Is FDG-PET scan in patients with early stage Hodgkin lymphoma of any value in the implementation of the involved-node radiotherapy concept and dose painting?
OBJECTIVE
To evaluate the input of FDG-PET data in the implementation of the involved-node radiotherapy concept and dose painting.


METHODS
Patients with early-stage Hodgkin lymphoma treated with combined modality treatments. First, patients underwent a PET/CT before chemotherapy in the treatment position using a head and shoulder immobilization mask. Second, all patients had a CT simulation for treatment planning. The CT simulation was coregistered with the prechemotherapy CT and FDG-PET scan. All prechemotherapy volumes were superimposed on the CT simulation. The initially involved lymph node areas to be irradiated were delineated on the CT simulation scan. Chemotherapy-induced shrinkage rates of the tumor masses visible on CT scan and on FDG-PET were determined and compared.


RESULTS
Before chemotherapy, FDG-PET-avid areas represented 25% of the total volume on CT. After chemotherapy, the influence of initial FDG-PET data on the delineation of involved-node radiotherapy fields was significant and was due to the fact that in 36% of the patients, FDG-PET helped pinpoint lymph nodes that were undetected on CT. After chemotherapy, the rates of tumor volume shrinkage on CT and FDG-PET were similar. This finding suggests similar chemosensitivity for FDG-PET-avid and non-avid areas. There was no correlation between initial FDG-PET-avid volumes and the clinical outcome.


CONCLUSIONS
Prechemotherapy FDG-PET data are essential for correctly implementing the involved-node radiotherapy concept but seem to be of minimal value for applying the concept of dose painting.
Girinsky
Theodore
T
Department of Radiation Oncology, Institut Gustave Roussy, Villejuif, France. girinsky@igr.fr
Ghalibafian
Mithra
M
Bonniaud
Guillaume
G
Bayla
Aziz
A
Magne
Nicolas
N
Ferreira
Ivaldo
I
Lumbroso
Jean
J
D005260:Female; D019788:Fluorodeoxyglucose F18; D006689:Hodgkin Disease / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D049268:Positron-Emission Tomography; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden
D019788:Fluorodeoxyglucose F18