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Incorporating volumetric data on noncalcified lung nodules from CT scans may improve screening strategies for patients at high risk for lung cancer, data from a large randomized trial suggest.

Adding CT-derived, on-lesion volume and growth resulted in a sensitivity of 94.6% and negative predictive value of 99.9% after the first of three screening CT scans.

Among patients with a negative baseline lung CT scan, the probability of developing lung cancer was zero at three months, one in 1,000 at one year, and three in 1,000 at two years.

"In the 7,361 subjects with a negative screening result in round one, 20 lung cancers were detected after two years of follow-up," Rob J. van Klaveren, MD, PhD, of Erasmus Medical Center in Rotterdam, the Netherlands, and colleagues reported in the Dec. 3 issue of the New England Journal of Medicine.

"As an absolute standard for negative test results, we used the absence of lung cancer after two years of follow-up, a period that is considered to be sufficient for concluding that a nodule is benign," they added.

"The 400-day threshold for volume-doubling time that we used was based on current opinion that lung cancers with a volume-doubling time of 400 days or more are overdiagnosed cases."

Increased use of multidetector CT has increased the chance of finding noncalcified pulmonary nodules. As a result, physicians increasingly have to decide the best course of action for high-risk patients with these nodules. Most often, patients with noncalcified nodules larger than 5 mm are referred for additional testing, the authors noted.

Investigators in the ongoing Dutch-Belgian randomized lung cancer screening trial (NELSON) employed a strategy designed to provide simple and inexpensive follow-up without increasing the risk of false-negative results on screening CT.

The strategy relied primarily on the volume and volume-doubling time of noncalcified pulmonary nodules (Lung Cancer 2006; 54: 177-84).

The principal purpose of the NELSON trial was to determine whether screening CT at baseline and after one and three years reduces lung cancer mortality by 25% among high-risk patients, compared with no screening. The current report from the trial represents two-year follow-up data.

Of the 7,557 participants randomized to screening CT, 50.5% had a total of 8,623 noncalcified pulmonary nodules on the baseline CT, and 98% of the nodules were solid.

The authors reported that 5,987 participants (79.2%) had negative baseline scans, 1,451 (19.2%) had indeterminate scans, and 119 (1.6%) had positive scans.

On average, follow-up scans were obtained within 100 days of the baseline scan for patients with indeterminate findings. Inclusion of those scans increased the proportion of study participants with negative baseline scans to 97.4% (7,361) and positive scans to 2.6% (196).

Among patients with nodules, the baseline screen was considered negative if the volume was less than 50 mm3, 50 to 500 mm3 but had not grown by 25% by the three-month follow-up CT, or had grown by 25% but had a volume-doubling time of 400 days or more.

The baseline screening CT had a sensitivity of 94.6% and a negative predictive value of 99.9%. Of the 7,361 study participants with negative baseline scans, 20 had lung cancers that were detected within two years.

"The results suggest that the efficiency of the diagnostic workup for lung cancer can be improved by integrating the measurement of volume growth of lung nodules as an indicator of clinically significant lung cancer while limiting the need for additional costly or potentially harmful diagnostic procedures, " James L. Mulshine, MD, of Rush University in Chicago and David M. Jablons, MD, of the University of California San Francisco, wrote in an editorial.

Source: MedPage Today

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