Oncotype DX for Breast Cancer: Usage Consistent With Guidelines

Veronica Hackethal, MD

March 16, 2015

The 21-gene recurrence score (RS) assay Oncotype Dx (Genentech, Inc), which predicts the risk for metastasis in patients with early breast cancer and is used to aid treatment decisions, has been quickly adopted in clinical practice, according to a study published online March 5 in JAMA Oncology.

The study also found that use of the test seems to be consistent with clinical guidelines and is distributed equally across racial groups and geographic regions.

"To our knowledge, our study is the first nationally representative analysis of the adoption of the 21-gene RS assay in a community setting within the Medicare breast cancer population. We found that use of the assay was largely restricted to the populations for which it was initially approved in 2005, namely, women with ER-positive, LN-negative, stage I or II breast cancer, for which the test is most informative regarding the potential benefit of adjuvant chemotherapy," say the authors, led by Lesley Curtis, PhD, of Duke University School of Medicine, in Durham, North Carolina.

The 21-gene RS assay helps guide treatment decisions by predicting risk for metastasis and by identifying patients at high risk who could benefit from chemotherapy.

The Centers for Medicare and Medicaid Services approved coverage of the assay in 2006. The National Comprehensive Cancer Network (NCCN) and the American Society of Clinical Oncology guidelines also recommend the RS assay.

Dr Dinan and colleagues used the Surveillance, Epidemiology, and End Results (SEER) database linked to Medicare claims to identify Medicare beneficiaries diagnosed with breast cancer between 2005 and 2009. The SEER database represents about 25% of the US population with cancer. The analysis included patients aged 66 years or older at diagnosis (n = 70,802).

Results suggested that use of the RS assay increased from 1.1% in 2005 to 10.1% in 2009 (P < .001). The majority of tests (60.9%) were performed in patients with NCCN-defined intermediate-risk disease (estrogen-receptor positive, node-negative tumors > 1 cm).

Among those younger than 70 years with intermediate-risk disease, testing increased from 7.7% in 2005 to 38.8% in 2009 (P < .001). Testing remained uncommon in those older than 80 years (4.0% in 2009).

Among those with intermediate-risk disease (n = 18,128), testing was associated with younger age (49.8% vs 20.9% in those aged 66-70 years; P < .001), fewer comorbidities (9.6% vs 16.3% with multiple comorbidities), lower poverty (20.4% vs 23.7%; highest quartile for poverty, P < .001), being married (55.7% vs 40.9%; P < .001), living in the Northeast (24.0% vs 20.5%; P < .001), and having higher-grade disease (P < .001).

Multivariable analyses showed modestly higher testing in the Northeast compared with the West (odds ratio, 1.83; 95% confidence interval, 1.49 - 2.26). Otherwise, testing was not linked to region. About equal proportions of black patients received the test as did not (5.7% vs 5.9%, respectively; P = .69).

Overall, rates of chemotherapy use remained about the same between 2005 (16.2%) and 2009 (15.9%). Chemotherapy increased among those with intermediate disease, from 8.2% in 2005 to 10.0% in 2009, though the difference remained nonsignificant.

In a linked editorial, William Gradishar, MD, and Lisa Flaum, MD, both of Northwestern University Feinberg School of Medicine, in Chicago, Illinois, point out the need for better prognostic tools for breast cancer. This need is especially relevant, they write, for optimizing treatment and avoiding overtreatment among older patients. In particular, they emphasize the results showing lack of change in chemotherapy use among older patients.

"The data indicate that recurrence score results did not alter physicians' recommendation regarding adjuvant chemotherapy, which may reflect a pretest bias about using chemotherapy in this older patient population," commented Dr Gradishar.

Patient biases and preferences may play a "significant role" in patient acceptance of chemotherapy but could not be evaluated in this study, Dr Gradishar added. Physicians may also worry about whether older patients can tolerate the side effects of chemotherapy and its effects on quality of life.

"The physician and patient must have an accurate sense of what the risk of recurrence is, the likely life expectancy of a patient with or without [chemotherapy], other comorbidities, the expected side effects of therapy, and a realistic understanding of potential benefit from adjuvant chemotherapy," Dr Gradishar emphasized. "The 'right' decision is always personal and cannot be generalized for all patients."

The authors, Dr Flaum, and Dr Gradishar report no relevant financial relationships.

JAMA Oncol. Published online March 5, 2015. Abstract, Editorial

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