Abstract P3-06-09: Survival among patients with hormone receptor positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-) advanced breast cancer: A real-world observational study
Authors: Engel-Nitz NM , Hao Y , Gomez Rey G , Sullivan J , Willemann Rogerio J 
Published: August 2014

Background: Little is known about real-world outcomes for patients with HR+/HER2- advanced breast cancer. This study examined mortality outcomes, and in particular variations across patients with different stages of cancer and different sequencing of endocrine and chemotherapy treatments.

Methods: This retrospective study linked medical and pharmacy claims (2008-2012) from a large national US health plan with a proprietary clinical cancer database containing physician-reported clinical data on patients with breast cancer. Patients included in the study had HR+ and HER2- status, and had stage III (S3) or IV (S4) cancer at initial diagnosis, or had developed metastases following initial diagnosis (MET). The first date of diagnosis of advanced cancer or the first date of metastases following initial diagnosis was designated as the index date. Health plan enrollment for 3 months pre- and ≥12-months post- index date was required; patients who died within 12 months after index date and were continuously enrolled in the health plan were retained. A 3-month baseline period assessed prior treatment; a variable follow-up (until disenrollment or 31 Oct 2012) assessed patterns of endocrine and chemotherapy treatments following the index date. Patient mortality was identified via a combination of Social Security mortality data and patient hospital discharge status from claims data. Chi-square tests compared proportions and t-tests compared means.

Results: The study population included 263 S3, 71 S4, and 317 MET patients. Average age at index date was 51.9 years for S3, 54.4 years for SIV, and 52.8 years for MET patients (P = 0.080). Over the entire observable follow-up, 3.4% of S3 (17 per 1000 patient-years), 22.5% of S4 (119 per 1000 patient years), and 10.7% of MET patients (22 per 1000 patient years) died (P≤0.010 for comparisons). Mortality over the 1-year after index date was 1.1%, 12.7%, and 5.1% in the S3, S4, and MET groups respectively (P&lt;0.001). Patients who died in the first year after index date survived on average until 5.8 months (S3), 4.5 months (S4), and 7.3 months (MET) following the metastatic index date. Among MET patients, mean time to death from initial breast cancer diagnosis was 35.7 months for MET patients without endocrine treatment prior to chemotherapy (n = 157), and 76.1 months for other MET patients (n = 160) (P = 0.002). For S4 patients without endocrine treatment prior to chemotherapy (n = 34), patients survived an average of 10.0 months from initial advanced breast cancer diagnosis while the remaining S4 patients (n = 37) survived an average of 14.8 months.

Conclusions: Among patients with HR+/HER2- advanced breast cancer, mortality rates varied by stage of disease, and length of survival varied across patients pre-treated with endocrine therapy prior to chemotherapy compared with other patients. Further investigation of drivers behind differences in mortality may reveal the extent to which initial disease severity and sequencing of chemotherapy and endocrine therapy drive these variations.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-06-09.