Spiral CT Finds Early-Stage Lung Cancer

NEW YORK—Screening of smokers with helical (spiral) low-dose computed tomography (CT) is more likely than chest x-rays to find malignant tumors, and the tumors are “substantially smaller than those detected on chest radiography,” said Claudia I. Henschke, MD, of New York Presbyterian Hospital-Weill Cornell Medical Center.

Dr. Henschke and her colleagues at Cornell, New York University, and McGill University reported baseline results of the Early Lung Cancer Action Project (ELCAP), a study designed to evaluate baseline and annual repeat screening by low-radiation-dose CT in people at high risk of lung cancer.

The study has enrolled 1,000 symptom-free volunteers, aged 60 or older, with at least 10 pack-years of cigarette smoking and no previous cancer. At baseline, low-dose CT detected 233 noncalcified nodules, compared with 68 detected by chest x-ray.

Subjects with noncalcified nodules then underwent standard-dose diagnostic chest CT. Based on these findings, the researchers used an algorithm to determine the need for further diagnostic investigation. Biopsies were subsequently done on 28 of the 233 subjects with noncalcified nodules. All but one proved malignant. “Another three individuals underwent biopsy against the ELCAP recommendations; all had benign noncal-cified nodules,” Dr. Henschke said.

Further, 23 of the tumors found by low-dose CT were stage I, and all 27 tumors detected by CT were resectable. In contrast, chest x-ray found only four stage I tumors (Lancet 34:99-105, 1999).

“Although we still need longer-term follow-up of our baseline CT-detected cases of malignant disease, the high frequency of those in stage I is a strong indication that the cure rate of CT-detected disease is much higher than the current overall US cure rate of about 12%,” Dr. Henschke said.

She noted that low-dose screening CT can be done in 20 seconds and does not require IV contrast injection. “The cost is only slightly higher than that of a chest x-ray,” she said, adding that if demand for CT screening increases, cost will fall.

In an interview, Barnett Kramer, MD, deputy director of the NCI’s Division of Cancer Prevention, called the results “an important first step in evaluating an emerging technology for lung cancer screening . . . although the study was not designed to definitively prove its value in saving lives.” The NCI plans to fund studies of low-dose helical CT screening with lung cancer mortality as an endpoint, he said. He cautioned that the same sort of enthusiasm surrounded chest x-ray screening in the early 1970s, “but when put to definitive testing, it did not show a survival benefit.”