Impact of Gene Expression Profiling Tests on Breast Cancer Outcomes

Abstract

Oncotype DX is furthest along the validation pathway, with strong retrospective evidence that it predicts distant spread and chemotherapy benefit to a clinically relevant extent over standard predictors, in a well-defined clinical subgroup with clear treatment implications. The evidence for clinical implications of using MammaPrint was not as clear as with Oncotype DX, and the ability to predict chemotherapy benefit does not yet exist. The H/I ratio test requires further validation. For all tests, the relationship of predicted to observed risk in different populations still needs further study, as does their incremental contribution, optimal implementation, and relevance to patients on current therapies.