Geographic variations in chest-CT scan lung cancer diagnosis from environmental exposures

Abstract

Chest CT scans allow radiologists to obtain a more detailed and thorough image compared to chest x-rays; therefore, chest CT scans frequently detect small suspicious non-urgent indeterminate pulmonary nodules. The goals of managing suspicious non-urgent indeterminate pulmonary nodules are early cancer detection, avoidance of unnecessary procedures for benign nodules, and efficient economic use of resources in distinguishing between benign and malignant nodules. The interpretation of these small suspicious non-urgent indeterminate nodules can vary. One reason that there may be variability in the interpretation of chest CT scan results is prior exposure to fungal lung infection causing spores such as histoplasmosis and coccidioidomycosis. This dissertation first focuses on quantifying levels of exposure of histoplasmosis and coccidioidomycosis across the US more precisely. Second, we examine how histoplasmosis endemicity and exposure is associated with the detection and follow-up of suspicious non-urgent indeterminate pulmonary nodules on diagnostic chest-CT scans. Lastly, we quantify the costs of the imaging and follow-up of suspicious non- urgent indeterminate pulmonary nodules. The financial and health outcomes of this study may influence imaging procedure and policy prioritization for healthcare providers and health system decision makers.