PET/CT significance for planning radiotherapy of head and neck cancer

Abstract

The combination of positron emission tomography and computed tomography (PET/CT) offers metabolic mapping in addition to anatomic information of the primary lesion, nodal and distant metastases in patients with head and neck tumors, and may be therefore beneficial for radiotherapy planning. The aim of our study was to evaluate benefits of combined PET and CT imaging for staging and target volume delineation in this group of patients. Fifty three patients (40 men and 13 women) with confirmed advanced, inoperable or non-radically operated head and neck cancer were assessed based on the results of PET/CT as well as standard diagnostic examinations. All patients were subsequently treated with intensity modulated radiotherapy (IMRT) with simultaneous integrated boost (SIB) of 6 MV X-rays. There was an agreement between the standard examinations results and results of PET/CT in 30 cases. In 23 cases there was disagreement either in tumor size, nodal involvement or presence of distant metastases. Results of the tumor size assessment differed significantly in 5 cases. There was no agreement found in nodal involvement in 10 cases. The cancer confirmed by standard examination was not found by PET/CT in 2 cases; 3 PET/CT positive findings were not confirmed by standard examinations. In 3 patients PET-CT revealed new distant metastatic disease. Based on PET/CT assessment we changed treatment strategy and applied potentially curative dose of radiotherapy to previously undiscovered regions in 9 patients. We decided to change the treatment intent in 3 cases and only palliative treatment was applied. Based on our experience and the literature review, PET/CT may be considerable contribution to the standard diagnostic procedures in approximately one third of cases.