Abstract P1-09-04: Taxanes in Metastatic Breast Cancer: Claims Analysis of Neutropenia, Infections, and CSF Costs
Authors: Force RW , Pugmire BA , Culbertson VL 
Published: April 2011

Abstract
Background: The taxanes (paclitaxel {Taxol}, docetaxel {Taxotere}, and nab-paclitaxel {Abraxane}) are used in women with metastatic breast cancer (MBC). Clinical trials indicate that these drugs may differ in their toxicity profiles. Utilizing medical claims data, we evaluated the rates of neutropenia and infectious complications and costs of colony-stimulating factors (CSF) associated with taxane-based chemotherapy in MBC. Objective: To determine if differences exist in rates of neutropenia and infections in patients receiving taxane-based chemotherapy for MBC. Additionally, to compare costs associated with CSF use for neutropenia between the taxanes.
Methods: Women with MBC were identified with ICD-9-CM codes and by their prior use of adjuvant chemotherapy regimens. Paid medical claims (source: Ingenix Consulting) from May 1, 2006 to April 30, 2009 were analyzed. Study groups were defined according to the first taxane administered. Demographic and taxane utilization data were collected. We accounted for differing dosing schedules by calculating cumulative taxane exposure (CTE) based on the mean number of doses received and mean days between doses. Taxane-related neutropenia or infection was defined as ICD-9-CM codes for these adverse events within 21 days of taxane administration. Cox proportional hazards models were used to compare rates between taxanes and adjusted for age, co-morbidity using the Romano index, and prior and concurrent chemo. Total CSF costs per patient with MBC were adjusted for a variety of variables with Tobit models. Results: 4,503 women (mean age: 53 +/− 10 years) with MBC were identified: 2,599 in the docetaxel group; 1,643 received paclitaxel; and 261 received nab-paclitaxel. On average, patients in the nab-paclitaxel group received more CTE (207.9 days) than either paclitaxel (110.2 days) or docetaxel (113.1 days). Compared with docetaxel users, women receiving nab-paclitaxel (HR 0.27; 95%CI 0.20-0.37) and paclitaxel (HR 0.63; 95%CI 0.56-0.71) were significantly less like to develop neutropenia. Nab-paclitaxel users also experienced lower rates of neutropenia compared with paclitaxel users (HR 0.43; 95% CI 0.31-0.60). Infectious complications were not different between the three drugs: nab-paclitaxel compared with docetaxel (HR 1.24; 95% CI 0.83-1.88), paclitaxel compared with docetaxel (HR 0.99; 95% CI 0.75-1.31), and nab-paclitaxel compared with paclitaxel (HR 1.26; 95% CI 0.83-1.90). Over the study period, the average nab-paclitaxel patient had $12,100 less in CSF costs compared with docetaxel (P&lt;0.001); patients receiving paclitaxel incurred $9,232 less in CSF costs than those receiving docetaxel (P&lt;0.001). The difference between nab-paclitaxel and paclitaxel was also statistically significant (P&lt;0.001). Conclusions:
Compared with docetaxel and paclitaxel, patients receiving nab-paclitaxel had a higher cumulative taxane exposure, yet experienced a 73% and 57%, respectively, reduction in neutropenia rates. Patients receiving nab-paclitaxel spent significantly less on CSF than those receiving docetaxel or paclitaxel, but there was no difference in infectious complications.
Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P1-09-04.