Purpose: The New York-Early Lung Cancer Action Project (NY-ELCAP) was designed to evaluate the usefulness of annual CT screening for lung cancer in high-risk subjects at 12 medical institutions spanning the State of New York, including areas with endemic histoplasmosis.
Methods and Materials: Baseline screening started with an initial, low-dose chest CT performed on 6,368 men and women aged 60 years of age or older with a history of at least 10 pack-years of cigarette smoking and no history of cancer (other than non-melanotic skin cancer). Annual repeat screening will be performed until November 2003 and to date, 2,476 of them have been done. Positive results of the screening test, at baseline and annual repeat, and the subsequent work-up of these positive results were defined by a common protocol. Tabulations were made of the number of cancers diagnosed in the baseline cycle or annual repeat cycle of screening. A cancer was classified as a baseline screen-diagnosis if its diagnosis was prompted by a positive finding on the initial, low-dose CT and as a baseline interim-diagnosis if its diagnosis was prompted by symptoms occurring prior to the first annual repeat screening 12 months later. A cancer was classified as an annual repeat screen-diagnosis if its diagnosis was prompted by findings on low-dose CT performed 9-15 months after a previously negative baseline screen; it was classified as an annual repeat interim-diagnosis if its diagnosis was prompted by symptoms after a previously negative repeat screening.
Results: On baseline, low-dose CT was positive in 812 (13%) of 6,368 screenees; to date, 79 (1.2%) have had screen-diagnosed lung cancers and another 2 had interim-diagnosed ones. On annual repeat, low-dose CT was positive in 247 (10%); to date, 9 (0.4%) have had screen-diagnosed lung cancer and no interim diagnosed ones have been identified. Other potential cancers are undergoing diagnostic work-up. Both on baseline and annual repeat screening, over 80% of the screen-diagnosed cancers were of Stage I.
Conclusion: The high proportion of screen-diagnosed lung cancers on both baseline and annual repeat screening (88:2) confirms that annual repeat CT screening is sufficient to minimize symptom-prompted interim diagnoses. Annual repeat CT screening produces a high percentage of Stage I lung cancer. False-positive results were low and usually manageable without biopsy in this multi-institutional setting.