Lung cancers can be either primary or secondary. Primary is when the tumour starts to grow in the lungs first. Secondary is when it has spread from somewhere else to the lungs.5 Only primary lung cancer is discussed here.
Most lung cancers are divided into two main types: Non-Small Cell Lung Cancer (NSCLC) and Small Cell Lung Cancer (SCLC).5 Staging lung cancer is based on whether the cancer is local or has spread from the lungs to the lymph nodes or other organs. Because the lungs are large, tumors can grow in them for a long time before they are found. Even when symptoms occur, such as coughing and fatigue, people think they are due to other causes.8 For this reason, early-stage lung cancer (stages I and II) is difficult to detect.8
5. ICS. Understanding Cancer of the Lung. 2014 Edition. Available at: https://www.cancer.ie/sites/default/files/content-attachments/cancer_of_the_lung_2016_web.pdf. Accessed: 2 May 2019.
8. Lung Cancer 101. Types and Staging of Lung Cancer. Available at: https://www.lungcancer.org/find_information/publications/163-lung_cancer_101/268-types_and_staging. Accessed: 2 May 2019.