Abstract P2-08-13: Genetic testing for breast cancer and associated downstream utilization and costs
Authors: Kent Shia T , Chen Xiaoxue , Debono David , Lewis Karen , Agiro Abiy 
Published: March 2020

Abstract
Background: Given the clinical utility for diagnosis and treatment of hereditary breast cancer, the use of genetic testing is growing. However, few data exist on the association between genetic testing and subsequent clinical outcomes, healthcare utilization, and cost.
Objective: To examine medical utilization, cost, and survival in individuals with breast cancer who were tested for genes with high evidence for predicting breast cancer risk, as compared to those who were untested.
Methods: A retrospective observational study was conducted in commercial claims. Adult women with non-metastatic breast cancer during 2013-2017 were identified and divided into two groups: (1) a genetic testing group (GTG) that was tested during January 2014-June 2017 for high risk genes for hereditary breast cancer (BRCA, PTEN) and (2) a no genetic testing group (NGTG) that did not test for any genes or gene expression for hereditary breast cancer. Members in the NGTG were matched 1:1 to the GTG by propensity scores using age, region, baseline clinical variables (other cancer types, breast imaging, breast biopsy, Deyo-Charlson Comorbidity Index), and baseline all-cause and cancer-related costs. Utilization and cost outcomes were assessed during 1 year post-genetic testing. We also estimated survival and all-cause healthcare costs during full follow-up, in the main sample and in a “3-year” sample of women who took their first genetic test at least 3 years prior to study end. Variables remained unbalanced after matching were adjusted in regression modeling.
Results: The study identified 12,236 patients in the GTG and 53,125 patients in the NGTG. All patient covariates, except baseline cancer-related costs, were balanced after 1:1 propensity score matching (n=10,887 matched patients in each group). In the GTG and NGTG, 18% and 1%, respectively, had follow-up genetic testing (p&lt;.001). The GTG, compared to the matched NGTG, was more likely to have breast imaging (adjusted odds ratio [aOR] 1.43; 95% confidence interval [CI] 1.35-1.51), breast biopsy (aOR 2.24; 95% CI 2.02-2.49), breast surgery (aOR 2.76; 95% CI 2.62-2.91), and other cancer treatments during 1 year of follow-up (Table; all p&lt;0.001, except mammogram p-value=0.002). All-cause healthcare cost was $27,131 higher among GTG compared to NGTG during 1 year of follow-up ($78,733 versus $51,602; p&lt;0.001) and remained high at 3 years ($55,479 versus $38,037 per-member-per-year; p&lt; 0.001). Genetic testing for breast cancer was not associated with difference in survival (overall adjusted hazard ratio [aHR] 1.17, 95% CI 0.82-1.67; 3-year aHR 0.77, 95% CI 0.23-2.63).
Conclusions: Increased treatment and healthcare costs are likely to follow genetic testing and should be discussed in the shared decision-making process. Survival analyses were inconclusive due to low rate of mortality.
Citation Format: Shia T Kent, Xiaoxue Chen, David Debono, Karen Lewis, Abiy Agiro. Genetic testing for breast cancer and associated downstream utilization and costs [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P2-08-13.