Off-label drug use in women with breast cancer

Abstract

1016 Background: Despite reports of widespread use of off-label agents in cancer treatment, little is known about the off-label use of agents in the treatment of breast cancer patients. Methods: We used data from the Surveillance, Epidemiology, and End Results (SEER) - Medicare linked database to identify 2082 persons older than 65 years who were diagnosed with distant stage breast cancer between 1991 and 2002 and who were treated with chemotherapy between diagnosis and death. Off versus on-label classification was based upon FDA-approved indication in the treatment of breast cancer. We calculated the percentage of patients receiving off-label chemotherapy and used multivariate logistic regression models to estimate predictors of off-label chemotherapy use. We also evaluated the appropriateness of off-label chemotherapy drugs using DRUGDEX classifications. Results: Overall, 34.9% of patients were treated with off-label chemotherapy drugs. Of the thirty-six agents that were used to treat these patients, only 8 (22%) were FDA-approved for use in the treatment of breast cancer. Off-label use was least common in patients age 80 years and older (OR 1.93, 95% 1.35–2.76 for 80+ vs. 66–70 years) and varied by diagnosis year and geographic region. The most commonly used off-label agents were vinorelbine and gemcitabine, with 16.0% and 8.4% of patients receiving these agents, respectively. While 71% of the drugs used off-label lacked supporting evidence for their use in the treatment of breast cancer, these drugs were used in a small number of patients. Only 6.7% of patients were treated with drugs considered inappropriate for use in the treatment of breast cancer. Conclusions: Off-label chemotherapy use is widespread among patients with metastatic breast cancer. However, the majority of patients who received off-label chemotherapy received drugs with scientific data supporting such use. No significant financial relationships to disclose.