Nick Mulcahy

March 12, 2015

HOLLYWOOD, Florida — The National Comprehensive Cancer Network (NCCN) only endorses one genomic test for use in patients with early-stage breast cancer, according to a presenter here at the NCCN 20th Annual Conference.

Oncotype DX, a 21-gene assay from Genomic Health, has won that honor, said presenter Amy Cyr, MD, from the Siteman Cancer Center at Washington University in St. Louis, Missouri.

The test serves two functions. In addition to providing a prognosis, the test has "some prediction capabilities in terms of therapy; it actually predicts a response to chemotherapy, compared with no chemotherapy," she explained.

In short, Oncotype DX is both prognostic and predictive.

The ability to predict response to treatment "is what, so far, makes this test stand out," she said.

The other molecular tests for breast cancer, including MammaPrint, Prosigna, EndoPredict, and Breast Cancer Index, have not yet shown evidence of both capabilities, she added.

Oncotype DX is only indicated for use in women with hormone-receptor-positive disease (that is also HER2-negative, as well as being pT1, PT2, or pT3 and pN0 or pN1).

There has been a growing market for the test, Dr Cyr suggested, because it is indicated for use in early-stage disease, which is being diagnosed in "more and more women" as a result of mammography screening.

Molecular profiling tests are "one of the most exciting things" going on in medical oncology, Dr Cyr said, and more data are forthcoming on the various tests for breast cancer.

"The Oncotype DX test is somewhere between helpful and extremely helpful," said Michael Stone, MD, a medical oncologist at the Greeley Medical Clinic, which is part of the University of Colorado Health System.

The test predicts the risk for recurrence, either local or metastatic, said Dr Stone, who attended the presentation.

Patients appreciate the test. "Most of my patients are pretty happy that there is a chance they won't need chemotherapy," he told Medscape Medical News.

Chemotherapy is not recommended for patients with a low recurrence score but is recommended for those with a high recurrence score. An intermediate recurrence score, however, is a grey area, Dr Stone explained.

He said he bases his decision on whether to recommend chemotherapy on his patients' age and health status, mainly. He generally recommends chemotherapy to the younger and healthier postmenopausal women with an intermediate recurrence score.

Dr Cyr agrees that it's "hard to know" where women with intermediate scores fall.

Moving forward, Dr Stone said he believes that the MammaPrint test will be more widely used in the United States.

MammaPrint was limited to use in fresh tissue, but now can be used to analyze fixed tissue as well, he reported. This flexibility removes the issue of timing, which was a limitation of the test.

However, MammaPrint is currently only a prognostic test, Dr Cyr pointed out.

She noted that although Oncotype DX is limited to use in node-negative patients, it appears to have utility in node-positive patients.

She cited the TransATAC (Anastrozole, Tamoxifen, Alone or in Combination) study of postmenopausal women with breast cancer who were treated with either anastrozole or tamoxifen (J Clin Oncol. 2010;28:1829-1834). Their tumor tissue was analyzed with Oncotype DX and recurrence was tabulated in node-negative and node-positive patients.

"The recurrence score was predictive of long-term outcomes" in both sets of patients, said Dr Cyr. Notably, it was comparably predictive in node-positive patients with three or fewer nodes and in those with four or more nodes.

Dr Cyr and Dr Stone have disclosed no relevant financial relationships.

National Comprehensive Cancer Network (NCCN) 20th Annual Conference. Presented March 12, 2015.

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