Assessing Barriers to Genetic and Tumor Genome Sequence Testing in Patients with Metastatic Stage IV Breast Cancer at an Academic and Public Hospital in Georgia Restricted; Files Only

Abstract

Genetic testing and tumor genome sequencing are essential in the management of metastatic stage IV breast cancer, enabling identification of actionable mutations that guide targeted therapy and improve outcomes. Despite guideline recommendations, uptake remains suboptimal, particularly in underserved populations. This study evaluated rates of germline genetic testing and tumor genome sequencing and identified factors associated with their use among patients treated at an academic center (Emory Winship Cancer Institute) and a safety-net hospital (Grady Memorial Hospital) in Georgia. We conducted a retrospective chart review of patients diagnosed with stage IV breast cancer from 2015 to 2020 who met eligibility criteria for genetic and/or tumor sequencing. Data collected included demographics, tumor characteristics, provider factors, and insurance status. Descriptive analyses and multivariable logistic regression were performed. Among 253 eligible patients (182 Emory, 71 Grady), genetic testing rates were low (41.8% vs 46.5%), as were tumor sequencing rates (51.5% vs 40.7%). Reasons for non-receipt were often undocumented. Among those tested, 32.4% had positive genetic results, including 16% with pathogenic mutations, most commonly BRCA1/2. Tumor sequencing identified actionable mutations in 55.7% of patients, frequently ESR1 and PIK3CA, with over half resulting in management changes. Government insurance was associated with significantly lower odds of both tests. Tumor subtype influenced testing patterns, with higher genetic testing in triple-negative disease and lower sequencing in HER2-positive disease. Race, institution, and provider factors were not independently associated after adjustment. In conclusion, utilization of genetic testing and tumor genome sequencing in stage IV breast cancer remains suboptimal. Insurance status and tumor biology significantly influence testing, underscoring the need for system-level interventions to improve equitable access to precision oncology.

Table of Contents

Distribution Agreement .......................................................................................................................... i

Approval Page .......................................................................................................................................... ii

Abstract .................................................................................................................................................... iii

Cover Page ……………………………………………………………………………………iv

Background...........................................................................................................................1

  Genetic Testing .........................................................................................................................................2

  Tumor Genome Sequence Testing ........................................................................................................6

   Purpose of the Study ............................................................................................................................ 10

Methods ...................................................................................................................................................11

  Study Design .......................................................................................................................................... 11

  Statistical Analysis ................................................................................................................................. 14

Results .....................................................................................................................................................15

Discussion ................................................................................................................................................ 23

Conclusion and Future Directions ..................................................................................................... 26

References ................................................................................................................................................27

About this Master's Thesis

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School	Laney Graduate School
Department	Clinical Research
Degree	M.S.
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Epidemiology Health Sciences, Oncology
Keyword	genomic testing tumor genome sequence testing health disparities breast cancer genetic testing
Committee Chair / Thesis Advisor	Kempker, Jordan, Emory University Manatunga, Amtia , Emory University
Committee Members	Gillespie, Theresa, Emory University Kalinsky, Kevin, Emory University

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