Some recent studies have addressed the issue of a more refined definition of good and poor prognosis ER+ cancer, and used a modified IHC definition to include assessment of the proliferation marker Ki-67 (Cheang et al, 2009; Cuzick et al, 2009; Hugh et al, 2009), which results in a larger proportion of LB tumours with independent prognostic power (Cheang et al, 2009). This evidence concerns the gene MKI67 and cancer.