Molecular imaging can be used to quantify dynamic molecular changes that precede tumor size alterations and can target proliferation (fluorothymidine, [<sup>18</sup>F]-FLT), hypoxia (fluoromisonidazole, [<sup>18</sup>F]-FMISO) and HER2 expression ([<sup>89</sup>Zr]-Pertuzumab) with positron emission tomography (PET) imaging. This evidence concerns the gene ERBB2 and neoplasm.