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Survival Results From PlanB Oncotype DX Study Hold Up in New Five-Year Outcome Analysis

NEW YORK (GenomeWeb) – Researchers from the West German Study Group shared updated five-year outcomes data from the PlanB study today at the 10th European Breast Cancer Conference in Amsterdam.

PlanB was initiated in 2009 as a trial comparing anthracycline-containing chemotherapy to anthracycline-free regimens in women with HER2-negative breast cancer.

Soon after its initiation, the trial was amended to recommend the use of Genomic Health's Oncotype DX breast cancer test to guide treatment. Patients with an Oncotype DX recurrence score (RS) under 12 were recommended to receive hormonal therapy alone, while participants with intermediate and high scores — RS of 12 or higher — were randomized as planned to different chemotherapy regimens.

Researchers from the trial published a report earlier this month in the Journal of Clinical Oncology showing that women in PlanB with Oncotype DX recurrence scores of 11 or less had 98 percent disease-free survival rates after three years, even if traditional parameters would have defined them as high risk.

In the new data presented at EBCC-10, the study authors updated their analysis of the same cohort with a median of 55 months’ follow-up, finding that 94 percent of early-stage breast cancer patients with an RS of 11 or less, who were treated with hormonal therapy alone, were disease-free about five years after their diagnoses.

Meanwhile, patients with an intermediate score — an RS of 12 to 25 — saw the same disease-free survival rates of 94 percent when treated with chemotherapy, while patients with an RS above 25 had a lower survival rate of 84 percent, despite receiving the same chemotherapy regimens.

Genomic Health said in a statement that the new five-year outcomes data, like the published three-year data, are consistent with conclusions of another large prospective trial — the Trial Assigning IndividuaLized Options for Treatment (Rx), or TAILORx, published in The New England Journal of Medicine last year — which focused only on node-negative subjects.

Meanwhile, the PlanB researchers will be extending their follow-up of the patients in the trial up to ten years. In addition, a follow-up trial called WSG-ADAPT has already enrolled more than 4,000 patients to look at combining the Oncotype DX RS with the assessment of early response to short-term preoperative anti-hormonal therapy as indicated by a decrease in the biomarker Ki67.

"The combination of both tools may help to omit adjuvant chemotherapy in about 50 percent to 60 percent of early breast cancer patients," Oleg Gluz, one of two scientific coordinators of the West German Study Group, said in a statement.