In a new study entitled “CT Screening for Lung Cancer: Nonsolid Nodules in Baseline and Annual Repeat Rounds,” researchers at Mount Sinai School of Medicine show CT scans can safely monitor people with non-solid lung nodules and assess with time their risk to develop cancerous nodules. The study was published in the journal Radiology.

Lung nodules can arise in lungs due to infections or fibrosis, but also as a sign of a more serious disease, lung cancer. These nodules are visible in computed tomography (CT) scans and can appear as solid, part solid or nonsolid masses. Since these nodules can have a benign or malignant origin, screening and management of these masses is critical for adequate interventions, if needed. This is particularly challenging with nonsolid nodules.

As explained by Claudia I. Henschke, Ph.D., M.D., at the Department of Radiology at Mount Sinai School of Medicine, New York City and a co-author in the study “Nonsolid nodules could be due to inflammation, infection or fibrosis, but could also be cancerous or a precursor of cancer. For screening, we have to define which nodules need further workup and how quickly we have to do that workup.”

In this study, researchers at Mount Sinai School of Medicine and colleagues analyzed the CT scans from participants of the International Early Lung Cancer Program (I-ELCAP), in total 57,496 participants. With the objective of reducing lung cancer-induced deaths, I-ELCAP participants receive CT screening at baseline recruitment, and are then repeated annually. For this study, the team determined the prevalence of non solid nodules and their effect on patients’ long-term outcomes.

The team identified non-solid nodules in 4.2 percent (2,392 cases) of the screenings at baseline. From these, 73 cases resulted in a cancer diagnosis. New nodules were identified in 485 (0.7 percent) cases from the annual repeating screening, with 11 cases having a diagnosis of cancer (but still on stage I). In 22 cases, the nonsolid nodule developed a warning sign characteristic of a cancerous phenotype – transiting from non-solid to a solid nodule – in 22 cases (before any treatment, usually surgery). Notably, the transition from nonsolid to solid occurs in more than two years and no new nodules of 15 cm diameter (or higher) developed into cancer.

The results suggest that non-solid nodules (independently of their size) can be safely monitored with a low-dose CT, to be performed annually, as a monitoring screening strategy to identify those transiting to a solid nodule and, hence, to a tumorigenic state.

“The results show that if we see a nonsolid lung nodule of any size, we can tell people to come back in one year for another CT. These findings are important for reducing unnecessary CT scans and possible biopsies or surgery in programs of CT screening for lung cancer,” commented Dr. Henschke.

Study co-author David F. Yankelevitz, M.D. added, “Many recommendations had been fairly aggressive with respect to nonsolid nodules. These results show that there is no reason to be aggressive in pursuit of cancer, so long as the nodules stay in this nonsolid form. This is a major step forward for lung cancer screening protocols. It will help us cut down on the number of surgeries and unnecessary imaging tests.”