Clinical Citations: Using spiral CT and PET scans to facilitate early detection of lung cancer

Although lung cancer screening has been controversial, recent evidence suggests that a protocol based on the use of spiral CT can facilitate early detection. The addition of F-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) scanning to the screening protocol can help minimize unnecessary invasive procedures for benign lesions without increasing the risk of missed malignancies.

Bastarrika and associates studied 911 high-risk persons who underwent spiral CT scanning of the chest. The participants were at least 40 years of age and were current or former smokers who had at least a 10-pack-year smoking history. Follow-up CT scans were ordered in persons with noncalcified nodules of 5 mm or larger. FDG-PET was performed in persons with nodules of 10 mm or larger and in those with smaller (more than 7 mm) nodules that were growing. If findings on the initial CT scan were negative, screening was repeated after 12 months.

Of the 911 persons in whom CT was performed at baseline, 14% had noncalcified nodules of 5 mm or larger and 3.6% had nodules of 10 mm or larger. Eleven non-small-cell lung cancers (NSCLCs) and one small-cell lung cancer were detected in the baseline study, yielding a prevalence rate of 1.32%. Two NSCLCs were detected during follow-up. All NSCLCs were diagnosed in stage I.

FDG-PET helped make the diagnosis in 19 of 25 indeterminate nodules. The sensitivity, specificity, positive predictive value, and negative predictive value of FDG-PET were 69%, 91%, 90%, and 71%, respectively. The sensitivity and negative predictive value of the screening algorithm were both 100%.