PET-CT Used for Lung Cancer Diagnosis May Be Less Effective in Areas Where Infectious Lung Disease Is More Common

An analysis of data gleaned from 70 studies revealed that use of the diagnostic imaging modality fluorodeoxyglucose F18 (FDG)-positron emission tomography (PET) combined with computed tomography (CT) may not effectively differentiate benign disease from lung cancer in patients with endemic (high prevalence) infectious lung disease compared with nonendemic regions, according to recent research.

The findings were published September 24, 2014, in the Journal of the American Medical Association (JAMA). Depending on the risk for cancer, diagnostic guidelines suggest or advise to use FDG combined with PET as a noninvasive imaging modality to evaluate the risk of cancer or benign disease.

Stephen A. Deppen, PhD, from the Tennessee Valley Healthcare System and Vanderbilt University Medical Center (Nashville, TN, USA) and colleagues conducted a meta-analysis to assess the accuracy of FDG-PET to identify lung lesions in regions with locally endemic infectious lung diseases. The researchers identified 70 studies that met criteria for inclusion in the analysis. The studies reported on a total of 8,511 nodules; 5,105 (60%) were malignant.

Pooled sensitivity of FDG-PET for detecting lung cancer was 89% and pooled specificity was 75%. There was a 16% lower average adjusted specificity in regions with endemic infectious lung disease (61%) compared with nonendemic regions (77%). Lower specificity was seen when the analysis was limited to rigorously conducted and well-controlled studies.

“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 wrote in their article.

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