NEW YORK (GenomeWeb) – In JAMA Oncology, researchers from Duke University and elsewhere looked at the uptake and use of Genomic Health's Oncotype DX breast cancer recurrence assay in Medicare beneficiaries in the years following its coverage approval.
The assay is based on the expression of 21 recurrence-related genes, authors of the analysis explained. It's designed to predict the risk of metastasis in women with estrogen receptor-positive breast cancer that has not spread to the lymph node. That, in turn, may help gauge the potential benefits of post-surgical chemotherapy in patients with ER-positive, lymph node-negative tumors.
The 21-gene recurrence score assay was approved for Medicare coverage in 2006. To get a sense of how it's been applied since then, the team considered data for 70,802 Medicare recipients diagnosed with breast cancer between 2005 and 2009, using information from Medicare and the Surveillance, Epidemiology, and End Results (SEER) program.
Not surprisingly, the analysis points to a jump in the use of Oncotype DX in the years after coverage: in 2005 the assay was used for just 1.1 percent of women compared to 10.1 percent in 2009.
The study's authors pointed out that its use "was largely restricted to the populations for which it was initially approved in 2005, namely women with ER-positive, [lymph node]-negative, stage I or II breast cancer for which the test is most informative regarding the potential benefits of adjuvant chemotherapy."
Nevertheless, they noted that chemotherapy rates held steady at around 16 percent overall in both 2005 and 2009. Around 10 percent of patients with intermediate-risk breast cancer received chemotherapy in 2009 compared with 8.2 percent in 2005 — an increase that did not reach statistical significance.
Women from urban and rural sites appeared to have equitable access to the test, as did patients with different racial backgrounds, the researchers reported. Testing with Oncotype DX was slightly more common in the Northeast and amongst women under 70 years old who had higher grade disease and/or fewer co-morbidities.
In Southern parts of the country, the test was used somewhat more often for non-intermediate-risk patients who didn't clearly fit current testing guidelines for the Oncotype DX recurrence score assay.
Those involved in the analysis noted that additional research is needed to verify such patterns, since the SEER registry has a high proportion of non-Caucasian individuals from urban and/or resource-limited areas.
Further research is also needed to assess the relative benefits of chemotherapy in patients with high-, low-, or intermediate-recurrence scores, particularly given the relatively steady chemotherapy rates detected despite more widespread use of the assay.
In an accompanying commentary article in JAMA Oncology, Northwestern University physicians Lisa Flaum and William Gradishar, who were not involved in the analysis, discussed physicians' potential reticence to alter chemotherapy use based on recurrence test results, particularly when treating older patients.
"The lack of change in chemotherapy utilization suggests either that the physicians have a bias about treating older patients with chemotherapy that the test did not change regardless of results, or that the test results were concordant with their pretest bias," Flaum and Gradishar wrote.
"If the use of the [recurrence score] assay is not altering treatment recommendations in the older patient population, it would be interesting to document whether this is related to tumor characteristics, physician bias, or patient preference," they argued. "A prospective study of physician and patient decision-making in this patient age group would also be useful in answering some of these questions."