In terms of the potential economic costs and benefits associated with the addition of this biomarker test into clinical practice, it is known that about 60 patients per million population per year present with HER2-positive breast cancer and these are routinely treated with trastuzumab (some indication as to the prevalence of PRPF38B alone and in combination with ERBB2 (Her2) is given in Supplementary Table 2). This evidence concerns the gene ERBB2 and breast cancer.