Sputum cytology
sputum is s fluid that is secreted by bronchi or tracheal cells of the lower respiratory tract. In this method, sputum is examined under a microscope and check for the presence of cancerous cells. This method is free of any risks and low cost to diagnose cancerous tissues in the lungs. This method is very limited and cannot use as a standard method to diagnose lung cancer as sputum will not always contain the cancerous cells even if cancer is present.