[Clinical utility study of 21-gene assay in 927 Chinese patients with early breast cancer]

Objective: To investigate the distribution patterns of 21-gene assay and its influencing factors in Chinese patients with early breast cancer. Methods: Nine hundred and twenty-seven early breast cancer patients were retrospectively recruited from January 2009 to December 2015 at Ruijin Hospital, Shanghai Jiaotong University School of Medicine. The 21-gene reverse transcriptase-polymerase chain reaction(RT-PCR) assay were conducted in paraffin-embedded tumor tissues to calculate the Recurrence Score(RS). Immunohistochemistry(IHC) assay was used to measure the expression levels of estrogen receptor(ER), progesterone receptor(PR) and Ki-67. Concordances of RT-PCR and IHC results were assessed. Correlations of RS and classical clinicopathological factors were evaluated, and logistic regression were applied to determine independent predictive factors for RS. Results: The median RS of 927 patients was 23(range: 0~90), and the proportions of patients categorized as having a low, intermediate, or high risk were 26.5%, 47.7% and 25.8%, respectively. The distribution of RS varied significantly according to different tumor grade, T stage, PR status, Ki-67 index and molecular subtypes(P<0.05 for all). Grade, PR status and Ki-67 index were independent predictive factors for RS. ER, PR status and Ki-67 index showed significantly correlation between RT-PCR and IHC assays, and the concordance rates for ER and PR status were 98.7% and 87.8%, respectively. Conclusions: RS significantly correlated with tumor grade, T stage, PR status, Ki-67 index and subtypes. Grade, PR status and Ki-67 index can independently predict RS. Remarkable concordances of ER, PR status and Ki-67 index are found between RT-PCR and IHC assays.