Abstract
e11094 Background: The MammaPrint 70-gene expression profile (MP) is a powerful predictor of disease outcome in early stage breast cancer. In addition, TargetPrint (TP), a microarray-based test that measures the mRNA expression level of ER, PR and HER2 was developed. In the present study, MP was measured in a prospective U.S. breast cancer patient cohort to determine how MP compares to treatment advice according to NCCN consensus guidelines and how TargetPrint results compare to IHC/FISH. Methods: MP results were evaluated in fresh tumor samples from 111 breast cancer patients (T1-4N0-2; median age 62 [39 -97 yr]) collected by core needle biopsy or from a surgical specimen between July 2008 and November 2010. We compared treatment advice as recommended by NCCN guidelines and classification according to MP. A direct comparison was also made between MP and the Oncotype DX (ODX) assay in a small subset of patients. In addition, we compared IHC/FISH ER, PR and HER2 assessments with TP. Results: According to NCCN treatment recommendations, 6 patients should receive adjuvant endocrine therapy: 5 of these patients were classified as High Risk and 1 as Low Risk by MP. For another 5 patients, NCCN recommendations could not be determined due to a missing clinical parameter (all high risk by MP). For the remaining 100 patients, NCCN guidelines recommends (n=46) or suggests to consider (n=54) adjuvant chemotherapy (CT): 24 of these patients were classified as MP Low Risk and the remaining as MP High Risk. Comparison of TP with IHC/FISH indicated a concordance of 98% for ER, 90% for PR, and 93% for HER2. For 19 patients the ODX assay was also performed, resulting in 4 patients classified as low risk ODX: 3 are MP High Risk and 1 is MP Low Risk. Fifteen patients classified as intermediate risk ODX; 14 were High Risk MP and 1 was Low Risk MP. Conclusions: For the 100 (94%) out of 111 patients from 7 US hospitals, NCCN guidelines either recommended or suggested considering adjuvant CT. In contrast, MP indicated a Low Risk of recurrence in 24 of these cases. Integration of MP into clinical risk assessment could improve the management of early-stage breast cancer and avoid unnecessary CT for Low Risk patients.
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