Interior of the cecum and lower end of ascending colon with the ileocecal valve labeled as colic valve. Endoscopic image of cecum with arrow pointing to ileocecal valve in foreground.
Lung cancer is a malignant tumour that starts in the cells of the lung. Malignant means that it can spread, or metastasize, to other parts of the body. When cancer starts in lung cells, it is called primary lung cancer. The lung is part of the respiratory system. You use your lungs when you breathe.
Lung cancer is a disease in which abnormal (malignant) lung cells multiply and grow without control. These cancerous cells can invade nearby tissues, spread to other parts of the body, or both. The two major kinds of lung cancer are named for the way the cells look under a microscope. They are: