Purpose: To determine the patterns of use of anthracycline- and taxane-based chemotherapy for breast cancer treatment.
Methods: Claims from a 5% national Medicare sample and from a nationally representative claims database (Marketscan) from 1998 to 2009 were used. Patients with International Classification of Diseases (ICD), ninth revision, codes indicating breast cancer, ICD and Common Procedural Terminology codes indicating breast surgery, and claims for chemotherapy between 3 months before and 12 months after surgery comprised the study cohort. Chemotherapy was classified as anthracycline-based or taxane-based, and the percentages of use were calculated. Piecewise regression models were used to identify the inflection points in the rates of chemotherapy use. The effect of patient characteristics on receiving different types of chemotherapy was estimated by multivariable logistic regression models.
Results: A total of 4,458 patients were included in the Medicare cohort and 30,422 in the private insurance cohort. After 2005, a sharp increase in the use of taxane-based chemotherapy and a decline in anthracycline-based chemotherapy was seen. By 2008 in the Medicare cohort, 51% of patients received taxane-based and 32% received anthracycline-based chemotherapy. By the end of 2008, the majority of patients younger than 65 years were also receiving taxane-based chemotherapy. Patients younger than 35 years were less likely to be treated with a taxane-based regimen, whereas patients who underwent 21-gene recurrence score testing and those treated with trastuzumab were more likely to receive taxane-based chemotherapy.
Conclusion: The use of anthracycline-based chemotherapy has declined, and the majority of patients with breast cancer are instead receiving taxane-based chemotherapy. The potential impact on patient outcomes is unknown.