This article is more than 5 years old. Information may no longer be current.
Impact of recurrence score assay on chemotherapy receipt varies based on breast cancer risk
The use of a 21-gene recurrence score assay appeared associated with greater use of chemotherapy in patients with low-risk breast cancer and a reduced use of chemotherapy in high-risk patients, according to results of a retrospective cohort study of Medicare beneficiaries.
The 21-gene recurrence score assay (Oncotype DX), or RS assay, uses an algorithm based on gene expression to predict the probability of recurrence of hormone-receptive breast cancer and to estimate the benefit of adjuvant chemotherapy. Guidelines recommend physicians consider the use of chemotherapy for patients with early-stage, ER-positive invasive breast cancer, and the 21-gene RS assay may prove cost-effective by prompting more appropriate chemotherapy usage in this population.
Michaela A. Dinan, PhD, assistant professor of medicine at Duke University, and colleagues used the SEER database linked with Medicare claims to identify a broadly representative view of RS assay use and its association with chemotherapy receipt for patients diagnosed with ER-positive breast cancer between 2005 and 2009, the time immediately following the 2004 introduction of the RS assay by Paik and colleagues (N Engl J Med. 2004;351:2817-2826).
The analysis included data from 44,044 patients aged at least 65 years who had low-risk (24%), intermediate-risk (51.3%) or high-risk, lymph-node positive (24.6%) disease.
The primary outcome of the study was the receipt of chemotherapy within 1 year of diagnosis.
Researchers observed no overall association between receipt of the 21-gene RS assay and chemotherapy usage (OR = 1.03; 99% CI, 0.88-1.19).
However results of a multivariate analyses showed that compared with no receipt of the RS assay, its use appeared associated with lower chemotherapy use in high-risk patients (OR = 0.36; 99% CI, 0.26-0.5) and greater chemotherapy use in low-risk patients (OR = 3.71; 99% CI, 2.3-5.98; P = .006).
Results of a subgroup analysis of patients aged 70 or younger demonstrated comparable outcomes with the exception of a shift toward reduced chemotherapy use in 2008 (OR = 0.9; 99% CI, 0.77-1.05) and 2009 (OR = 0.81; 99% CI, 0.66-0.99; P = .007).
Unadjusted analyses showed overall chemotherapy usage decreased over time for high-risk patients aged 70 years or younger who received the RS assay.
Hospital referral region-level analysis did not demonstrate a significant association between regional adoption of the RS assay and changes in chemotherapy use in the overall population as well as those aged younger than 70 years.
“Contrary to our hypothesis, we did not observe a change in chemotherapy use in the overall study population after the adoption of the RS assay between 2005 and 2009 or a general association between receipt of chemotherapy and use of the assay in multivariable analyses or [hospital referral region]-level analyses,” Dinan and colleagues wrote. “[However] our data suggest that use of the RS assay may have decreased chemotherapy use in general practice among younger patients with high-risk disease in whom receipt of chemotherapy would have otherwise been likely but that it was associated with greater chemotherapy in use in patients with low-risk disease. The impact of the RS assay on chemotherapy use is likely population dependent and is influenced by the population’s pretest likelihood of undergoing chemotherapy.”
Allison W. Kurian
Questions remain regarding why physicians choose to order an RS assay, if physicians follow the recommendations of the RS assay results, and what role patients play in the decision to order an RS assay and undergo chemotherapy, Allison W. Kurian, MD, MSc, assistant professor of medicine (oncology) and health policy and research at Stanford University Medical Center and Christopher R. Friese, PhD, RN, AOCN, FAAN, assistant professor in the department of systems, population and leadership at University of Michigan School of Nursing, wrote in an invited commentary.
“Ultimately, we cannot assess the effects of RS assay use on breast cancer treatment without a deeper understanding of patients’ and physicians’ perspectives,” Kurian and Friese wrote. “As tumor and germline assays expand from 21 genes to the whole genome, there is growing need for a framework to evaluate the contribution of precision medicine to cancer treatment quality.” – by Anthony SanFilippo
Disclosure: The researchers, Kurian and Friese all report no relevant financial disclosures.