Sputum is coughed up from the lungs. Then some of it is put under a microscope to see if there are any abnormal cells. This test is useful for finding tumors that may be growing in the airways of the lungs.12
12. ACS. Tests for Non-Small Cell Lung Cancer. Available at: https://www.cancer.org/cancer/non-small-cell-lung-cancer/detection-diagnosis-staging/how-diagnosed.html. Accessed 2: May 2019.