SAN ANTONIO—Molecular tumor subtyping with BluePrintTM and MammaPrintTM offers more accurate prediction of long-term breast cancer outcomes than traditional immunohistochemistry (IHC)/fluorescent in-situ (FISH) hybridization subtyping, reported authors of a retrospective study at the 2013 San Antonio Breast Cancer Symposium.
“This study shows that molecular subtyping leads to a statistically more accurate prognostic stratification compared to clinical classification,” reported senior author Massimo Cristofanilli, MD, of Thomas Jefferson University Hospital in Philadelphia, PA, lead author Katharine Yao, MD, of the NorthShore University Health System in Evanston, IL, and their coauthors. “Luminal A patients have a 9.7 year DMFS (distant metastases-free survival) of 98% and Luminal B patients have a 9.7-year DMFS of 93% despite inclusion of five triple-negative and 14 clinically classified HER2-positive patients.”
Use of MammaPrint with the BluePrint molecular subtyping profile allows identification of patients with “marked differences in long-term outcome and response to neoadjuvant therapy,” the coauthors noted. The new study was undertaken to compare these tools’ prediction of long-term outcomes compared to traditional clinical IHC/FISH subtyping.
At a median follow-up of 9.7 years after diagnosis, molecular classification was conducted using BluePrint and MammaPrint of clinically subtyped frozen tumor tissue (n = 206) and frozen/formalin-fixed paraffin embedded (FFPE) tumor samples (n = 168) from patients diagnosed between 1992 and 2010 with T1-3, N0-1b breast cancers provided by NorthShore and the Fox Chase Cancer Center in Philadelphia, PA.
Whereas the molecular subtyping offered more subtype-specific probabilities for DMFS than clinical subtyping (P = 0.001 vs. P = 0.107, not significant, for clinical subtyping), the researchers reported.
“MammaPrint in HR-positive/HER2-negative patients only (n = 239) has a significant hazard ratio of 7.16 (95% CI: 1.52-33.76), with similar 9.7-year DMFS rates (98% low-risk, n = 147; 89% high-risk, n = 92),” they noted.
“Discordant cases are being centrally re-assessed for ER [estrogen receptor], PR [progesterone receptor], and HER2,” the coauthors noted.
The study was funded by Agendia. Agendia’s MammaPrint is the first US Food and Drug Administration–approved test for predicting recurrence risk among patients with breast cancer. Symphony is the only predictive multigene breast cancer panel based on prospective trials, including outcome data from the RASTER study, according to the company.
- Yao K, Turk M, Kaul K et al. P2-11-23. Presented at: San Antonio Breast Cancer Symposium 2013. Dec. 10-14, 2013; San Antonio.