Gene Expression Profiling for Breast Cancer Prognosis

Overview and Technical Details

The American Society of Clinical Oncology recommends MammaPrint, a 70-gene signature test, to stratify early-stage breast cancer patients into low and high risk of distant recurrence, providing valuable prognostic information to complement pathology assessment and predict the benefit of adjuvant chemotherapy 1, 2
MammaPrint is intended for women 61 years of age or younger with primary invasive (Stage I or II) breast cancer who are lymph node-negative and have a tumor ≤5 cm, regardless of estrogen receptor (ER) status (positive or negative) 3, 4
The U.S. Food and Drug Administration (FDA) cleared MammaPrint in 2007 for use as a prognostic test to be used along with other clinicopathologic factors 3
Results are reported as either low risk ("13% chance to develop distant metastases at 10 years without adjuvant treatment") or high risk ("56% chance to develop distant metastases at 10 years without adjuvant treatment") 3

MammaPrint has achieved a Level of Evidence (LoE) and Grade of Recommendation (GoR) of [I, A] through the prospective MINDACT trial for its prognostic value and clinical utility in chemotherapy decision making 1, 2
The test can identify patients with an ultra-low risk of death from breast cancer at 10 or 20 years 2
MammaPrint helps determine which patients might benefit from adjuvant chemotherapy versus those who can safely avoid it, with the MINDACT trial demonstrating that women with clinically high-risk but genomically low-risk results on MammaPrint could potentially avoid chemotherapy 1, 2
The test has been shown to be cost-effective, with the OPTIMA Prelim Trial showing an 86% probability of molecular tests being cost-effective 2

The MammaPrint report states that "its performance characteristics and clinical utility in the United States Population have not been established" 3
Unlike some other tests, MammaPrint is not intended "to predict or detect response to therapy, or to help select the optimal therapy for patients" according to FDA clearance 3