Incidence of Brain Metastases on Follow-up ¹⁸F-FDG PET/CT Scans of Non–Small Cell Lung Cancer Patients: Should We Include the Brain?

Abstract

The brain is the most common site of distant metastasis from lung cancer. Thus, MRI of the brain at initial staging is routinely performed, but if this examination is negative a follow-up examination is often not performed. This study evaluates the incidence of asymptomatic brain metastases in non-small cell lung cancer patients detected on follow-up 18 F-FDG PET/CT scans. Methods: In this Institutional Review Board-approved retrospective review, all vertex to thigh 18 F-FDG PET/CT scans in patients with all subtypes of lung cancer from August 2014 to August 2016 were reviewed. A total of 1,175 18 F-FDG PET/CT examinations in 363 patients were reviewed. Exclusion criteria included brain metastases on initial staging, histologic subtype of small-cell lung cancer, and no follow-up 18 F-FDG PET/CT examinations. After our exclusion criteria were applied, a total of 809 follow-up 18 F-FDG PET/CT scans in 227 patients were included in the final analysis. The original report of each 18 F-FDG PET/CT study was reviewed for the finding of brain metastasis. The finding of a new brain metastasis prompted a brain MRI, which was reviewed to determine the accuracy of the 18 F-FDG PET/CT. Results: Five of 227 patients with 809 follow-up 18 F-FDG PET/CT scans reviewed were found to have incidental brain metastases. The mean age of the patients with incidental brain metastasis was 68 y (range, 60-77 y). The mean time from initial diagnosis to time of detection of incidental brain metastasis was 36 mo (range, 15-66 mo). When MRI was used as the gold standard, our false-positive rate was zero. Conclusion: By including the entire head during follow-up 18 F-FDG PET/CT scans of patients with non-small cell lung cancer, brain metastases can be detected earlier while still asymptomatic. But, given the additional scan time, radiation, and low incidence of new brain metastases in asymptomatic patients, the cost-to-benefit ratio should be weighed by each institution.

Brain metastases assessment by FDG-PET/CT: can it eliminate the necessity for dedicated brain imaging?

“…This is concordant with the published literature where Kitajima et al's study showed no statistical significance between these two patient groups [35]. A study proposed by Nia et al showed that all studied patients with incidental BM were symptom free [36]. It is important to diagnose BM before patients become symptomatic to avoid dangerous complications as seizures.…”

PET imaging in patients with brain metastasis—report of the RANO/PET group

“…However, the value of this procedure is highly questionable based on the limited sensitivity of FDG PET for brain tumors related to the physiologically high levels of glucose metabolism in healthy brain parenchyma. 58,59 Indeed, a prospective study has shown that, in comparison to contrastenhanced standard MRI for intracranial staging in newly diagnosed lung cancer, FDG PET has poor sensitivity (27%) for BM detection. 60 Similarly, a recent meta-analysis including more than 900 patients found that contrast-enhanced MRI has a higher cumulative sensitivity (77%) than FDG PET (21%) for the diagnosis of BM in lung cancer patients.…”

Role of miR‑520b in non‑small cell lung cancer

“…Tumor recurrence and metastasis represent key factors limiting the clinical treatment efficacy of NSCLC, the underlying mechanism of which remains to be elucidated ( 7 ). A number of previous studies have demonstrated that the recurrence and metastasis of NSCLC are closely associated with abnormal gene expression, methylation, gene mutation, drug resistance and immunosuppression ( 24 , 25 ). miRNA molecules are associated with almost all pathophysiological biological processes, which provides rationale for their use in early diagnosis and target therapy for tumors ( 26 ).…”