Low dose CT screening for lung cancer

The head of NHS England, Simon Stevens, recently announced plans to expand pilot schemes offering lung cancer screening in supermarket car parks. This has prompted inevitable questions about national screening for a cancer that causes more deaths in developed countries than breast and bowel cancers combined.
Lung cancer is curable if found at an early stage, but two thirds of people present with advanced disease, when survival is short and cure uncommon. Established screening programmes for breast and bowel cancer exist in many developed nations, but only the US and Canada have approved national screening for lung cancer with low dose computed tomography (CT), based primarily on findings from the US National Lung Screening Trial.
The trial reported reductions in mortality from both lung cancer and all causes (20% and 6.7% respectively) after annual CT for three years compared with annual chest radiography. The final results from the only other clinical study powered to detect a reduction in mortality, the Dutch-Belgian NELSON trial, are still awaited.