To assess whether low-dose spiral CT screening for lung cancer in periodic health examination can contribute to detecting small and early cancers, and subsequently decrease mortality.
Starting April 1998, 11,405 individuals (9,268 men, 2,137 women; range 50–69 years; average age, 57 years) underwent first baseline low-dose spiral CT. Low-dose spiral CT parameters were 120kV,50mA,10-mm collimation, and 2:1 pitch. Each CT was read cases with independently by two radiologists and a physician. The findings were classified as follows: 1) normal, 2) abnormal but of little clinical significance, 3) abnormal with some clinical significance, 4) suspicion of lung cancer, 5) non-cancerous but suspicious active lung lesion. When the two readers could not reach consensus, the final decision was made at a weekly conference. Detailed CT examination was performed at our center for suspicion of lung cancer.
Of 11,405 individuals, 7,944(69.7%) were classified as normal; 728(6.4%) as suspicion of lung cancer; 2,733(23.9%) as other abnormal. As a result of detailed CT examination, lung cancer was strongly suspected in 123. Thoracotomy (including video-assisted thoracic surgery) was performed on 85 patients and lung cancer was diagnosed in 71. This corresponds to 0. 465% of 11,405 first screened. Forty-eight(89%) of the 54 tumors were Stage I (one had double lung cancers). Histologically, 39 were well differentiated adenocarcinoma, ten were moderately differentiated adenocarcinoma, two were poorly differentiated adenocarcinoma, two were large cell carcinoma, and one was carcinoid. With a similar method and diagnostic standard, annual repeat screening was performed on 21,342 cases, and lung cancer was diagnosed in 18. The detection rate markedly decreased and was 0.084% of 21,342. However, all(100%) of the 18 tumors were Stage I. Histologically, 8 were well differentiated adenocarcinoma, eight were moderately differentiated adenocarcinoma, two were moderately differentiated squamous cell carcinoma.CONCLUSIONS: Low-dose spiral CT screening can contribute to detecting small and early cancer.
Low-dose spiral CT is a potentially useful screening method in the detection of early lung cancer.
T. Nakagawa, None.