Predictive Tool Helps Clinicians Assess Lung Tumor Malignancy Probability

Predictive tools can be used to accurately estimate the probability of malignancy in lung nodules detected by low-dose screening CT scans, according to a study published in the New England Journal of Medicine.

Low-dose CT screening reduces mortality from lung cancer by 20 percent. However, the screening also discovers more nodules that require further investigation, which could include invasive diagnostic procedures, with its associated risks of complications.

Using a population-based prospective study, Canadian researchers investigated factors that could predict the probability that these lung nodules would be malignant. Such predictions could reduce the risk of morbidity and mortality from such screening programs.

Two cohorts were analyzed: a development data set comprising 1,871 patients who participated in the Pan-Canadian Early Detection of Lung Cancer Study (PanCan) and a validation set comprising 1,090 participants from British Columbia Agency (BCCA) chemoprevention trials, which were sponsored by the U.S. National Cancer Institute.  Final outcomes were nodules of any size detected by baseline low-dose CT scans. Determinants included nodule size, density, and location, previous diagnosis, family history, and demographic information (age and sex of patient).

Participants had at least one non-calcified lung nodule on the baseline low-dose CT scan. Follow-ups with repeat low-dose CT were done at three to 12-month intervals. This follow-up continued until:

·Nodules were considered to be stable for at least two years;

·Development of benign calcification;

·Nodules were no longer visible;

·Biopsy or surgical resection determined that nodules were malignant or benign.

The researchers found 7,008 nodules (102 malignancies) among the PanCan group and 5,021 (42 malignancies) in the BCCA group, for a cancer rate of 5.5 percent and 3.7 percent, respectively. Nodules in the upper lobes had a higher probability of malignancy.

“Predictive tools based on patient and nodule characteristics can be used to accurately estimate the probability that lung nodules detected on baseline screening low-dose CT scans are malignant,” the researchers concluded.