Lung Cancer Screening With Low Dose Computed Tomography: Challenging Aspects For The Clinicians

BACKGROUND: The main challenge of screening healthy population with ld-CT is to reach a delicate balance between excessive rate of diagnostic procedures (with increased radiation exposure, complications and high costs) and risk of delayed detection of malignancy with missed opportunity for definitive cure. In this frame of mind, we evaluated pitfalls, difficulties and sources of mistakes in the management of lung nodules detected in the Cosmos screening trial. METHODS: Between October 2004 and October 2005, 5202 asymptomatic high-risk individuals, underwent a screening low dose multidetector CT (ld-CT) among a single center trial. The subsequent year 4745 people underwent the annual ld-CT (92%). A protocol for the diagnostic work-up of nodules identified by ld-CT was: ld-CT at 1 year for nodules with maximum diameter less than 5 mm, repeated ld-CT at 3 to 6 months for lesions between 5.1 and 8 mm and FDG-PET for lesions larger than 8.1 mm. Surgical biopsy was deserved to PET positive or growing lesions over time. RESULTS: 88 lung cancer were identified during the first two years of screening (1.7%) in front of 101 surgical procedures. Most cases were in early stage (64 stage I, 6 stage II). A delayed detection of malignancy caused a progression of disease in two cases only (1 stage IIIA and 1 IIIB). Radical resection was achieved in 89% of cancers. Diagnosis at surgery of benign lesions occurred in 13 patients (13% of all surgical cases), most of them were chronic inflammations, hamartoma or lymphoid hyperplasia (7 false positive PET, 6 growing lesions over time). False negative PET tumors occurred in 15 (17%) patients out of 88 detected malignancies and were non- solid or less than 1 cm nodules. CONCLUSIONS: Screening ld-CT is an effective tool for the early detection of lung cancer, but the management of these detected nodules still remains a challenge in the screening process, requiring a great experience in the assessment phase, an optimization of the diagnostic work up protocol and a strict collaboration between surgeons, radiologists and nuclear medicine physicians to minimize mistakes of interpretation.