A variety of proven and putative predictive markers (for example, ER, PgR, ploidy, S-phase, HER2, p53, and other oncogenes and growth factors) have been evaluated in previous studies [19] in material obtained from fine-needle biopsies and core-cut biopsies, and have been correlated with the tumour response in order to assess whether unnecessary surgical or radiological treatment can be avoided after systemic therapy, or even whether systemic treatment can be avoided entirely. The gene discussed is ESR1; the disease is neoplasm.