Recommendations on screening for lung cancer

CMAJ 2016. DOI:10.1503 /cmaj.151421 Lung cancer is the most common cause of cancer-related deaths and the most commonly diagnosed cancer among Canadians — an estimated 26 600 Canadians were diagnosed and 20 900 died from lung cancer in 2015.1 In Canada, the incidence of lung cancer is currently higher in men than in women (although this gap is beginning to narrow), and more than 85% of cases are related to smoking tobacco. About 44% of Canadians (12.6 million) smoke or have quit smoking.2 Those with a history of heavy smoking are at the greatest risk for lung cancer. Smoking history is often measured in pack-years, which is the product of the average number of packs smoked daily and the number of years of smoking (e.g., individuals who smoked one pack a day [20 cigarettes] for 30 years, or two packs a day for 15 years, would both have a 30 pack-year history). Mortality is extremely high in late-stage lung cancer but much lower in earlier stages (5-yr relative survival rates for stage 4 and 1A lung cancer were 1% and 49%, respectively, in 2007).3 Screening for lung cancer aims to detect disease at an early stage, when it may respond better to treatment and be less likely to cause serious illness or death. Therefore, such screening has been proposed as an adjunct to other methods for reducing the burden of lung cancer, including global tobacco control initiatives and interventions designed to encourage smoking cessation.4 No organized lung cancer screening programs have been implemented in Canada.