Lung uptake of fluorine-18 fluoroethyl-choline PET-CT in patients with prostate cancer

BACKGROUND: Metastatic spreading to the lungs is a negative prognostic factor in patients with prostate cancer (PC). Aim of our study was to assess the prevalence of lung PC metastases in patients with fluorine-18 fluoroethyl-choline (F-18-FECh) PET-CT positive lung lesions and the role of Gleason Score (GS) and common biochemical markers in predicting metastatic spreading to the lungs. METHODS: We retrospectively evaluated the scans of 1283 patients ongoing (F-18-FECh) PET-CT for PC between May 2010 and July 2014. Patients with lung lesion with F-18-FECh uptake were included. Data concerning GS at diagnosis, "trigger" prostate-specific antigen (PSAtr), PSA doubling time (PSAdt), PSA velocity (PSAvel) and ongoing androgen deprivation therapy were collected. PET-CT findings were confirmed by histology or followup (FU) and classified as follows: inflammation, primary lung cancer or metastases from tumour other than PC, and lung metastases from PC. RESULTS: Twenty-two patients with F-18-FECh positive lung lesion and available histology or FU were identified. PSAdt was significantly (p=0.029) shorter in patients with lung metastases from PC (median PSAdt 1.7 months, interquartile range [IQR] 1.5-4.1 months) than in patients without lung PC relapse (median PSAdt 6.7 months, IQR 3.9-7.8); PSAvel was significantly (p=0.019) higher in patients with lung metastases from PC (median PSAvel 3.2 ng/ml/month, IQR 0.65-6.65 ng/ml/month) than in patients without lung PCrelapse (median PSAvel 0.3 ng/ml/month, IQR 0.2-0.5 ng/ml/month). Patients with lung metastases from PC had significantly (p=0.006) higher GS at diagnosis (median GS 8) than the other ones (median GS 7). CONCLUSIONS: Our analysis shows that the prevalence of F-18-FECh positive lung metastases in patients with PC, especially with higher GS at diagnosis, is higher in presence of a steady increase in PSA values, confirmed by higher PSAvel and shorter PSAdt.