How is lung cancer screening defined? The UK National Screening Committee defines ‘screening’ as a process of identifying people who are healthy but at increased risk of developing a disease. In the case of cancer screening, this means detecting early cancer in asymptomatic people and providing more effective treatment accordingly. There are currently three active NHS cancer screening programmes in the UK: cervical cancer, breast cancer and bowel cancer. Background on lung cancer screening There are four types of screening tests for lung cancer: imaging, bronchoscopy, sputum testing, and biochemical markers of serum and other body fluids. To date, studies have shown that only CT screening can reduce lung cancer mortality. Biochemical markers and genetic techniques The detection of early lung cancer through biochemical studies and identification of genomic abnormalities is progressing very fast, but there are no clinical trials showing that blood, sputum or breath tests can effectively diagnose early lung cancer. Biochemical markers may be of interest in situations such as risk stratification, identifying which patients should be further examined, and which patients need further study. It is increasingly recognized that different lung tumors have different genomic abnormalities, which can be helpful for targeted and individualized treatment, but there is no evidence yet that it is meaningful for early detection and diagnosis of lung cancer. 2. Chest X-ray The role of chest X-ray for early diagnosis of lung cancer was very much emphasized in the 1950s to 1970s, as several studies showed that X-ray could detect early lung cancer and that patients on inspection teams could gain survival benefit. However, prostate, lung, ovarian and colorectal screening trials showed that chest X-rays did not reduce lung cancer mortality. With the advancement and widespread use of CT, recent clinical trials have adopted CT as a lung cancer screening tool. However, great attention should be paid to the bias present in screening trials before analyzing the results.