Evolution of lung nodules < or =5 mm detected with low-dose CT in asymptomatic smokers.

Low-dose CT is widely employed for the early diagnosis of lung cancer in high-risk populations even if screening programmes have not been clinically validated yet; however, the optimum follow-up schedule for small lung nodules of uncertain status has not been defined. The aim of this study was to assess outcomes for small pulmonary nodules (diameter < or =5 mm) detected by CT in asymptomatic smokers In 2000-2001, 1035 high-risk people were enrolled in an observational study for the early detection of lung cancer by yearly CT. The prevalence, incidence and evolution of small lung solid nodules are described 238 solid lung nodules < or = 5 mm were identified at initial low-dose CT in 165 people (prevalence 15.9%). 26% of them were not detected in the following 4 years, 43.3% did not change and 10.1% grew to >5 mm; three were removed and found to be malignant (all T1N0); the remaining 21 were followed yearly In the following year, 79 new small nodules were detected (incidence 7.9%). 11.4% were not detected in the subsequent 3 years, 79.7% did not change, 2.5% grew to > 5 mm and were followed yearly In conclusion, prevalent and incident nodules < or =5 mm detected by low-dose CT screening for lung cancer can be safely checked at 1 year intervals.