By Lori Solomon, Editor, Diagnostic Testing & Emerging Technologies
Oncotype DX assay (Genomic Health; Redwood City, Calif.), to assess a patient’s risk of recurrence, was adopted quickly in clinical practice after Medicare’s positive coverage decision, according to a study published online March 5 in JAMA Oncology. The authors further found that adoption appears to be consistent with clinical guidelines and equitable across geographic and racial groups. However, despite the assay’s goal to identify patients most likely to benefit from adjuvant chemotherapy, chemotherapy rates did not change as assay use increased, a finding the authors say warrants further investigation.
While the 21-gene recurrence predicting assay has been commercially available since 2004, the Centers for Medicare & Medicaid Services approved coverage for the use of the assay in 2006 for women with early-stage, estrogen receptor–positive, node-negative breast cancers to help guide treatment decisions regarding the need for adjuvant chemotherapy. Multi-gene assays, such as this one, have been developed to improve risk stratification in a way that standard clinicopathological factors cannot. Current guidelines recommend use of the assay to identify patients at low risk of developing metastatic disease who may safely forgo chemotherapy, as well as patients at high risk who stand to benefit the most from adjuvant chemotherapy.
The researchers utilized a data set that linked a Surveillance, Epidemiology, and End Results data with Medicare claims through 2010 to identify 70,802 Medicare beneficiaries diagnosed with incident breast cancer from 2005 to 2009.
The researchers found that the recurrence score (RS) assay was used for 3,684 patients (5.2 percent) overall, but use significantly increased from 1.1 percent in 2005 to 10.1 percent in 2009. The majority of tests (60.9 percent) occurred in patients with National Comprehensive Cancer Network–defined intermediate-risk disease. Testing was more likely in patients of younger age, were married, with fewer comorbid conditions, and had higher-grade disease. From 2005 to 2009 testing rates among patients younger than 70 years with intermediate-risk disease increased significantly from 7.7 percent to 38.8 percent in 2009. The authors characterized adoption as “relatively homogeneous” with regard to patient demographic and clinical characteristics. Only modest regional variation was seen and there was no significant racial variation in testing.
“Both in the overall study population and in patients with intermediate risk, we did not observe changes in rates of chemotherapy use over the study period,” note the authors led by Michaela A. Dinan, Ph.D., from Duke University in Durham, N.C. “However, further investigation is warranted to examine the association between use of the RS assay and chemotherapy in more detail.”