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.
There are two primary types of lung cancer: 1  Non-small cell lung cancer, which accounts for around 80 percent of lung cancer. 2  Small cell lung cancer, which accounts for 15 to 20 percent of lung cancers.