MammaPrint Predicts Survival in Small Breast Cancer Tumors
GA Seitz, AM Glas, P Roepmann, F de Snoo, L van't Veer. Klinikum Bamberg, Bamberg, Germany; Agendia PV, Amsterdam, Netherlands; Netherlands Cancer Institute, Amsterdam, Netherlands
Background: A 70-gene tumor expression profile was established as a powerful predictor of disease outcome in breast cancer patients. The test known as MammaPrint was recently validated in independent cohorts and implementation was shown to be feasible in community hospitals. According to most clinical guidelines, small size breast cancer are identified to be at lower risk for developing distant metastasis. In this study, we investigate the performance of MammaPrint in patients with small tumors.
Design: 13 patients with small tumors (< 2cm) treated at the Hospital of Bamberg were examined by traditional clinicopathological factors (angioinvasion and immunohistochemical investigation for estrogen, progesterone and Her-2 receptor) and risk assessment was compared to MammaPrint results. To assess the accuracy of MammaPrint risk classification in this patient group, we determined MammaPrint results and outcome in patients with tumors smaller than 1 and 2 cm using 319 samples derived form publicly available data sets.
Results: The analysis of the 13 tumors showed that 2 tumors belonged to the low-risk-group, 6 to the intermediate and 5 to the high-risk-group according to the St Gallen criteria. MammaPrint confirmed the clinical low- and high-risk-cases and classified 3 of the intermediate tumors as low-risk and the other 3 as high-risk-cases. In the retrospective analysis, Kaplan Meier analysis of the 319 tumors showed a significant separation in the probability of developing distant metastases at 10 years according to MammaPrint outcome. In the 280 patients with tumors between 11 and 20 mm, the probability of remaining free of distant metastasis at 10 years was 85% in the group with good prognosis signature (44% of patients) and 60% in the group of patients with the poor prognosis signature. Moreover, even in the very small tumors (< 1cm), a high risk group with poor outcome could be identified.
Conclusions: MammaPrint provides more accurate information on recurrence risk in small tumors as compared to conventional clinical criteria and will improve the guidance for the requirement of adjuvant therapy for woman diagnosed with breast cancer. Especially, MammaPrint accurately classifies tumors with intermediate risk for progress into low- and high-risk-cases.
Wednesday, March 11, 2009 1:00 PM
Poster Session VI # 18, Wednesday Afternoon