156 Background: A prior SEER-Medicare analysis (2001-2008 data) of injectable treatment (tx) after MBC diagnosis (dx) found fulvestrant was the most common 1st-line received (15% of patients) and vinorelbine the most common 2nd- and 3rd-line tx (17% and 13%, respectively). Lifetime cost of treating MBC averaged $110,000. The current study updates this analysis and focuses on a subgroup with prescription drug (Part D) Medicare coverage to evaluate tx patterns and costs including oral agents. Methods: Sample included women with breast cancer dx 2001-2007 with concurrent or subsequent MBC dx, Medicare enrollment from 12 mo prior to dx through 2009 or death, and indication of pharmacologic MBC tx. Subgroup with part D coverage and MBC diagnosis in 2007 was identified. Lines of tx were designated as: 1st-line if 1st agent (or combination if on same day) after dx of MBC; new agents administered > 42 days after the previous agent are a new line, as well as an agent administered > 60 days after last dose of the same agent. Costs were adjusted for length of follow-up. Results: Tx patterns in the overall sample were similar to prior results. Fulvestrant remained the most common 1st-line tx (19% of patients), and vinorelbine the most common 2nd- (18%) and 3rd-line tx (16%). Total costs ($127,000) were higher than in prior study. In the subgroup with Part D coverage (Table) use of oral agents was common for all tx lines. Mean lifetime treatment costs were lower than in overall sample ($102,000) and varied by treatment received. Conclusions: In this population, oral agents are common MBC tx. Inclusion of Part D claims provides a more complete picture of tx patterns in MBC. [Table: see text]