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Data Supports Oncotype DX for Predicting Recurrence in Node-Positive Cancers, Guiding Radiation Therapy

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In support of expanded utility for its Oncotype DX test in guiding cancer therapy decision-making, Genomic Health announced new data this week demonstrating that the test can help predict patients' risk of loco-regional recurrence after receiving chemotherapy and hormonal therapy for node-positive, estrogen-receptor positive breast cancers.

In a poster presented at the Society of Surgical Oncology Annual Cancer Symposium this month, the company reported that an analysis of patients from the National Surgical Adjuvant Breast and Bowel Project B-28 trial suggests that the test can accurately stratify patients based on their risk of loco-regional recurrence. This information could help physicians make better decisions about whether and how to treat patients with additional radiotherapy, researchers from the study suggested.

Oncotype DX is used most readily in node-negative women. But the test has also been validated to gauge recurrence in women whose disease has spread to the lymph nodes and Genomic Health also offers a version of the test for establishing recurrence risk in ductal in situ carcinoma.

The new data, described in an abstract for the plenary sessions of the meeting, follows analysis of 1,065 patients from the larger NSABP trial, which looked at the effectiveness of paclitaxel and doxorubicin/cyclophosphamide-based adjuvant chemotherapy compared to doxorubicin/cyclophosphamide alone in patients with resected node-positive breast cancer.

In the study, researchers looked at 1,065 patients from the NSABP trial that had ER+ cancer and also had an Oncotype DX recurrence score calculation. Among this cohort, which was followed for 11 years, there were 80 loco-regional recurrences, the authors reported.

According to the study abstract, the 10-year cumulative incidence of loco-regional recurrence was 3.3 percent for patients with a low recurrence score result, 7.2 percent for those with an intermediate RS, and 12.3 percent for those with high recurrence scores.

The group reported that Oncotype RS was a "significant predictor of LRR in univariate analyses," and remained an independent predictor in multivariate regression analysis adjusting for treatment and type of surgery.

According to the authors, the findings "have clinical implications regarding selection of appropriate candidates for comprehensive [radiation therapy]." Patients at high risk for local or regional recurrence might consider undergoing post-mastectomy chest wall radiation therapy or node radiation therapy, for example.

In a statement, Steven Shak, Genomic Health's chief medical officer, said that based on the results, "we now have evidence suggesting the value of the Oncotype DX result in tailoring the intensity and extent of radiation in breast cancer patients with node-positive disease."

According to Shak's statement, Genomic Health plans to release data soon on ductal in situ carcinoma, another area where the company is hoping to drive adoption of Oncotype DX as a tool to gauge the need for radiation therapy based on recurrence score (PGx 2/13/2013).

The company has acknowledged previously that adoption of Oncotype DX for DCIS has been hindered by delays in publication of validation data showing the test can predict recurrence indicating the need for radiation therapy in addition to surgery (PGx 11/14/2012).

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