[Diagnosis of small peripheral lung cancers using spiral computed tomography lung cancer screening]

Small peripheral lung cancers can be detected by spiral or helical computed tomography (CT). We applied mobile spiral CT as the first step in further examination (or secondary screening) for lung cancer. We detected 86 lung cancers per 100,000 persons without spiral CT, and 102 patients with spiral CT. Using the latter method, the resection rate and the rate of early-stage lung cancer increased significantly from 48.6% to 67.3% (p < 0.01) and from 21.1% to 35.1% (p < 0.05), respectively. Good results were obtained with mobile CT, especially in women. The mean tumor size of lung cancer detectable with CT was 7 mm smaller than that detected by the previous method. The mean tumor size was only less than 20 mm in females. Overall 787 lung cancers per 100,000 persons were detected using spiral CT for primary screening (1,039 lung cancers/100,000 in men). We must investigate whether the new CT screening system for lung cancer really leads to a lower mortality rate compared with the previous methods. When small nodular lesions with ground-glass opacity could not be diagnosed, the subsequent period up to 10 months can be used to obtain a final diagnosis, regardless of their malignancy. This paper reports specific findings of small peripheral lung cancers, and review the methods of diagnosis for small-sized tumors.