Breast Cancer Research and Treatment

, Volume 161, Issue 3, pp 587–595

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

  • Yun Li
  • Allison W. Kurian
  • Irina Bondarenko
  • Jeremy M. G. Taylor
  • Reshma Jagsi
  • Kevin C. Ward
  • Ann S. Hamilton
  • Steven J. Katz
  • Timothy P. Hofer
Epidemiology

DOI: 10.1007/s10549-016-4086-3

Cite this article as:
Li, Y., Kurian, A.W., Bondarenko, I. et al. Breast Cancer Res Treat (2017) 161: 587. doi:10.1007/s10549-016-4086-3

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.

Keywords

Breast cancer 21-gene recurrence score assay Chemotherapy Population studies 

Supplementary material

10549_2016_4086_MOESM1_ESM.docx (20 kb)
Online Appendix (DOCX 19 kb)

Copyright information

© Springer Science+Business Media New York 2016

Authors and Affiliations

  • Yun Li
    • 1
  • Allison W. Kurian
    • 2
  • Irina Bondarenko
    • 1
  • Jeremy M. G. Taylor
    • 1
  • Reshma Jagsi
    • 3
  • Kevin C. Ward
    • 4
  • Ann S. Hamilton
    • 5
  • Steven J. Katz
    • 6
    • 7
  • Timothy P. Hofer
    • 6
    • 8
  1. 1.Department of BiostatisticsUniversity of MichiganAnn ArborUSA
  2. 2.Departments of Medicine and Health Research and PolicyStanford UniversityStanfordUSA
  3. 3.Department of Radiation OncologyUniversity of MichiganAnn ArborUSA
  4. 4.Department of EpidemiologyEmory UniversityAtlantaUSA
  5. 5.Keck School of MedicineUniversity of Southern CaliforniaAnn ArborUSA
  6. 6.Department of Internal MedicineUniversity of MichiganAnn ArborUSA
  7. 7.Department of Health Management and PolicyUniversity of MichiganAnn ArborUSA
  8. 8.Ann Arbor Veterans Affairs Medical CenterAnn ArborUSA