Early lung-cancer detection with spiral CT and positron emission tomography in heavy smokers: 2-year results.

BACKGROUND Low-dose spiral CT of the chest effectively detects early-stage lung cancer in high-risk individuals. The high rate of benign nodules and issues of making a differential diagnosis are critical factors that currently hamper introduction of large-scale screening programmes. We investigated the efficacy of repeated yearly spiral CT and selective use of positron emission tomography (PET) in a large cohort of high-risk volunteers. METHODS We enrolled 1035 individuals aged 50 years or older who had smoked for 20 pack-years or more. All patients underwent annual low-dose CT, with or without PET, for 5 years. Lesions up to 5 mm were deemed non-suspicious and low-dose CT was repeated after 12 months (year 2). FINDINGS By year 2, 22 cases of lung cancer had been diagnosed (11 at baseline, 11 at year 2). 440 lung lesions were identified in 298 (29%) participants, and 95 were recalled for high-resolution contrast CT. PET scans were positive in 18 of 20 of the identified cancer cases. Six patients underwent surgical biopsy for benign disease because of false-positive results (6% of recalls, 22% of invasive procedures). Complete resection was achieved in 21 (95%) lung cancers, 17 (77%) were pathological stage I (100% at year 2), and the mean tumour size was 18 mm. There were no interval lung cancers in the 2.5 years of follow-up (average time on study from randomisation to last contact), although 19 individuals were diagnosed with another form of cancer (two deaths and 17 non-fatal admissions). INTERPRETATION Combined use of low-dose spiral CT and selective PET effectively detects early lung cancer. Lesions up to 5 mm can be checked again at 12 months without major risks of progression.