<qa>  What is the size of the tissue that is too small to retrieve?II. Patients without actionable gene alteration or mutations in tissue at screening phase III. Patients who cannot tolerate anti-cancer therapy for at least 2 months should be withdrawn IV. Patients who cannot cooperate the imaging study for response evaluation of anti-cancer therapy V. Patients tissue is too small to retrieve for NGS analysis. VI. Difficult blood sampling. VII. Clinicians judgement. 