The IHC4+C score: an affordable and reproducible non-molecular decision-aid in hormone receptor-positive breast cancer. Does it still hold value for patients in 2020?

IHC4 and COMBINE scores for enhanced prognostic stratification in HR+/HER2- breast cancer patients after neoadjuvant chemotherapy

BACKGROUND

The prognostic value of pathological complete response (pCR) in HR+/HER2- breast cancer patients following neoadjuvant chemotherapy (NAC) is limited, as many of these patients achieve long-term survival regardless of pCR status. The effectiveness of current tools-residual cancer burden (RCB), the Miller-Payne (MP) score, CPS-EG score and the immunohistochemical 4 (IHC4)-in this subgroup remains uncertain. In this study, we validated the prognostic role of these approaches and developed a COMBINED score capable of more accurately stratifying patients into distinct risk groups, effectively identifying low-risk patients with favorable outcomes who may be suitable for treatment de-escalation.

METHODS

This study retrospectively analyzed 601 HR+/HER2- breast cancer patients at Sun Yat-sen Memorial Hospital who did not achieve pCR following NAC. Patients were stratified using the IHC4, RCB, MP, CPS-EG, and a novel COMBINE score (integrating CPS-EG and IHC4). Survival outcomes, including disease-free survival (DFS) and overall survival (OS), were evaluated using Kaplan-Meier analysis and Cox regression, with time-dependent ROC and concordance index (C-index) calculations to assess prognostic performance.

RESULTS

The IHC4 and CPS-EG scores outperformed the RCB and MP scores in predicting DFS and OS for non-pCR HR+/HER2- patients. The COMBINE score further enhanced prognostic accuracy, stratifying patients into four risk groups with significant differences in 5-year DFS (96.5% for low-risk vs. 55.1% for high-risk) and OS (100% for low-risk vs. 63.4% for high-risk). The COMBINE score consistently demonstrated superior AUC and C-index values compared to the CPS-EG and IHC4 scores individually at all time points (all p-values < 0.05).

CONCLUSION

The IHC4 score adds prognostic value beyond the CPS-EG score in HR+/HER2- breast cancer patients post-NAC. The COMBINE score, integrating both systems, offers superior prognostic stratification, highlighting the importance of combining clinical staging with tumor biology. Future studies with independent datasets are needed to validate these findings. This study provides valuable insights for optimizing treatment decisions in HR+/HER2- breast cancer.

The Role of Nodes and Nodal Assessment in Diagnosis, Treatment and Prediction in ER+, Node-Positive Breast Cancer

The majority of breast cancers are oestrogen receptor-positive (ER+). In ER+ cancers, oestrogen acts as a disease driver, so these tumours are likely to be susceptible to endocrine therapy (ET). ET works by blocking the hormone's synthesis or effect. A significant number of patients diagnosed with breast cancer will have the spread of tumour cells into regional lymph nodes either at the time of diagnosis, or as a recurrence some years later. Patients with node-positive disease have a poorer prognosis and can respond less well to ET. The nodal metastases may be genomically similar or, as is becoming more evident, may differ from the primary tumour. However, nodal metastatic disease is often not assessed, and treatment decisions are almost always based on biomarkers evaluated in the primary tumour. This review will summarise the evidence in the field on ER+, node-positive breast cancer, including diagnosis, treatment, prognosis and predictive tools.

The World Health Organization Classification of Tumors and External Quality Assurance for Immunohistochemistry and Molecular Pathology

CONTEXT.—

This article is based on a talk given by the lead author at the Eigth Annual Princeton Integrated Pathology Symposium: Breast Pathology, on Sunday, April 11, 2021.

OBJECTIVE.—

To show how the World Health Organization (WHO) Classification of Tumours links to the requirements for quality assurance in breast pathology, including both immunohistochemistry and molecular pathology.

DATA SOURCES.—

The WHO Classification of Tumours 5th edition Breast Tumours entries formed the basis of the talk, together with guidance published by the International Quality Network for Pathology.

CONCLUSIONS.—

The WHO Classification of Tumours provides a definitive set of international standards for tumor diagnosis contributed by experts, based on available clinical and research evidence. Techniques used in pathology need internal and external quality assurance to ensure accurate reports for patient management.