Oncotype DX Test for Breast Cancer Finds Clinical Acceptance, but Disparity Exists

The 21-gene Recurrence Score assay, also known as the Oncotype DX Breast Cancer Assay, has been developed to predict disease recurrence and response to chemotherapy in estrogen receptor—positive, lymph node–negative early stage breast cancer (EBC). A retrospective research study has identified disparity in the use of this test, primarily driven by race, insurance status, and the type of facility where treatment was administered.

Researchers at the University of Colorado Cancer Center analyzed 143,032 records of patients diagnosed with EBC between 2004 and 2012, included in the National Cancer Data Base. “We meant this study as a kind of state of the union for the use of this test. What we found were some pretty stark disparities along socioeconomic and racial lines,” said Jagar Jasem, MD, MPH, investigator at the CU Cancer Center and the study’s lead author, in a statement.

According to the company website, this assay predicts chemotherapy benefit and the likelihood of distant breast cancer recurrence in those who have been diagnosed with an invasive form of the disease. It can also predict the risk of local recurrence in those who have the more common non-invasive form of breast cancer, ductal carcinoma in-situ or DCIS. A glimpse into the molecular make-up of the patients tumor, using this 21-gene assay, has changed treatment decisions, according to Genomic Health, the test developer—a low Recurrence Score resulted in 33% of a study population to switch from hormonal therapy plus chemotherapy to hormonal therapy alone. This test can therefore protect those with low grade disease from the unnecessary adverse effects of chemotherapy, but can also ensure more aggressive treatment for those who really need it.

In the present study, the authors found that the assay was ordered in 54% of the study population, and the assay presented a very strong association with the recommendation for chemotherapy. Further, test use was strongly associated with younger age, white race, academic centers, private insurance, and pT2/pN0(i+) grade 2 to 3 disease. African American patients (adjusted odds ratio [AOR], 1.31; 95% CI, 1.20 to 1.43) and those treated at community facilities (AOR, 1.49; 95% CI, 1.35 to 1.63) were more likely to be treated outside of the National Comprehensive Cancer Network guidelines, the authors write. Further, younger African American patients were more likely to receive chemotherapy (AOR, 1.33; 95% CI, 1.16 to 1.54) despite a low Recurrence Score.

This shows that younger African American patients were in fact over-treated, and the African American patients overall were under-tested. “We show that doctors are absolutely using this test to decide who gets chemotherapy along with their treatment. In fact, of all the variables we explored, this test was most strongly associated with the chance that a patient goes on to receive chemotherapy. But what we show is that the treatment of minority and low socioeconomic patients is more likely to be disconnected from these test results,” according to Jasem.

Reference

Jasem J, Amini A, Rabinovitch R, et al. 21-gene Recurrence Score assay as a predictor of adjuvant chemotherapy administration for early-stage breast cancer: an analysis of use, therapeutic implications, and disparity profile [published online March 21, 2016]. J Clin Oncol. pii: JCO650887.