Purpose: Various models have tested the approach of risk scores in the assessment of adjuvant chemotherapy in breast cancer patients post surgery. These models are generally based on cohorts and thus have mixed results regarding the influence of adherence to recommendations of when and how to use these tests to outcomes. A microsimulation modeling approach allows the individuals characteristics of a population to be considered. In order to test such a model in a real-world population, information is needed on actual treatments and costs. We extracted this information from a cohort of breast cancer patient to apply to a microsimulation model to assess risk of disease reoccurrence and benefit of adjuvant chemotherapy in early stage breast cancer.
Methods :A cohort of early breast cancer patients was identified at the Huntsman Cancer Institute (HCI) based on ICD-9 code (174.0-174.9) and inclusion in the HCI tumor registry for invasive breast cancer from 2005-2010. Patients were included with stage I to IIIa disease at diagnosis, documented curative intent surgery, use of endocrine therapy, and lack of HER2 directed therapies (assumed as estrogen receptor positive and HER2 negative). Patients receiving adjuvant chemotherapy were identified. Price for chemotherapy was based on average wholesale price (AWP) for doxorubicin and cyclophosphamide followed by paclitaxel.
Results: A total of 367 patients with early stage breast cancer were identified with a mean age of 58.2 years. Stage I, II and IIIa comprised 55%, 37.3% and 7.7% of patients at the time of diagnosis. There were 123 patients (33.5%) treated with adjuvant chemotherapy. Among the 123 patients treated with chemotherapy, 21%, 64.2% and 14.6% were stage I, II and IIIa respectively; which comprised 12.3%, 57.7%, and 64.3% of all stage I, II, and IIIa patients, respectively. The predominate chemotherapy regimen was doxorubicin and cyclophosphamide with or without paclitaxel for 72% of patients. The AWP of this regimen is $4476 with and $1507 without paclitaxel; Oncotype Dx at AWP is $4175. The mean age in patients receiving chemotherapy was 50.6 years compared to 62.1 years in patients not receiving chemotherapy (p < 0.0001).
Conclusions: Extraction of preliminary data from a real-world breast cancer cohort provided reference data on treatments and costs for the model to assess the impact of risk scores using Adjuvant Online! and Oncotype Dx.
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