Intrinsic Subtypes and Gene Expression Profiles in Primary and Metastatic Breast Cancer

In this study, we compared intrinsic molecular subtypes and gene expression in 123 paired primary and metastatic tissues from breast cancer patients. Intrinsic subtype was identified using a PAM50 classifier and χ2 tests determined the differences in variable distribution. The rate of subtype conversion was 0% in basal-like tumors, 23.1% in HER2-enriched (HER2-E) tumors, 30.0% in luminal B tumors, and 55.3% in luminal A tumors. In 40.2% of cases, luminal A tumors converted to luminal B tumors, whereas in 14.3% of cases luminal A and B tumors converted to HER2-E tumors. We identified 47 genes that were expressed differentially in metastatic versus primary disease. Metastatic tumors were enriched for proliferation-related and migration-related genes and diminished for luminal-related genes. Expression of proliferation-related genes were better at predicting overall survival in metastatic disease (OSmet) when analyzed in metastatic tissue rather than primary tissue. In contrast, a basal-like gene expression signature was better at predicting OSmet in primary disease compared with metastatic tissue. We observed correlations between time to tumor relapse and the magnitude of changes of proliferation, luminal B, or HER2-E signatures in metastatic versus primary disease. Although the intrinsic subtype was largely maintained during metastatic progression, luminal/HER2-negative tumors acquired a luminal B or HER2-E profile during metastatic progression, likely reflecting tumor evolut...

Source: Cancer Research - April 30, 2017 Category: Cancer & Oncology Authors: Juan M. Ceȷalvo, Eduardo Martinez de Duenas, Patricia Galvan, Susana Garcia–Recio, Octavio Burgues Gasion, Laia Pare, Silvia Antolin, Rosella Martinello, Isabel Blancas, Barbara Adamo, Angel Guerrero–Zotano, Montserrat Munoz, Paolo Nuci Tags: Clinical Studies Source Type: research