Chemotherapy dose selection in a diverse sample of medically underserved women with breast cancer.

Abstract

221 Background: Black race, lower socioeconomic status, and obesity have been associated with reduced first cycle doses of adjuvant chemotherapy. There are no data on dosing patterns in Hispanics. The purpose of this study was to investigate chemotherapy dose selection among a diverse sample of patients treated for breast cancer through the Breast and Cervical Cancer Prevention Treatment Act (BCCPT) in the state of California from February 2003 to September 2005. Methods: Extensive medical record review of patients who received chemotherapy was performed. We calculated the first cycle dose ratio by dividing the actual doses of chemotherapy delivered by the expected doses. Expected doses were those in standard chemotherapy regimens. Bivariate and multivariate regression analyses were performed to identify clinical and non-clinical factors associated with dose reductions. Results: Among 658 patients with stages I to III breast cancer in the sample, 522 received chemotherapy. After exclusions, the final analytic sample included 403 women (122 non-Hispanic whites, 21 non-Hispanic blacks, 226 Hispanics, 28 Asians, and 6 of other races). Dose ratios < 0.9 were given to 57 patients (14%). In bivariate analyses, race/ethnicity (p=0.004), body mass index (p< 0.001), comorbidity (p< 0.001), and treatment at a non-academic site (p=0.015) were associated with a dose ratio < 0.9. Hispanics and Asians were least likely to have dose reductions. In multivariable analysis, only comorbidity (p=0.03), severe obesity (p=0.003), and being treated at a non-academic center (p=0.03) remained significantly associated with dose reductions. Race/ethnicity was no longer associated with dose selection. Conclusions: The majority of women diagnosed and treated through the BCCTP received high quality chemotherapy. Clinical factors (comorbidity and obesity) as well as site of care were associated with chemotherapy dose selection. The processes and resources in place at academic medical centers may account for the role of treatment site in quality of chemotherapy dose selection. Efforts to standardize dose selection across obesity status and treatment facilities are warranted.