Secondary Screening for Lung Cancer by Helical CT

We employed helical CT for secondary screening of lung cancer in the last 4 years. Out of 389 cases, 49 cases required further examinations. A total of 18 malignant tumors were detected, all of which were more than 1 cm in diameter, and in 17 cases, they were diagnosed by bronchoscopy or CT-guided needle biopsy. In the other case, the lesion increased in size during follow-up, and was diagnosed with open lung biopsy. Among the unconfirmed 31 cases, there were 10 cases with lesions which were less than 1 cm in diameter and difficult to biopsy. None of the 10 cases increased in size during follow-up. Among the 49 cases requiring further examination, 7 lesions (14%) were unclear on fluoroscopic radiographs, and 9 lesions (18%) were unclear on conventional radiographs. In all malignant cases, the lesions were detectable on both types of radiographs. In most cases, if a lesion is too small to enable a bronchoscopic or needle biopsy, follow-up is recommended rather than open lung biopsy or thoracoscopy. The effectiveness of secondary screening for lung cancer by helical CT was unclear, because all malignant tumors detected by helical CT were detected by fluoroscopic and conventional radiographs.