We chose not to include, for example, p53 or HER2, both of which have been studied extensively, but which have not been found consistently useful as independent predictors of outcome in early breast cancer (Pharoah et al, 1999; Mirza et al, 2002; Schlotter et al, 2003), although they may be more accurate for node-positive cases (Sjogren et al, 1998; Pharoah et al, 1999) Cyclin E, currently exciting much interest (Keyomarsi et al, 2002; Loden et al, 2002), was, perhaps incorrectly, excluded on the grounds that its expression was related to that of p27 (Porter et al, 1997). This evidence concerns the gene CCNE1 and breast cancer.