Projected Outcomes Using Different Nodule Sizes to Define a Positive CT Lung Cancer Screening Examination

Data from the National Lung Screening Trial (NLST) were examined by exploring different size thresholds for classifying CT screening scans as positive.  In the NLST, nearly two-thirds of nodules were 7mm in diameter or less.  Using a threshold of 5mm, the percentage of missed/delayed diagnosis and the likelihood of avoiding false positive findings were 1% and 16%.  Using a threshold of 8mm increased those rates to 11% and 66%.  Increasing size thresholds reduced follow-up CTs and invasive procedures.  Interestingly, differences in thresholds did not affect survival or mortality.