APPLICATION OF FDG POSITRON-EMISSION-TOMOGRAPHY IN RADIATION TREATMENT PLANNING OF HEAD AND NECK TUMORS

Purpose: An individualized radiation treatment planning in patients wi th head and neck tumors requires an exact definition of tumorspread. D espite of high reliability of methods like computed tomography, sonogr aphy or magnetic resonance imaging used in daily routine, the correct diagnosis of lymphonodal tumor infiltration is often not possible. In a prospective trial, we examined whether an additional FDG-PET gives a relevant gain of information fur radiation treatment planning. Patien ts and Methods: We studied data of 34 patients with histologically con firmed squamous cell carcinoma of the head and neck who received a FDG -PET prior to treatment planning additionally to conventional staging procedures. The extent of changes of treatment strategy or target volu me due to additional FDG-PET findings were analyzed. Results: In 9/22 of patients with primary tumors and in 7/12 of patients with recurrent disease. FDG-PET detected additional tumor manifestations. In all cas ts, changes of treatment strategy or target volume were necessary. Reg arding patients with primary tumors, the percentage of treatment modif ications was highest in patients with large tumors (T3 and T4) and pat ients with advanced lymph node involvement (N2 and N3). Conclusions: E specially in patients with recurrent disease and patients with advance d tumor stages, FDG-PET is able to give clinically relevant informatio n compared to conventional staging procedures. Therefore, in these gro up of patients a FDG-PET study prior to radiotherapy planning should b e considered.