The influence of 21-gene recurrence score assay on chemotherapy use in a population-based sample of breast cancer patients

• Type of Material: Article
• Authors: Yun Li, University of Michigan; Allison W. Kurian, Stanford University; Irina Bondarenko, University of Michigan; Jeremy M.G. Taylor, University of Michigan; Reshma Jagsi, University of Michigan; Kevin C. Ward, Emory University; Ann S. Hamilton, University of Southern California; Steven J. Katz, University of Michigan; Timothy P. Hofer, University of Michigan
• Language: English
• Date: 2017-02-01
• Publisher: Springer Verlag
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2016, Springer Science+Business Media New York.
• Final Published Version (URL): http://dx.doi.org/10.1007/s10549-016-4086-3
• Title of Journal or Parent Work: Breast Cancer Research and Treatment
• ISSN: 0167-6806
• Volume: 161
• Issue: 3
• Start Page: 587
• End Page: 595
• Grant/Funding Information: The collection of cancer incidence data in Georgia was supported by contract HHSN261201300015I, Task Order HHSN26100006 from the NCI and cooperative agreement 5NU58DP003875-04-00 from the CDC. The ideas and opinions expressed herein are those of the author(s) and endorsement by the State of California, Department of Public Health, the NCI, and the CDC or their Contractors and Subcontractors is not intended nor should be inferred.; The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript.; This work was supported by the National Cancer Institute (P01CA163233 to the University of Michigan). The collection of cancer incidence data used in this study was supported by the California Department of Public Health pursuant to California Health and Safety Code Section 103885; Centers for Disease Control and Prevention’s (CDC) National Program of Cancer Registries, under cooperative agreement 5NU58DP003862-04/DP003862; the NCI’s Surveillance, Epidemiology and End Results Program under contract HHSN261201000140C awarded to the Cancer Prevention Institute of California, contract HHSN261201000035C awarded to the University of Southern California (USC), and contract HHSN261201000034C awarded to the Public Health Institute.
• Keywords: Chemotherapy; Oncology; 21-gene recurrence score assay; Life Sciences & Biomedicine; Breast cancer; Population studies; Science & Technology
• Research Categories: Health Sciences, Radiology; Health Sciences, Oncology

Abstract

Purpose: To quantify the influence of RS assay on changing chemotherapy plans in a general practice setting using causal inference methods. Methods: We surveyed 3880 newly diagnosed breast cancer patients in Los Angeles and Georgia in 2013–14. We used inverse propensity weighting and multiple imputations to derive complete information for each patient about treatment status with and without testing. Results: A half of the 1545 women eligible for testing (ER+ or PR+, HER2−, and stage I–II) received RS. We estimate that 30% (95% confidence interval (CI) 10–49%) of patients would have changed their treatment selections after RS assay, with 10% (CI 0–20%) being encouraged to undergo chemotherapy and 20% (CI 10–30%) being discouraged from chemotherapy. The subgroups whose treatment selections would be changed the most by RS were patients with positive nodes (44%; CI 24–64%), larger tumor (43% for tumor size > 2 cm; CI 23–62%), or younger age (41% for < 50 years, CI 23–58%). The assay was associated with a net reduction in chemotherapy use by 10% (CI 4–16%). The reduction was much greater for women with positive nodes (31%; CI 21–41%), larger tumor (30% for tumor size > 2 cm; CI 22–38%), or younger age (22% for < 50 years; CI 9–35%). Conclusion: RS substantially changed chemotherapy treatment selections with the largest influence among patients with less favorable pre-test prognosis. Whether this is optimal awaits the results of clinical trials addressing the utility of RS testing in selected subgroups.