Comparison of HER-2 and Hormone Receptor (HR) Status between Primary Breast Cancer and Corresponding Distant Metastatic Sites with Double Check Assessment
Isabel Frahm, Sandra Sarancone, Gabriela Acosta Haab, Valeria Caceres. Sanatorio Mater Dei, Buenos Aires, Argentina; Laboratorio Quantum, Rosario, Argentina; Instituto Maria Curie, Buenos Aires, Argentina; Productos Roche, Buenos Aires, Argentina
Background: Although the vast majority of breast cancer carcinoma maintains the same biological features at relapse, recent studies suggested that some lesions may have a change in HER2 and HR status during tumor progression. As such, it may be advisable to biopsy metastatic disease for optimal treatment planning
Aim: to compare HER2 and HR status of metastatic breast cancer with those of the original tumor with simultaneously double check assessment to reduce analytical procedures errors.
Design: From December 2008 to September 2011, 137 patients with biopsy proven relapses were identified. HER-2 analysis was performed in both primary and metastasis material. Results were interpreted as ASCO/CAP guideline's. Discordant cases were evaluated by fluorescence in situ hybridization (FISH) too. ER and PR were also screened by IHC analyses.
Results: 137 primary breast cancer tumors and their corresponding distant metastasis were analyzed. Among paired primary/metastatic tumors, we found 18 discordant cases, 10 in ER or PR, and 7 in HER 2 showed discordance by IHQ and FISH.
Results are summarized in Table 1.