In a recent study entitled, “Accuracy of FDG-PET to Diagnose Lung Cancer in Areas With Infectious Lung Disease” published in The Journal of the American Medical Association, a group of researchers from Vanderbilt University Medical Center in Nashville, led by Eric L. Grogan, MD, MPH, concluded that noninvasive positron emission tomography (PET) combined with fludeoxyglucose F 18 (FDG), a test used to diagnose lung cancer, may not identify malignant lesions in populations with endemic infectious lung diseases.
In FDG-PET analysis, cancerous tumors have a different morphology than healthy parts of the lungs that do not have cancer. However, this difference can sometimes be difficult to distinguish between lung cancer and certain lung infections, such as tuberculosis and fungal infections.
The team searched MEDLINE, EMBASE, and the Web of Science databases from October 2000 through April 2014, identifying a total of 257 articles that reported enough information to calculate sensitivity and specificity of FDG-PET to diagnose lung cancer. Overall, 70 studies were included in the analysis, with a total of 8511 nodules, 60% of which were malignant.
The authors observed that geographic regions where tuberculosis is common include China, Japan and South Africa, whereas areas where fungal lung infections usually occur include the Mississippi, Missouri, and Ohio river valley regions, as well as the U.S. Southwest, and Ontario, Canada.
Their analysis results’ demonstrated that FDG-PET held an 89% ability of accurately identifying people with lung cancer, and a 77% capacity to identify patients without lung cancer.
Nonetheless, upon exclusive examination of geographic areas with endemic infectious lung diseases, there was a 16% lower average specificity of FDG-PET scans, when compared to non-endemic areas, which means that lung cancer in those areas may have been incorrectly identified and mistaken for other lung diseases.
The results also showed that the accuracy of FDG-PET for diagnosing lung nodules was extremely heterogeneous.
Altogether, the authors defend that the data obtained from this study “does not support the use of FDG-PET to diagnose lung cancer in endemic regions unless an institution achieves test performance accuracy similar to that found in non endemic regions.”