Initial Trends in the Use of the 21-Gene Recurrence Score Assay for Patients With Breast Cancer in theMedicare Population, 2005-2009.

Dinan MA1, Mi X2, Reed SD1, Hirsch BR1, Lyman GH3, Curtis LH4.

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Abstract

IMPORTANCE:

In 2006, the Centers for Medicare & Medicaid Services approved coverage for the use of the 21-gene recurrence score (RS)assay in women with early-stage, estrogen receptor-positive, node-negative breast cancers to help guide recommendations for adjuvant chemotherapy. Use of the assay in community settings has not been previously examined in a nationally representative sample of patients.

OBJECTIVE:

To examine trends in the use of the RS assay in routine clinical practice in a nationally representative sample of women with breastcancer.

DESIGN, SETTING, AND PARTICIPANTS:

Retrospective observational study of Medicare beneficiaries diagnosed with incident breast cancerbetween 2005 and 2009, as recorded in a Surveillance, Epidemiology, and End Results data set with linked Medicare claims through 2010.

MAIN OUTCOMES AND MEASURES:

Demographic and clinical variables associated with the use of the assay.

RESULTS:

A total of 70,802 patients met the study criteria. Use of the RS assay increased from 1.1% in 2005 to 10.1% in 2009 (P < .001). The majority of tests (60.9%) occurred in patients with National Comprehensive Cancer Network-defined intermediate-risk disease (ie, estrogen receptor-positive, node-negative tumors >1 cm). Most patients with other than intermediate-risk disease had borderline indications for testing, including T1b (47.5%) or N1 (26.8%) disease. Testing was associated with younger age, fewer comorbid conditions, higher-grade disease, and being married. Among patients younger than 70 years with intermediate-risk disease, testing rates increased from 7.7% in 2005 to 38.8% in 2009 (P < .001). In multivariable analysis, testing was modestly higher in Northeast than in Western registries (odds ratio, 1.83; 95% CI, 1.49-2.26) but was otherwise not associated with region, local census tract demographic characteristics, black race, location in an urban area, or tumor histologic characteristics.

CONCLUSIONS AND RELEVANCE:

The RS assay was adopted quickly in clinical practice after the Medicare coverage decision in 2006, and use appears to be consistent with guidelines and equitable across geographic and racial groups. Factors influencing adoption of the assay and its impact on adjuvant chemotherapy use in clinical practice remain important areas of study.