CMF-regimen preferred as first-course chemotherapy for older and sicker women with breast cancer: Findings from a SEER-Medicare-based population study.

OBJECTIVE: The objective of this study was to determine the sociodemographic and clinical characteristics associated with Cyclophosphamide, Methotrexate, and 5-Fluorouracil (CMF) utilization as a first-course chemotherapy regimen among female Medicare patients with early-stage breast cancer.
METHODS: A longitudinal study was conducted with women 66 years and older, diagnosed with stage I to III breast cancer from 1993 to 2004, and receiving chemotherapy using the Surveillance, Epidemiology, and End Result-Medicare data. First-course CMF chemotherapy was defined as chemotherapy initiation within 6 months of breast cancer diagnosis, with at least 1 claim of CMF each within 1 year of diagnosis. Logistic regression was used to perform the analysis.
RESULTS: Older and sicker women, living in census tracts with lower average education, and diagnosed with advanced stage, hormone receptor-negative tumors have a higher probability of CMF administration. Receipt of lymph node dissection and nonreceipt of radiation therapy were also associated with CMF administration. CMF administration has declined over the years and has significant regional variation.
CONCLUSIONS: Reduction in CMF use overtime indicates the increased use of newer and more effective systemic therapies among breast cancer patients. In spite of the reduction in CMF use over time, CMF is more frequently administered to older and sicker women, possibly because of higher risk of anthracycline-induced toxicities in these patients. Clinical guidelines have no recommendations for CMF administration in breast cancer patients with certain clinical characteristics. Hence, it is important to understand if the associations observed in this study can be clinically justified in order to reduce unjustified use of less-effective regimens.