Lung Cancer Tests Less Effective where Infectious Lung Disease is Common
Screening for health diseases is an important preventive measure. However, in some cases, tests can lead to false positives, resulting in more testing that might not be needed. In a new study, researchers reported that lung cancer diagnostic tests, in particular, become less effective when conducted in areas where infectious lung disease is a common health problem.
For this study, the researchers analyzed 70 studies that examined the use of different diagnostic screening tools, which included the imaging procedure of fludeoxyglucose F18 (FDG)-positron emission tomography (PET) and computed tomography (CT). The diagnostic procedures were used to look for lung cancer. FDG-PET is the typically recommended noninvasive test to assess risk of cancer or benign disease.
The researchers headed by Stephen A. Deppen, Ph.D., of the Tennessee Valley Healthcare System and Vanderbilt University Medical Center, Nashville, examined the accuracy rate of using FDG-PET and CT to diagnose lung lesions in areas where there was either a high or low prevalence rate of infectious lung disease. There were a total of 8,511 nodules with 5,104, or 60 percent, of the being malignant.
The team discovered that the use of FDG-PET in combination with CT was less effective in differentiating between lung cancer and benign disease in areas with endemic infectious lung disease in comparison to nonendemic (low prevalence) regions. The researchers calculated that the pooled sensitivity and pooled specificity of FDG-PET in diagnosing lung caner were 89 and 75 percent respectively. When the team compared endemic and nonendemic regions, they found that the specificity rates were 61 and 77 percent respectively.
"FDG-PET for the diagnosis of lung cancer in patients who reside in a region with significant endemic infectious lung disease should be recognized as having lower specificity than previously reported. Knowledge of this reduction in specificity should limit the use of FDG-PET to diagnose lung cancer unless substantial institutional expertise in FDG-PET interpretation has been proven. Should low-dose CT screening for lung cancer become the diagnostic standard, knowledge of FDG-PET/CT performance is even more critical because the vast majority of indeterminate lung nodules detected through screening are benign," the authors concluded according to the press release.
The study was published in JAMA.