Among these genes with significantly altered copy numbers between CUP and primary tumours, a significant amplification of TERT promoter was observed in both CUP and non-small cell lung cancer samples compared to glioma and breast primary tumours suggesting that copy number variation of TERT may play a diagnostic role for the identification of the origin of CUP tumours (Fig. 4D). The gene discussed is TERT; the disease is central nervous system cancer.