The aim of our study was to investigate changes in clinical staging N (lymph node)
and M (distant metastasis) in patients who receive PET/CT-based 3D radiotherapy within
complex oncological treatment, and compare to conventional cross-sectional imaging
staging technique. We also investigated the presence of PET/CT-detected second tumors
and the effect of PET/CT on therapeutic decisions.From the 1st of January 2015 to
the 30th of November 2016, 192 patients (n = 192) were treated with PET/CT-based radiation
(109 head, 44 lung, 28 rectum and 11 cervical localization) in the Oncoradiology Institute
of the Health Center of the University of Kaposvár. All patients received conventional
cross-sectional and PET/CT imaging in accordance with the valid investigation protocol.
The average time interval between the two cross-sectional investigations was 5.2 weeks.
Clinical N and M staging was performed on the basis of the classification of the American
Joint Committee on Cancer (AJCC) and the Union of International Cancer Control (UICC).By
analyzing the clinical stages N and M separately, based on the results of the PET/CT
studies, the N stage was changed in 77 cases and the M stage changed in 31 cases.
Overall, the PET/CT study resulted in higher clinical stages in 68 (35.4%) patients
and lower clinical stages in 14 (7.3%) patients. The treatment plan was changed in
9% of the patients (n = 18) (definitive versus palliative treatment) and the extension
of radiotherapy treatment target volume (PTV) was indicated in 20% of the patients
(n = 39) due to the change in clinical lymph node status. PET/CT also detected secondary
tumors in 15 (8%) patients.Based on our results, the addition of PET/CT to conventional
cross-sectional staging imaging permits a more accurate clinical classification of
N and M stages and significantly influences therapeutic decisions. PET/CT imaging
also provides a great help in detecting occult second tumors. The results of our Institute
harmonize with the international data available in the literature. Orv Hetil. 2018;