Variation in modes of chemotherapy administration for breast carcinoma and association with hospitalization for chemotherapy-related toxicity

BACKGROUND. To the authors' knowledge, few studies to date have addressed the patterns of how chemotherapy was administered (administration modes) over time. In the current study, the goal of the authors was to describe how chemotherapy for breast carcinoma was administered and to determine whether chemotherapy administration modes were associated with toxicity in a community-based large cohort. METHODS. The authors studied 5256 women who were diagnosed with breast carcinoma at age 65 years or older between 1992-1999 and received chemotherapy. The patients were identified from the Surveillance, Epidemiology, and End Results (SEER)Program-Medicare linked databases. Chemotherapy drugs and modes of administration were determined through procedure codes in Medicare claims. RESULTS. Of the 5256 patients who received chemotherapy, 33% received it through an intravenous infusion for less than 1 hour; 39% through an intravenous infusion lasting 1-8 hours; 15% through an intravenous infusion lasting longer than 8 hours and requiring a pump; 12% through an intravenous push technique; and 1% through a subcutaneous, intramuscular, or intralesional injection. These modes varied substantially across the 11 SEER areas. The risks of hospitalization for chemotherapy-related toxicities (neutropenia, fever, thrombocytopenia, and adverse effects of systemic therapy) were not found to be significantly associated with different modes of chemotherapy after adjusting for other factors. Compared with patients receiving 5-flurouracil using an intravenous infusion for longer than 8 hours, the risk of toxicity was determined to be 0.96 (95% confidence interval [95% CI], 0.63-1.47) for patients treated with an intravenous infusion lasting 1-8 hours; 0.94 (95% CI, 0.62-1.41) for patients treated with an intravenous infusion lasting less than 1 hour; and 0.66 (95% CI, 0.38-1.08) for patients treated with subcutaneous, intramuscular, or intralesional injection or an intravenous push technique. CONCLUSIONS. There were substantial geographic variations noted in the modes of administering chemotherapy; however, these variations did not appear to be associated with the risk of toxicities (neutropenia, fever, thrombocytopenia, and adverse effects of systemic therapy).