For example, in lung cancer, the EGFR gene copy number (GCN) or mutations (especially EGFRT790M) has been confirmed to be related to the resistance of molecule-targeted drugs [20, 21]; in the latest molecular-detection guideline of lung cancer, the importance of both EGFR GCN and mutations detection before the targeted treatment is reiterated [22]. The gene discussed is EGFR; the disease is lung carcinoma.