The chances of finding lung cancer after one and again, after two years of negative first-round tests were one in 1,000 and three in 1,000, respectively, among high-risk patients who were screened by multidetector CT in three rounds and for whom noncalcified pulmonary nodules were assessed according to volume as well as volume doubling time.
These study findings were published in the Dec. 3 issue of The New England Journal of Medicine.
The study sought to determine whether a strategy based on volume and volume-doubling time of a noncalcified nodule could be utilized as the main criteria for physicians in deciding on further action for follow-up for high-risk individuals. Rob J. van Klaveren, MD, PhD, of Erasmus Medical Center in Rotterdam, the Netherlands, and collegues wrote that they adopted a "strategy that was meant to provide an inexpensive and simple follow-up process without increasing the false-negative rate of the screening test.”
The study further proposed that CT screening may reduce mortality from lung cancer by at least 25 percent by the 10-year mark.
Utilizing software to evaluate a noncalcified nodule, growth was classified as an increase in volume of at least 25 percent in the time between two scans. A negative result was said to be found during the first round of screening if the volume of a nodule was less than 50 mm or if it was 50 to 500 mm but had not grown by the time of the three-month follow-up CT. Also, if the volume-doubling time was 400 days or more, the nodule was classified as a negative result, said the authors.
The number of participants in the study totaled 7,557, all of which were randomly assigned to either undergo 16-detector CT scanner screening in years one, two and four of the randomized trial of lung-cancer screening, or receive no screening at all.
After the first round of screening, negative screening results were found in 7,361 participants (97.4 percent) and 196 (2.6 percent) of the participants had a positive scan result. In the case of these participants, if the results were found to be lung cancer, the individual would then leave the study to be treated.
The second round of screening (one year later for participants who were not diagnosed with lung cancer) saw a 1.8 percentage rate in positive results. In the participants that experienced negative test results after the first round 20 new cases of lung cancer were detected upon two years of follow-up.
“In a population that was at an increased risk for lung cancer, our strategy of screening for lung cancer with the use of volume CT diminished the need for follow-up evaluation in participants with an indeterminate test result,” wrote van Klaveren and colleagues. “This strategy was especially useful during the second-round screening. It reduced the number of follow-up examinations in participants with a positive test result without reducing the overall sensitivity of the technique, as compared with that reported in the literature.”