Trastuzumab use and CNS metastasis in Medicare patients diagnosed with metastatic breast cancer (MBC).
Griffiths R., Lalla D., Brammer M., Herbert R., Doan J., Danese M.
1123 Background: While trastuzumab was approved in 1998 for treating patients with HER-2-positive MBC, there is little information on its use in the Medicare setting. METHODS: We used SEER-Medicare data to examine patterns of trastuzumab use in women diagnosed with MBC . An index date was defined as either the date of diagnosis (stage IV) or of first distant recurrence (stage 0-III). Included patients were diagnosed in 2000-2002, and had their first claim for trastuzumab between their index date and December 31, 2005, the end of the observation period. Patients were divided into those who received trastuzumab as part of their first treatment following their index date (Group A), and those who began trastuzumab after at least one course of chemotherapy (Group B). Chemotherapy agents were grouped into antimicrotubule (vinorelbine, docetaxel, paclitaxel, vincristine), anthracycline (doxorubicin, epirubicin), cyclophosphamide, other, and unknown. RESULTS: 281 patients met the inclusion criteria. Overall, the median (mean) time from the index date to initial chemotherapy and/or trastuzumab treatment was 35 (94) days (range 1-1,587 days). The average duration of trastuzumab use (first to last administration) was 371 days (median 239), during which patients averaged 2.3 trastuzumab claims per month. There were 192 (68%) patients in Group A. The median (mean) time from diagnosis to initial treatment in Group A was 34 (94) days. 64 (33%) received trastuzumab alone, and 121 (63%) received trastuzumab with an antimicrotubule. In Group B (89 patients), the median (mean) time to initial chemotherapy was 41 (92) days. 36 (40%) received anthracycline and/or cyclophosphamide based therapy, 22 (25%) received an antimicrotubule without either an anthracycline or cyclophosphamide. The median (mean) time from initial chemotherapy to initial trastuzumab therapy was 233 (368) days. At that time, 29 (33%) received trastuzumab alone, and 54 (61%) received trastuzumab plus an antimicrotubule. CONCLUSIONS: To our knowledge, this is the first study to describe patterns of trastuzumab use in Medicare. When used for metastatic breast cancer, trastuzumab was most often provided soon after diagnosis as part of initial treatment, and usually with an antimicrotubule agent. [Table: see text].