The influence of 21-gene recurrence score assay on chemotherapy use in a population-based sample of breast cancer patients
Published Date:Dec 23 2016
Source:Breast Cancer Res Treat. 161(3):587-595.
Pubmed Central ID:PMC5243200
HHSN261201000140C/CA/NCI NIH HHS/United States
P01 CA163233/CA/NCI NIH HHS/United States
U58 DP003875/DP/NCCDPHP CDC HHS/United States
HHSN261201300015C/RC/CCR NIH HHS/United States
HHSN261201000035I/CA/NCI NIH HHS/United States
HHSN261201000034C/CA/NCI NIH HHS/United States
U58 DP003862/DP/NCCDPHP CDC HHS/United States
To quantify the influence of RS assay on changing chemotherapy plans in a general practice setting use using causal inference methods.
We surveyed 3,880 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.
Half of the 1,545 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%).
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.
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