EGFR and prostate cancer: Genotypic heterogeneity regarding gene mutations (e.g. in p53, KRAS, PIK3CA) and gene amplifications (e.g. EGFR, HER2, leucine-rich g-protein receptor 5, Aurora A kinase and androgen receptor) could be observed in individual CTCs from colon4, 11, breast6 and prostate cancer patients33.