Patient Characteristics and Patterns of Therapy Use among Patients Newly Diagnosed with Early Breast Cancer: Results from a US Claims Data Analysis.
Authors: E. Pelletier, D. Smith, S. Kaura, S. Zelt, D. Battleman
Journal: Cancer Research (2009)

Abstract Background: Following a diagnosis of early breast cancer (BC), there are a variety of treatment options open to physicians. However, with the development of alternative therapies and rapidly changing clinical guidelines, there are limited data available evaluating current patterns of care. This study investigated current treatment patterns following an initial diagnosis of early BC and examined demographic and clinical differences among patients receiving tamoxifen versus aromatase inhibitors (AI) as a preliminary analysis to inform a more in-depth study assessing early BC recurrence rates between therapy groups.Methods: In a retrospective cohort analysis among enrollees in managed care health plans, we identified female patients aged 55 years or older from 2004 to 2008 who were newly diagnosed with BC and had no evidence of prior BC surgery, chemotherapy, radiotherapy, or hormone therapy. Patients were followed from the date of first BC diagnosis until evidence of first (“index”) treatment with tamoxifen or an AI (anastrozole or letrozole). Outcomes of interest included differences between hormone therapy cohorts in patient characteristics (age, payer type) and clinical characteristics (risk group, Charlson comorbidity index [CCI]). Risk group was defined by treatments identified between the time of first BC diagnosis and index hormone therapy and included low (surgery only), medium (surgery and radiotherapy), higher (surgery then chemotherapy), and highest (neoadjuvant chemotherapy or combination surgery, radiotherapy, and chemotherapy). Unadjusted comparisons between cohorts were performed, with a p-value &amp;lt;0.05 considered statistically significant.Results: Of 4,191 newly diagnosed early BC patients identified, 950 (22.7%) received tamoxifen as first hormone therapy while 3,241 (77.3%) had evidence of AI therapy. There were no significant differences between therapy cohorts for geographic region or payer type, while differences in health plan type were marginally significant (p=0.05). Mean (median) age was 60.7 (59) years for tamoxifen patients and 61.4 (60) years for AI patients (p&amp;lt;0.001). Almost 60% of patients on AI therapy had 3 or more comorbidities as defined by the CCI compared to 45% of tamoxifen patients (p&amp;lt;0.001). Differences in the proportion of hormone therapy patients by risk group are provided in Table 1; compared to tamoxifen patients, a larger proportion of patients receiving AI therapy were found to be in the higher or highest risk groups (34.9% vs. 17.1%, p&amp;lt;0.001).Conclusion: According to real-world data, it appears that upfront AI therapy is the most widely used treatment option for early BC patients, regardless of risk group. The results indicate a tendency to use AI therapy significantly more often in patients defined as higher or highest risk. These baseline data are crucial in informing the design and statistical analyses of the next phase of this study to evaluate rates of early BC recurrence between therapy cohorts.Table 1. Hormone Therapy Patients by Risk Group.Risk GroupTamoxifen (N=950)AI Therapy (N=3,241)P-valueLow339 (35.7%)920 (28.4%)p=0.001Medium449 (47.3%)1,190 (36.7%) Higher57 (6.0%)416 (12.8%) Highest105 (11.0%)715 (22.1%) Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2060.