Lung cancer is a cancer of the lungs characterised by the presence of malignant tumours. Most commonly it is bronchogenic carcinoma (about 90%). Lung cancer is one of the most lethal of cancers worldwide, causing up to 3 million deaths annually. Only one in ten patients diagnosed with this disease will survive the next five years. Although lung cancer was previously an illness that affected predominately men, the lung cancer rate for women has been increasing in the last few decades, which has been attributed to the rising ratio of female to male smokers.