Abstract
BackgroundAdjuvant therapy decisions may be partly based on the results of a multigene quantitative reverse transcription-polymerase chain reaction (RT-PCR)-based assay: the 21-gene recurrence score (RS) test of resection specimens. When necessary, core needle biopsy (CNB) may be considered as a surrogate. Here, we evaluated the concordance in gene expression according to results from RT-PCR-based RS testing between paired CNBs and resection specimens.MethodsCNBs and resection specimens from 50 breast cancer (BC) patients were tested to calculate RSs. First, we examined the concordance of the ER, PR and HER-2 status of tissue samples indicated by immunohistochemical (IHC) and RT-PCR analyses. Then, we compared the IHC findings of ER, PR, HER-2 and Ki-67 staining across paired samples. Ultimately, the RS and single-gene results for ER, PR, HER-2 and Ki-67 were explored between paired samples.ResultsThe concordance between IHC and RT-PCR was 100%, 80.0% and 100% for ER, PR and HER-2, respectively, in both resection specimens and CNBs. The concordance for IHC ER, PR, HER-2 and Ki-67 status was 100%, 94.0%, 52.0% and 82.0%, respectively, between paired samples. RS results from paired samples showed a strong correlation. The overall concordance in RS group classification between samples was 74%, 72% and 78% based on traditional cutoffs, TAILORx cutoffs and ASCO guidelines, respectively. ER, PR, HER-2 and Ki-67 were modestly- to- strongly correlated between paired samples according to the RT-PCR results.ConclusionA modest- to- strong correlation of ER, PR, HER-2 and Ki-67 gene expression and RS between CNBs and resection specimens was observed in the present study. The 21-gene RS test could be reliably performed on CNBs. ER, PR and HER-2 status showed remarkable concordance between the IHC and RT-PCR analyses. The concordance between paired samples was high for the IHC ER, PR and Ki-67 results and low for HER-2.
Highlights
Breast cancer (BC) is the leading cause of death in women aged 35–55 and the second leading cause of death among women of all ages [1]
The 21-gene assay is the only validated multigene assay for predicting the response to chemotherapy according to the National Comprehensive Cancer Network (NCCN) guidelines [22]
Our study indicated that 24%, 66% and 10% of patients with available resection specimens showed low, intermediate, and high-risk recurrence score (RS), respectively, based on traditional RS cutoffs, while the proportions of patients categorized into the low, intermediate, and high-Ki-67 cancers (high RS) risk groups were 2%, 60% and 38%, respectively, according to the TAILORx RS cutoffs [41]
Summary
Breast cancer (BC) is the leading cause of death in women aged 35–55 and the second leading cause of death among women of all ages [1]. Adjuvant therapy decisions may be partly based on the results of a multigene quantitative reverse transcriptionpolymerase chain reaction (RT-PCR)-based assay: the 21-gene recurrence score (RS) test of resection specimens. We evaluated the concordance in gene expression according to results from RT-PCR-based RS testing between paired CNBs and resection specimens. Methods CNBs and resection specimens from 50 breast cancer (BC) patients were tested to calculate RSs. First, we examined the concordance of the ER, PR and HER-2 status of tissue samples indicated by immunohistochemical (IHC) and RT-PCR analyses. The 21-gene RS test could be reliably performed on CNBs. ER, PR and HER-2 status showed remarkable concordance between the IHC and RT-PCR analyses. The concordance between paired samples was high for the IHC ER, PR and Ki-67 results and low for HER-2
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