Molecular characteristics and metastasis predictor genes of triple-negative breast cancer.

Abstract

1043 Background: Triple-negative breast cancer(TNBC) is a subtype of breast cancer with aggressive tumor behavior and distinct disease etiology. Due to the lack of an effective targeted medicine, treatment options for triple-negative breast cancer are few and recurrence rates are high. Although various multi-gene prognostic markers have been proposed for the prediction of breast cancer outcome, most of them were proven clinically useful only for estrogen receptor-positive breast cancers. Reliable identification of triple-negative patients with a favorable prognosis is not yet possible. Methods: Clinicopathological information and microarray data from 157 invasive breast carcinomas were collected at National Taiwan University Hospital from 1995 to 2008. Gene expression data of 51 triple-negative and 106 luminal breast cancers were generated with oligonucleotide microarrays. A prognostic 45-gene signature for triple-negative breast cancer was identified using Student’s t test and receiver operating characteristic analysis. Results: Hierarchical clustering analysis revealed that the majority (94%) of triple-negative breast cancers were tightly clustered together carrying strong basal-like characteristics. A novel 45-gene signature giving 98% predictive accuracy in distant metastasis recurrence was identified in our triple-negative patient cohort. External validation of the prognostic signature in an independent microarray dataset of 59 early-stage triple-negative patients also obtained statistical significance (hazard ratio 2.29, 95% CI 1.04-5.06, Cox P = 0.04), outperforming five other published breast cancer prognostic signatures. The prognostic signature was statistically predictive with the node-negative triple-negative patients in the validation cohort. Conclusions: The 45-gene prognostic signature identified in this study revealed that TGF-β signaling in immune/inflammatory regulation may be critically involved in distant metastatic invasion of TNBC. The 45-gene signature, if further validated, may be a clinically useful tool in risk assessment of metastasis recurrence for early-stage triple-negative patients.