these costs attributed to inpatient stays (57.8%) and outpatient visits (35.0%).  Outpatient cancer therapies contributed 5.3% of the mean monthly cost post index.  CONCLUSIONS: Gemcitabine was the predominant cancer therapy among subjects with incident mPC.  Outpatient cancer drugs constituted a small portion of the total mean monthly cost of mPC.