Abstract P2-08-13: Survival in women with de novo metastatic breast cancer: Comparison of real-world evidence from publicly-funded Canadian province and the United States by insurance status

Abstract

Background: Access to cancer screening, diagnosis and treatment in the United States (US) is affected by insurance status; whereas, access within a publicly-funded health care system is similar across the whole population. The aim of this study was to compare overall survival (OS) of de novo stage IV (metastatic) breast cancer (BC) pts in a Canadian province and in the US according to insurance status. Methods: All female pts 18-64 yrs of age diagnosed with de novo stage IV BC from Jan 1, 2010 through Dec 31, 2014 with available biomarker information were included. Pts diagnosed by death certificate or autopsy and pts ≥ 65 yrs were excluded due to unreliable insurance status classification in the US SEER database. The Alberta cohort (AB) was obtained from the Alberta Health Services CancerControl Breast Data Mart (BDM), a repository of information on all pts diagnosed with their first BC diagnosis from Jan 1, 2004 onwards in the province of Alberta, Canada. The U.S. cohort was obtained from the US Surveillance, Epidemiology, and End Results (SEER) program cancer database. A total of 9,604 pts from the SEER database and 294 pts from the BDM were analyzed. OS was evaluated over a 2 yr period and median and 2 yr OS were estimated. Unadjusted associations were compared using the log-rank test, and hazard ratios (HR) were estimated using the Cox proportional hazards model with US insured set as reference group. Results: Comparison of AB and US cohorts showed no differences based on age group (18-49 vs 50-64), yr of diagnosis or receipt of primary surgery. The AB cohort had a higher incidence of hormone receptor positive (HR+), similar frequency of HER2+, and a lower incidence of triple negative (TN) BC relative to the US cohort: HR+ 60.5% vs 56.4%; HER2+ 30.6% vs 28.8%; and TN 8.8% vs 14.8%, respectively [p=0.017]. The distribution of HR+, HER2+ and TN BC was consistent between the SEER insured, Medicaid and uninsured groups. AB cohort estimated 2 yr OS was 70.1%, similar to the insured group of 66.0% and significantly better than the Medicaid or uninsured pts [53.2% and 50.9%; p<0.0001]. Subgroup analysis based on biomarker status, surgery and age group showed similar results. Adjusting for these variables, AB OS remained similar to the insured group [HR=0.92 (0.74-1.15) p=0.474] with worse OS noted in the Medicaid and uninsured populations [HR=1.44 (1.32-1.56) and HR=1.53 (1.33-1.77) p<0.001, respectively]. HR+HER2+TNNo SurgerySurgery18-4950-64InsuredReference Group: HR=1.00AB0.92 (0.68-1.24) p=0.5841.15 (0.76-1.72) p=0.5090.84 (0.49-1.42) p=0.5070.91 (0.71-1.17) p=0.4660.71 (0.45-1.11) p=0.1330.84 (0.56-1.27) p=0.4080.87 (0.67-1.12) p=0.284Medicaid1.43 (1.27-1.61) p<0.0011.57 (1.32-1.87) p<0.0011.37 (1.18-1.60) p<0.0011.46 (1.33-1.59) p<0.0011.55 (1.33-1.81) p<0.0011.75 (1.52-2.00) p<0.0011.47 (1.34-1.61) p<0.001Uninsured1.76 (1.44-2.15) p<0.0011.64 (1.20-2.22) p<0.0011.56 (1.20-2.05) p=0.0011.56 (1.34-1.80) p<0.0011.59 (1.16-2.18) p=0.0041.76 (1.35-2.29) p<0.0011.67 (1.43-1.94) p<0.001 Conclusion: OS in women with de novo stage IV BC in AB was similar to US insured. AB and US insured experienced superior OS compared with US Medicaid and uninsured. Citation Format: Kornaga EN, Matutino AR, Pereira AA, Verma S, Lupichuk S. Survival in women with de novo metastatic breast cancer: Comparison of real-world evidence from publicly-funded Canadian province and the United States by insurance status [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P2-08-13.

First-Line Treatment with a Cyclin-Dependent Kinase 4/6 Inhibitor Plus an Aromatase Inhibitor for Metastatic Breast Cancer in Alberta

“…While median OS in our cohort has not yet been reached, OS at 3 years was 68%. This result is comparable to OS at 3 years for the palbociclib + letrozole cohort from the Flatiron database (72%) [ 20 ] and superior to a historical Alberta cohort of de novo HR-positive, HER2-negative MBC patients aged <65 years who were diagnosed 1 January 2010 through 31 December 2014 and would not have had access to a CDK4/6i in the first-line setting (56%) [ 27 ]. In terms of the pivotal RCTs of CDK4/6 inhibitors + AI, only Monaleesa-7 (all pre-menopausal patients with ovarian function suppression) reported OS, which was significantly better in the ribociclib arm (OS at 42 months, 70% vs. 46%; HR, 0.71, 95% CI, 0.54–0.95) [ 28 ].…”