Low-Dose CT Screening for Lung Cancer: Who Qualifies?

Low-dose computed tomography (LDCT) screening has been shown in randomized trials to reduce lung cancer mortality by roughly 20% in long-term heavy smokers, and is generally recommended for people meeting specific age and smoking-history criteria.

LDCT screening uses a lower radiation dose than a standard chest CT scan to look for early lung nodules before symptoms appear. Landmark randomized trials found that annual LDCT screening of long-term, heavy smokers reduced lung cancer mortality by roughly 20% compared with chest X-ray screening, establishing the evidence base for current screening guidelines.

Eligibility criteria for routine LDCT screening have been revised more than once over the past decade, generally expanding to include more long-term former smokers, not only people who currently smoke. Criteria typically consider age range and total smoking history (often measured in 'pack-years').

A significant limitation of current screening guidelines is that they are built around smoking history, which means most never-smokers — even those later diagnosed with lung cancer — are not eligible under standard criteria. This has prompted ongoing research and policy debate about whether and how to expand screening access to some never-smoker populations.