Indeterminate pulmonary nodules on CT images in breast cancer patient: the additional value of 18F-FDG PET/CT

Abstract

Aim: To assess the potential role of 18F-Fluorodeoxiglucose (FDG) Positron Emission Tomography (PET)/Computed Tomography (CT) in characterizing indeterminate lung nodules detected at CT scan in patients previously treated for a breast cancer (BC).

Materials and methods: Twenty-nine consecutive BC patients (28 females, mean age 65 ± 12 years) with evidence of indeterminate lung nodules at contrast-enhanced CT (CECT) scan (lesions with axial diameter ≥8 mm) were retrospectively analysed: all patients underwent 18F-FDG PET/CT within a mean 2 ± 1 months from CECT imaging. PET/CT was considered positive in the presence of abnormal FDG uptake in the pulmonary nodules and/or in other organs. The nature of lung nodules was defined at histopathology and/or imaging follow-up.

Results: Fourteen (48%) patients showed negative and 15 (52%) positive PET/CT scan in the lungs: of these 15 patients, 7 (47%) had pathologic FDG-uptake in lungs only, whereas 8 (53%) showed abnormal FDG-uptake also in sites different from lungs. At histology and/or imaging follow-up, five (17%) patients were considered positive for BC lung metastases while in seven (24%) a second cancer was diagnosed. In this subset of patients, the sensitivity and specificity for FDG PET/CT in revealing lung lesions were 17% and 100%, respectively, for nodules <8 mm in diameter, and 77% and 85%, respectively, for nodules with diameter ≥8 mm. The therapeutic planning was changed to surgery in seven patients, chemotherapy in one patient and continued hormonal therapy in five. The inclusion of PET/CT in the diagnostic algorithm of the evaluated patients helped avoid unnecessary over-treatment in 12 of 29 patients.

Conclusion: FDG PET/CT appears useful in characterizing indeterminate lung nodules found at CECT scan in BC patients, with a sensitivity that is proportional to nodule size. In addition, PET/CT helped in avoiding over-treatment in a significant proportion of patients.