Background: The Early Lung Cancer Action Project (ELCAP) was designed to evaluate the usefulness of annual computed tomography (CT) screening for lung carcinoma. With the baseline results having been reported previously, the focus of the current study was on the early results of the repeat screenings.
Methods: A cohort of 1000 high-risk individuals was recruited for baseline and annual repeat CT screening. At last follow-up, a total of 1184 annual repeat screenings had been performed. A positive result from the screening test was defined as newly detected, one to six noncalcified pulmonary nodules with interim growth. The diagnostic workup of the individuals was guided by recommendations supplied by the ELCAP investigators to the collaborating clinicians.
Results: Of the 1184 repeat CT screenings, the test result was positive in 30 (2.5%). In 2 of these 30 cases, the individual died (of an unrelated cause) before diagnostic workup and the nodule(s) resolved in another 12 individuals. In the remaining 16 individuals, the absence of further growth was documented by repeat CT in 8 individuals and further growth was documented in the remaining 8 individuals. All eight individuals with further nodular growth underwent biopsy and malignancy was diagnosed in seven. Six of these seven malignancies were nonsmall cell carcinomas (five of which were Stage IA and one of which was Stage IIIA) and the one small cell carcinoma was found to be of limited stage. The median size dimension of these malignancies was 8 mm. In another two subjects, symptoms prompted the interim diagnosis of lung carcinoma. Neither of these malignancies was nodule-associated but rather were endobronchial; one was a Stage IIB nonsmall cell carcinoma and the other was a small cell carcinoma of limited stage.
Conclusions: False-positive screening test results are uncommon and usually manageable without biopsy; compared with no screening, such screenings permit diagnosis at substantially earlier and thus more curable stages. Annual repetition of CT screening is sufficient to minimize symptom-prompted interim diagnoses of nodule-associated malignancies.
Copyright 2001 American Cancer Society.