Should FAPI PET/CT be the New Standard of Care for Detecting Lymph Node Metastases in Patients with Lung Cancer?

For patients with lung cancer, fibroblast activation protein inhibitor positron emission tomography/computed tomography (FAPI PET/CT) offers superior accuracy for diagnosing lymph node (LN) metastases in contrast to fluorodeoxyglucose (FDG) PET/CT, according to a new meta-analysis.

For the meta-analysis, recently published in Academic Radiology, researchers reviewed seven studies involving a total of 409 patients with lung cancer. The reviewed studies included six comparative studies of FAPI PET/CT and FDG PET/CT, according to the meta-analysis.

The researchers found that FAPI PET/CT had overall pooled sensitivity of 88 percent, specificity of 94 percent and an area under the curve (AUC) of 97 percent for detecting LN metastases.

“These results indicate that FAPI PET/CT has a promising role for LN staging in lung cancer patients and may have the potential to be incorporated into the current diagnostic algorithm on preoperative mediastinal staging, which still calls for a large number of invasive procedures such as mediastinoscopy and endobronchial ultrasound-guided transbronchial needle aspiration due to suboptimal diagnostic accuracy of current imaging modalities,” wrote lead author Qi-chang Wan, M.D., who is affiliated with the Department of Nuclear Medicine at China-Japan Union Hospital of Jilin University in Changchun, China, and colleagues.

For the head-to-head comparative data, the study authors pointed out that FAPI PET/CT had 11 percent higher sensitivity (89 percent vs. 78 percent), 28 percent higher specificity (94 percent vs. 66 percent) and a 17 percent higher AUC (97 percent vs. 80 percent) in contrast to FDG PET/CT.

The researchers maintained that further research is necessary to determine whether FAPI PET/CT could replace FDG PET/CT as standard of care nuclear imaging for lung cancer evaluation. However, they suggested that FAPI PET/CT could be a viable alternative to invasive diagnostic procedures by providing greater clarity in patients with lung cancer who have FDG accumulation in the mediastinal LNs due to lung inflammation or granulomas.

“Due to the excellent ruling-out ability, the addition of FAPI PET/CT might greatly enhance confidence of benign findings, thus reducing these invasive procedures with associated complications in these patients,” added Wan and colleagues.

Noting that partial volume effect and physiological uptake in the mediastinal region can lead to lower visibility of lung lesions > 10 mm on FDG PET/CT, the study authors said partial volume effect is less of an obstacle with FAPI PET/CT due to the modality’s greater tracer uptake in metastatic LNs and a low mediastinal background.

(Editor’s note: For related content, see “Researchers Show Higher Breast Cancer Upstaging Rate with 18F-FAPI PET/CT,” “Study Assesses Lung CT-Based AI Models for Predicting Interstitial Lung Abnormality” and “Can Adjunctive AI Facilitate Earlier Lung Cancer Detection on Pre-Op CT Scans?”)

In regard to the meta-analysis limitations, the authors noted a relatively small number of patients that were drawn entirely from East Asia, which may limit extrapolation of the findings to broader populations. They also acknowledged significant heterogeneity between the reviewed studies.