A simple, inexpensive computer tool that measures volume changes in the size of suspicious nodules in the lungs picked up by a CT scanner can rule out non-cancerous ones with almost perfect accuracy and enable doctors to diagnose true cancers with fewer, less expensive and less invasive tests.
The new diagnostic guidelines are described in a paper published on December 3, 2009 in the New England Journal of Medicine on the progress of large European lung cancer CT screening trial (NELSON) launched in the Netherlands and Belgium in 2004. Advances in imaging technology have enabled scanners to detect suspicious nodules in the lung smaller than a grain of rice, but how to determine which ones are cancerous without further expensive or invasive and potentially dangerous testing is the question. NELSON collaborators addressed the issue by using volume measurement and volume doubling time as the criteria for further action, a concept first proposed by CT diagnostic pioneers with the International Early Lung Cancer Action Program. The refined protocol can rule out non-cancer nodules with 99.9% accuracy and at the same time reduce the number of tests required to confirm cancer in a malignant nodule. In the NELSON trial, only 1% of positive cancers required a biopsy for confirmation. The NELSON trial will continue to examine the mortality impact of CT screening by comparing the number of lung cancer deaths that occur among the 7557 people getting scans with a similar number of people who do not. In the United States, the National Lung Screening Trial is also looking at mortality differences between those screened with a chest x-ray and those screened with a CT scan. Both trials are expected to be completed within the next three to five years.