NEW YORK—Lung cancer screening investigators are sharpening their focus on the small, only partly solid nodules they observe on initial and follow-up spiral CT. Recent data show that these nodules are more often malignant than completely nonsolid or totally solid nodules, said Claudia I. Henschke, MD, PhD, chief of the Division of Chest Imaging, Weill Medical College of Cornell University.
"We want to identify which nodules have a high likelihood of malignancy. We don’t need to talk about all nodules, but tease out one subcategory, the part-solid, that needs a more aggressive workup," Dr. Henschke said at the Fifth International Conference on Screening for Lung Cancer.
Terminology in early lung cancer detection is evolving. A "nodule" refers to any focal, nonlinear opacity, of which there are two types: solid and focally translucent "subsolid" nodules (previously called "ground glass opacities" because of their appearance on CT).
Subsolid nodules can be further subdivided into those that are completely nonsolid and those that are "part-solid"—the ones that have been shown to be more frequently malignant.
In a study submitted for publication, Dr. Henschke and her colleagues found that nonsolid and solid nodules have a similar frequency of malignancy—about 18% for each. The part-solid nodules have a frequency of malignancy of approximately 60%, or a 3.5-fold higher incidence. "It’s a big difference," she said. "Therefore, the workup of those nodules in a lung cancer screening program has to be different."
Workup Only the Beginning
Workup is only the beginning. Because these part-solid nodules are found early and small, they may represent a very fertile field for chemoprevention, chemotherapy, or surgery. Rather than targeting all nodules, she said, the subsolid lesions could be singled out to more efficiently and quickly evaluate response to specific chemopreventive interventions, or in evaluations of limited resection vs lobectomy.
