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Background: This study examined genomic factors associated with a reduction in fluoro-2-deoxy- D-glucose (FDG) uptake during positron emission tomography-computed tomography (PET-CT) for definitive chemoradiotherapy (CRT) in patients with pharyngeal cancer. Methods: The pretreatment and interim PET-CT images of 25 patients with advanced pharyngeal cancers receiving definitive CRT were prospectively evaluated. The maximum standardized uptake value (SUV) of the interim PET-CT and the reduction ratio of the SUV (SRR) between the two images were measured. Genomic data from pretreatment incisional biopsy specimens ( SLC2A1, CAIX, VEGF, HIF1A, BCL2, Claudin-4, YAP1, MET, MKI67, and EGFR) were analyzed using tissue microarrays. Differences in FDG uptake and SRRs between tumors with low and high gene expression were examined using the Mann-Whitney test. Cox regression analysis was performed to examine the effects of variables on local control. Results: The SRR of the primary tumors (SRR-P) was 0.59 ± 0.31, whereas the SRR of metastatic lymph nodes (SRR-N) was 0.54 ± 0.32. Overexpression of HIF1A was associated with a high iSUV of the primary tumor ( P < 0.001) and neck lymph node ( P = 0.04) and a low SRR-P ( P = 0.02). Multivariate analysis revealed that patients who had tumors with low SRR-P or high HIF1A expression levels showed inferior local control. Conclusion: In patients with pharyngeal cancer requiring CRT, HIF1A overexpression was positively associated with high interim SUV or a slow reduction in FDG uptake. Prospective trials are needed to determine whether the local control rate can be stratified using the HIF1A level as a biomarker and SRR-P. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the study was to investigate the predictive role of pretreatment metabolic volume (MTV) in pharyngeal cancer (PC) patients treated with definitive (chemo) radiotherapy. Methods: This retrospective analysis enrolled 64 patients with PC treated with (chemo) radiotherapy. All patients received pretreatment fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT. Four PET segmentation methods were used, namely applying an isocontour at a standardized uptake value (SUV) of either 2.5 or 3.0 (MTV2.5 and MTV3.0) or using fixed thresholds of either 40 or 50 % (MTV40 %, MTV50 %) of the maximum intratumoural FDG activity. Disease-free survival (DFS) and primary relapse-free survival (PRFS) were examined according to cutoffs of the median values for each MTV and the gross tumour volume (GTVp). Independent prognosticators were identified by Cox regression analysis. Results: With a median follow-up of 24 months, 19 patients died, and 26 patients experienced tumour relapse at primary sites. Multivariate analysis of the DFS showed that MTV2.5 > 13.6 ml was the only predictor of relapse [ p = 0.011, hazard ratio = 2.69, 95 % confidence interval (CI) 1.25-5.76]. The independent predictor for PRFS was MTV2.5 > 13.6 ml ( p = 0.003, hazard ratio = 3.76, 95 % CI 1.57-8.92), whereas GTVp > 15.5 ml had a marginal impact on PRFS ( p = 0.06, hazard ratio = 3.54, 95 % CI 0.97-11.85). Patients having tumours with MTV2.5 > 13.6 ml had a significantly inferior 2-year PRFS compared with patients who had lower MTV2.5 tumours (39 vs 72 %, respectively, p = 0.001). Conclusion: For PC patients treated with definitive (chemo)radiotherapy, pretreatment MTV2.5 volume achieved the best predictive value for primary recurrence, and the same value was also a prognosticator for DFS. [ABSTRACT FROM AUTHOR]