A recent study exploring the growing need to improve existing molecular techniques and incorporate Tumour Microenvironment (TME) traits, especially in BC patient groups with worse prognoses, including ER/HER2 and HER2+ patients also concluded that the field of gene expression-based forecasting models is growing, supported by the clinical efficacy of these multigenic tests which has been validated and is robust, with realized benefits [153]. The gene discussed is ERBB2; the disease is breast cancer.