Predictive value of PET/CT based metabolic information in the modern 3D based radiotherapy treatment of head and neck can-cer patients - single institute study.

OBJECTIVE: The aim of the study was to evaluate the predictive value of pretreatment positron emission tomography (PET) standardized uptake value (SUVmax), standardized uptake value corrected for lean body mass (SULpeak) value, metabolic tumour volume (MTV) and total lesion glycolysis (TLG) parameters of the primary tumour assessed with PET/computed tomography (CT) in the clinical out-come in patients diagnosed with histopathologically confirmed head and neck squamous cell carcinoma. MATERIALS AND METHODS: Retrospective evaluation was performed using PET/CT image datasets of 52 histologically proven head and neck cancer patients in 4 weeks' prior receiving definitive chemo-radiotherapy (CRT). Positron emission tomography /CT was performed before the CRT and 12 weeks after it for response evaluation. Image data was used for target volume delineation and for specify SUVmax, SULpeak, MTV and TLG parameters of the primary tumour. According to the results of the therapeutic response evaluation two patient subgroups were created in relation to the presence or absence of viable tumour. Metabolic data from pre-treatment PET/CT and therapeutic response were correlated using Kruskal-Wallis test. RESULTS: After completion of the CRT in 24/52 (46%) cases viable residual tumour was detected on restaging PET/CT, while in 28/52 (54%) patients showed complete remission. For the therapeutic success prediction assessment, we could not find any significant correlation with pre-treatment SUVmax and SULpeak values (P>0.44, P>0.33). Total lesion glycolysis provided nearly significant difference (P=0.052) and MTV had shown significant difference (P=0.001) between the two patient subgroups statistically. CONCLUSION: Simple metabolic data (SUVmax and SULpeak) from pretreatment fluorine-18-fluorodeoxyglucose (18F-FDG) PET/CT were unable to predict therapeutic response, while volumetric information containing MTV and TLG parameters proved to be more useful, thus their inclusion to risk stratification may also have additional value.

[The predictive role of PET/CT imaging in clinical N and M staging and treatment decision process. Institutional experiences in Hungary]. / A PET/CT szerepe a sugárkezelésre kerülo betegek N és M klinikai stagingjében, a terápia meghatározásában. Intézeti tapasztalatok.

INTRODUCTION AND AIM: 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. METHOD: 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). RESULTS: 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. CONCLUSION: 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; 159(39): 1593-1601.