18F-FDG PET/CT and nestin expression as prognostic tools in pulmonary neuroendocrine tumours

The aim of this study was to investigate the fluorine-18-fluorodeoxyglucose (F-FDG) uptake on integrated PET [PET/computed tomography (CT)] images and its correlation with nestin expression in a series of neuroendocrine lung tumours. As the incidence of neuroendocrine lung tumours is rising, tools predicting diagnosis, outcome and assisting in the selection of treatment regimens are needed.

We reviewed records of patients diagnosed with large cell neuroendocrine lung carcinoma, atypical carcinoid and typical carcinoid who were operated upon in our institution. Into the study, we included those who underwent F-FDG PET/CT before the operation. Immunohistochemical staining for nestin was performed. We retrospectively reviewed patient charts and analyzed multiple variables.

Maximal standardized uptake value (SUVmax) was significantly higher in poorly differentiated than in well-differentiated tumours (P<0.001). The estimated SUVmax cut-off value, which distinguishes large cell neuroendocrine lung carcinoma from carcinoid with the highest sensitivity and specificity (88.6%; 85%), was 6.3. Positivity of the tumour on F-FDG PET/CT was associated with shorter survival of the patient (P=0.0057). Multivariate analysis showed that nodal involvement and SUVmax were predictors of adverse outcome. Nestin expression did not correlate with lymph node metastases (P=0.97), SUVmax (P=0.9), maximal size of the lesion (P=0.49) or Ki-67 (P=0.93). Nestin expression did not influence survival on multivariate analysis.

The study revealed a comparable expression of nestin in tumours with different activity of glucose metabolism measured by F-FDG uptake at PET/CT. It did not show any significant influence of nestin expression on survival. The study confirmed that F-FDG PET/CT is useful in the preoperative evaluation of patients with pulmonary neuroendocrine tumours.