Lung cancer is the commonest cancer in the world with the highest incidence of death. There were approximately 2.09 million new cases reported worldwide and 1.76 million deaths caused by lung cancer in 2018 (International Agency for Research on Cancer, World Health Organization). According to the Malaysian National Cancer Registry (2007 – 2011), it was reported that there were 10,608 lung cancer cases out of the total 103,507 cancer cases, with 7,415 cases in male and 3,193 cases in females.
Lung cancer is caused by mutated cells in the lungs that grew out of control, forming a tumour. In many cases, these altered cells die or are attacked by the immune system. But some cells escape the immune system and grow out of control, forming a malignant tumour in the lung.