NEW YORKComputed tomography (CT) screening for lung cancer has revealed subtypes of nodules whose natural histories are being assessed in long-term follow-up, according to Claudia I. Henschke, PhD, MD, director, Division of Chest Imaging, and professor of radiology, Weill Medical College, Cornell University.
Classification is based on the extent to which the parenchyma within the nodule is obscured. "If it’s totally obscured, it’s solid. If it’s partially obscured, it’s part-solid, and otherwise, it’s nonsolid," she said at the 7th International Conference on Screening for Lung Cancer.
The first 1,000 baseline screens at her institution and New York University identified 233 nodules, she said. Of these 189 were solid, 16 part-solid, and 28 nonsolid. Among the 136 nodules that were 1 to 5 mm in size, 127 were solid, 2 part solid, and 7 nonsolid.
Cancer was detected in 27 cases, or 12% of the 233 nodules. The distribution included 14 solid nodules, 8 part-solid, and 5 nonsolid. No new cancers have been discovered in solid nodules in follow-up since the baseline screening in 1998, Dr. Henschke reported.
With solid nodules, she said, growth assessment within 3 months proved diagnostically reliable. "But that’s not quite the same for the part-solid and the non-solid lesions," she said. Five additional malignancies have been diagnosed in these subtypes, two in part-solid nodules and three in nonsolid.
In one patient, a high-resolution scan of a 15-mm part-solid nodule identified at baseline prompted recommendation of a biopsy of what was considered a stage I cancer. The patient declined and went to other institutions for other tests. "By the time there was clear evidence of growth, it was 4 years later," Dr. Hen-schke reported, "and at that point the tumor was stage IV." The cancer was identified as adenocarcinoma.
Another patient with a 10-mm part-solid nodule also initially refused to have a biopsy but had one 2 years later. The stage IA adenocarcinoma was resected.