Early results shed light on lung cancer screening advance

One in three smokers or former smokers screened for lung cancer at a baseline and one year follow-up visit using a recent advance in computed tomography tested positive according to a new study. Of those, 12 percent had lung biopsies, and 7 percent were diagnosed with lung cancer.

The findings, along with detailed characterizations of practiced follow-up patterns, appear in the January 1, 2005 issue of CANCER, a peer-reviewed journal of the American Cancer Society.

Low dose spiral computed tomography (LDCT) is currently being evaluated as a more effective alternative to chest radiographs for lung cancer screening through the National Lung Cancer Screening Trial (NLST). LDCT can identify small lesions than x-ray, however, studies have yet to show any improvement in lung cancer mortality using the test.

Paul F. Pinsky, Ph.D. of the National Cancer Institute in Bethesda, Maryland and his colleagues reviewed medical records pertaining to the follow-up of more than 1500 current or former smokers who received LDCT as part of the Lung Screening Study, a multi-center pilot study testing the feasibility of a large-scale nationwide trial. The researchers say 522 were found to have abnormal lung findings. Of those, 12 percent underwent biopsy, 55 percent had a follow-up CT scan but no biopsy, 12 percent were compared to prior x-ray or CT scan, 4 percent had only a clinical exam, and 3 percent received no follow-up. A total of 37 of the 522 subjects (7 percent) were diagnosed with lung cancer within a year of the first positive screen.

The investigators found that only a minority of subjects received a diagnostic work-up according to published algorithms. While biopsy was less likely the smaller the nodule size, surprisingly, the more positive LDCTs the radiologist identified, the lower the rate of the use of biopsy for diagnostic follow-up.

Also, few subjects received follow-up CT in the time commonly recommended for nodule size. For example, only 11 percent of subjects with 4-9mm nodules and 24 percent with 10+mm nodules received a follow-up CT within the recommended 4 months.

In describing the patterns of diagnostic follow-up for people with abnormal findings on LDCT, the authors conclude, the "data may be useful in estimating the potential burden and cost of CT screening and in evaluating whether practitioners are generally following reasonable procedures in their work-up of positive CT screens."