Molecular whole-body cancer staging using positron emission tomography: consequences for therapeutic management and metabolic radiation treatment planning.

A prospective analysis was performed in 124 non-small cell lung cancer patients to determine the role of F-18 fluorodeoxyglucose (FDG)-positron emission tomography (PET) for molecular (metabolic) staging (n=63), therapy monitoring after induction-chemotherapy (n=34), and conformal radiation treatment planning (n=27). Staging by FDG-PET was significantly more accurate than CT (p<0.001) and changed therapeutic management in 52% of all patients. After induction-chemotherapy, patients with complete metabolic remission histologically did not show vital tumor cells in contrast to patients with metabolic partial remission or progressive disease. Metabolic radiation treatment planning by PET led to smaller planning target volumes (PTVs) for radiation therapy (between 3% and 21% in 25/27 patients), resulting in a reduction of dose exposure to healthy tissue. In two patients, PET-PTV was larger than CT-based PTV, since PET detected lymph node metastases smaller than 1 cm. FDG-PET provides clinically important information; changes therapeutic management, can predict noninvasively effectiveness of chemotherapy, and may lead to better tumor control with less radiation-induced toxicity.