Multigene Assay In Chinese Hormone Receptor-positve Early Breast Cancer

Background: Breast cancer is now recognized as a group of disease with significant heterogeneity.Several multigene assays were developed and applied into routine practice,of which 21-gene assay had gained most plenty of clinical validity.However,the prognostic significance of 21-gene had yet not been validated in Chinese breast cancer patients.The chromodomain helicase/adenosine triphosphatase DNA binding protein 1–like gene(CHD1L)is a recently identified oncogene localized at 1q21.CHD1 L status in breast cancer and its clinical and prognostic significance remain obscure.Methods: Nine hundred and twenty-seven early breast cancer patients treated at Ruijin Hospital,Shanghai Jiaotong University,School of Medicine from 2009 to 2015 were retrospectively recruited.RT-PCR assay of 21 genes were conducted in paraffin-embedded tumor tissue to calculate the Recurrence Score(RS).Co-relations of RS and routine clinicopathologic factors were evaluated and concordances of RT-PCR and IHC tests were measured.Logistic regression were applied to determine independent predictive factors for RS.Two hundred and sixty-nine ER-positive,HER2-negative early breast cancer patients treated from 2009 to 2013 were retrospectively recruited and the relationship of RS and survival were evaluated.IHC staining for CHD1 L expression was performed on tissue microarrays containing 179 primary invasive breast cancers and 65 matched normal breast tissue specimens.Clinico-pathological features were collected and compared between different CHD1 L statuses.Kaplan-Meier curves were applied to estimate IDFS and OS.Cox regression was used to identify independent prognostic factors.Harrell’s C index and Somers’ D index were calculated to assess the accuracy of prediction of different prognostic models,and prognostic value of the models were evaluated by the change in likelihood ratio Chi square(LR-χ2).Also,RT-PCR was employed to evaluate the mRNA level expression of CHD1 L in six breast cancer cell lines.Results: Median age of 927 patients was 56 years old(range: 27~93).Seven hundred and forty-seven patients(88.6%)were demonstrated to have invasive ductal carcinoma.The median RS 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,Ki67 index and subtypes(p<0.05).Grade,PR status and Ki67 index were independent predictive factors for RS.The concordance rates between RT-PCR and IHC test were 98.7% and 87.8% for ER and PR status.Among 16 cancer-related genes of RT-PCR assay,the HER2 group and the proliferation group displayed higher correlation of single genes within groups(r>0.6).After a median follow-up of 51 months(range: 4~85),the Kaplan-Meier estimates of the rates of IDFS of 269 patients at 4 years in the low-risk,intermediate-risk,and high-risk groups were 98.7%,96.0% and 91.8%(p=0.027).The rate in the low-risk group was significantly lower than that in the high-risk group(p=0.018).In a multivariate Cox model,the RS provided significant predictive power that was independent of tumor grade and size(p=0.015).The estimates of the rates of OS at 4 years in the three groups were 100%,100% and 97.7%,with no statistically significant difference.All of the prognostic models displayed acceptable accuracy of prediction according to Harrell’s C index and Somers’ D index,while models included both clinico-pathologic factors and RS performed best in terms of prognostic value.Presence of CHD1 L over-expression was observed in 87 of the 179 patients(48.6%),which associated with a younger age(p=0.011),higher grade(p=0.004),higher Ki67 index(p=0.018)and HER2 over-expression/amplification(p=0.037).After a median followup of 55 months,patients with presence of CHD1 L over-expression had significantly poorer DFS(82.6% vs 76.3%,p= 0.035).No statistically significant difference could be found for OS between presence and absence of CHD1 L over-expression group(87.0% vs 94.9%,p= 0.439).In multivariate analysis,CHD1 L status(HR= 2.169,95% CI,1.029-4.573,p=0.042),triple negative subtype and HER2 positive subtype were identified as independent prognostic factors for IDFS.In vitro study indicated that relative mRNA expression level of CHD1 L was higher in breast cancer cell lines,especially in MDA-MB-231 and LM2-4175,when compared to normal breast epithelial cell line.Conclusions: The present study performed for the first time a large-scaled 21-gene assay among Chinese early breast cancer patients.RS correlated significantly with tumor grade,T stage,PR status,Ki67 index and subtypes.Grade,PR status and Ki67 index could independently predict RS.Results between RT-PCR and IHC test had remarkable concordance.The present study confirmed the prognostic value of 21-gene assay among Chinese ER-positive,HER2-negative early breast cancer patients.RS could provide survival prediction in addition to routine prognostic factors.Presence of CHD1 L over-expression is probably associated with aggressive tumor biology in breast cancer.CHD1 L might be a novel prognostic biomarker and a candidate factor for multigene assay for patients with breast cancer.