Aims IHC4 score, based on expression of four routine markers (oestrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and proliferation marker, Ki67), is a recently developed, cost-effective prognostic tool in breast cancer. Possibly, the score may be useful also in advanced diseases where only core needle biopsy (CNB) is available and neoadjuvant therapy. However, its studies on CNB are scant. This study examined whether IHC4 score assessment on CNB is comparable to that from whole section (WS).
Methods Immunohistochemical (IHC) analysis was performed for ER, PR, HER2 and Ki67 on 108 paired CNB and WS to evaluate IHC4 score (with follow-up range 1–230 months and 5 relapse/death). Concordance between the two was examined. Factors that affected the concordance were analysed. Additionally, IHC4 score was compared with Nottingham Prognostic Index (NPI).
Results There was moderate concordance between IHC4 score on CNB and WS (all cases: κ=0.699, p<0.001; ER+ cases: κ=0.595, p<0.001). Among the IHC4 components, concordance for HER2 was the poorest (κ=0.178, p<0.001 in all cases; ER+ cases: κ=0.082, p<0.097). Significant factors affecting concordance between CNB and WS included number of cores, total core length and percentage of tumour cells in cores (p≤0.030), indicating the importance of sufficient sampling. Interestingly, the concordance was also affected by patients’ age (p=0.039). There was poor agreement between IHC4 score and NPI (κ≤0.160).
Conclusion Our results suggested that IHC4 score can be used on adequately sampled CNB. Its poor agreement with NPI highlights the independence of the two factors.
- breast cancer
- core needle biopsy
- whole section
- IHC4 score
- Nottingham Prognostic Index
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Handling editor Cheok Soon Lee.
Contributors ML performed the experiment and wrote the paper. SXT and YJS collected the samples and performed the experiments. JYST analysed the data and wrote the paper. YBN and BKBL collected and arranged clinicopathological data of cases. GMKT conceived the idea for the paper, provided guidance and critically revised the paper. All authors read and approved the final version to be published.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent Not required.
Ethics approval Joint Chinese University of Hong Kong-New Territories East Cluster Clinical Research Ethics Committee.
Provenance and peer review Not commissioned; externally peer reviewed.
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