Abstract P1-05-24: A head-to-head comparison of paraffin-embedded MammaPrnt versus oncotype DX: A Mcgill University Healh Center experience

Abstract

Abstract Background: Breast cancer is the most common malignancy among women. With the introduction of improved imaging techniques and the general population's awareness of breast cancer, increasing numbers of patients are more frequently diagnosed at a very early stage. The Oncotype DX Recurrence Score (ODX) is commonly used to estimate recurrence risk and chemotherapy benefit in ER positive, node negative breast cancer. Earlier studies showed that women with Oncotype DX Recurrence score results of 11 or less had excellent outcomes which proved that thousand of patients worldwide can forgo chemotherapy and its harmful side effects based on a low Recurrence score. Now another test called the Mammaprint has been approved by the United States (US) Food and Drug Administration to assess the risk of cancer relapse. The primary study objective was to evaluate the concordance of patient results with Oncotype Dx (ODX) when compared to the 70-gene signature Mammaprint (MP), the 80-gene signature of BluePrint (BP) and TargetPrint (TP) Methods: This retrospective clinical study was carried out in the Oncology Department at the Royal Victoria Hospital (RVH), part of the MUHC. Eighty-six consecutive patient-slides node negative hormone positive breast cancer tissue tested with the Oncotype DX between October 2008 and September 2014 were included. Further inclusion criteria were age > 18. These same slides were then analyzed and classified with MammaPrint as low or high risk by Agendia Laboratories. BluePrint (BP) and TargetPrint (TP) analysis were also performed by Agendia Laboratories. Results: Of the 16 ODX RS between 0 and 11, 13 were low risk by MP (81 % agreement) and 16 were low risk by BP (100% agreement). Of the 50 ODX low RS cases, 33 were low risk by MP (66 % agreement) and of the 9 ODX high RS, 7 were high risk by MP (78 % agreement). Of ODX intermediate risk cases (27), 14 of were MP low risk (52 %), (48 %) 13 were MP high risk. Of BP low risk luminal tumors, 33/49 (67%) were ODX low, 14/49 (29%) ODX intermediate, and 2/49 (4%) ODX high risk. BP class was correlated with ER, PR and HER2 results. Overall agreement between clinical ER, PR, HER2 (IHC+FISH) results with TP results were 98% (81/83), 83% (69/83), 99% (82/83), and percent positive agreement for HER2 was 0/1 (of unequivocally HER2 positive cases identified correctly by TP). Conclusion: Our results show that there is a high concordance between ODX RS of 11 or less and low risk Mammaprint and Blueprint scores. When the ODX RS is above 11, our study shows that there are real differences in risk stratification between MP and ODX. At this point, there is no consensus seen when Oncotype DX is above 11. Citation Format: Desforges P, Saleh R, Nathaniel B. A head-to-head comparison of paraffin-embedded MammaPrnt versus oncotype DX: A Mcgill University Healh Center experience [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-05-24.