Prognostic value of pretherapeutic FDG PET/CT in non-small cell lung cancer with pulmonary lymphangitic carcinomatosis

Pulmonary lymphangitic carcinomatosis (PLC) is associated with a poor prognosis in patients with non-small cell lung cancer (NSCLC). We sought to determine prognostic value of pretherapeutic fluorine-18-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in NSCLC with radiologically diagnosed PLC. We retrospectively reviewed 50 NSCLC patients with radiologically diagnosed PLC. Among eight clinical variables and five imaging parameters, metabolic PLC burden, which represents the overall tumor burden of PLC, and cPLC, which represents the location and extent of PLC in a three-grade system, were used. In multivariate analyses for progression-free survival, metabolic PLC burden (P = 0.0181), cPLC (P = 0.0401), and clinical stage (P = 0.0284) were identified as independent prognostic factors. High metabolic PLC burden had a worse prognosis, and the prognosis of cPLC3 was significantly worse than that of cPLC1 or cPLC2. In univariate analyses for overall survival, only age (P = 0.0073) was identified a prognostic factor. In conclusion, FDG PET/CT parameters were identified as independent prognostic factors in NSCLC with radiologically diagnosed PLC. Furthermore, a combination of anatomical and metabolic information about PLC obtained using FDG PET/CT provides insight into the overall tumor burden of PLC and is useful in predicting prognosis.