ABSTRACT
Objective@#To assess the interobserver variations in delineating the planning target volume (PTV) and organs at risk (OAR) using different contouring methods during intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC), aiming to provide references for the quality control of multi-center clinical trials.@*Methods@#The PTV and OAR of CT image of 1 NPC patient manually delineated by 10 physicians from 8 different radiation centers were defined as the " manual contour group" , and the OAR auto-contoured using the ABAS software and modified by the physicians were defined as the " auto+ manual contour group" . The maximum/minimum ratio (MMR) of the PTV and OAR volumes, and the coefficient of variation (CV) for different delineated contours were comparatively evaluated.@*Results@#Large variation was observed in the PTV and OAR volumes in the manual contour group. The MMR and CV of the PTV were 1.72-3.41 and 0.16-0.39, with the most significant variation in the PTVnd (MMR=3.41 and CV=0.39 for the PTVnd-L). The MMR and CV of the manually contoured OAR were 1.30-7.89 and 0.07-0.67. The MMR of the temporal lobe, spinal cord, temporomandibular joint, optic nerve and pituitary gland exceeded 2.0. Compared with the manual contour group, the average contouring time in the auto+ manual group was shortened by 68% and the interobserver variation of the OAR volume was reduced with an MMR of 1.04-2.44 and CV of 0.01-0.37.@*Conclusions@#Large variation may occur in the PTV and OAR contours during IMRT plans for NPC delineated by different clinicians from multiple medical centers. Auto-contouring+ manually modification can reduce the interobserver variation of OAR delineation, whereas the variation in the delineation of small organs remains above 1.5 times. The consistency of the PTV and OAR delineation and the possible impact upon clinical outcomes should be reviewed and evaluated in multi-center clinical trials.
ABSTRACT
Objective To assess the interobserver variations in delineating the planning target volume (PTV) and organs at risk (OAR) using different contouring methods during intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC),aiming to provide references for the quality control of multi-center clinical trials.Methods The PTV and OAR of CT image of 1 NPC patient manually delineated by 10 physicians from 8 different radiation centers were defined as the "manual contour group",and the OAR auto-contoured using the ABAS software and modified by the physicians were defined as the "auto+manual contour group".The maximum/minimum ratio (MMR) of the PTV and OAR volumes,and the coefficient of variation (CV) for different delineated contours were comparatively evaluated.Results Large variation was observed in the PTV and OAR volumes in the manual contour group.The MMR and CV of the PTV were 1.72-3.41 and 0.16-0.39,with the most significant variation in the PTVnd (MMR=3.41 and CV =0.39 for the PTVnd-L).The MMR and CV of the manually contoured OAR were 1.30-7.89 and 0.07-0.67.The MMR of the temporal lobe,spinal cord,temporomandibular joint,optic nerve and pituitary gland exceeded 2.0.Compared with the manual contour group,the average contouring time in the auto+ manual group was shortened by 68％ and the interobserver variation of the OAR volume was reduced with an MMR of 1.04-2.44 and CV of 0.01-0.37.Conclusions Large variation may occur in the PTV and OAR contours during IMRT plans for NPC delineated by different clinicians from multiple medical centers.Auto-contouring+ manually modification can reduce the interobserver variation of OAR delineation,whereas the variation in the delineation of small organs remains above 1.5 times.The consistency of the PTV and OAR delineation and the possible impact upon clinical outcomes should be reviewed and evaluated in multi-center clinical trials.
ABSTRACT
Objective To explore the feasibility of employing a risk category system in evaluating the treatment outcome of locoregionally advanced nasopharyngeal carcinoma (NPC) treated by intensitymodulated radiation therapy (IMRT) alone,and offering evidence for relevant perspective studies.Methods Totally 185 locoregionally advanced NPC patients were divided into high-risk and low-risk groups for evaluation and comparison.The patients who met at least one of the following criteria were defined as high-risk group and others as low-risk group:GTVnx ＞ 30 cm3;Clinical stage T4N2M0;multiple neck node metastases with 1 node size ＞4 cm,and N3 with any T stage.Results With a median follow up of 110.9 months (6.7-152.4 months),the 5-year overall survival,locoregional relapse-free survival,distant metastasis-free survival for the high-risk group vs.the low-risk group were 61.0％ vs.90.5％ (x2 =30.298,P＜0.05),78.3％ vs.91.5％ (x2 =6.352,P＜0.05)and 71.6％ vs.92.0％ (x2 =16.346,P ＜0.05).Conclusions As a simple and practicable method,the risk category system is helpful for discriminating locoregionally advanced nasopharyngeal carcinoma with different risk-group of treatment failure and in further perspective clinical research.
ABSTRACT
ObjectiveTo explore the prognostic value of pretreated maximum standardized uptake value (SUVmax) using 18-fluorodeoxyglucose positron emission tomography with computed tomography (18FDG PET/CT) in locally-advanced nasopharyngeal carcinoma (NPC) treated by intensity-modulated radiotherapy (IMRT).MethodsOne hundred and forty previously untreated stage Ⅲ - Ⅳb ( UICC/AJCC 6th) patients with biopsy-proven nasopharyngeal carcinoma were examined.All of the enrolled patients accepted whole body/head-neck 18FDG PET/CT before radical IMRT. 18FDG uptakes were recorded as SUVmax of primary tumor (SUVmax-P) and SUVmax of cervical lymph nodes (SUVmax-N).The relationships between SUVmax and long-term clinical outcomes were analyzed.ResultsThe median SUVmax-P was 10.4,and the median SUVmax-N was 6.2.The SUVmax-P was weakly correlated with T-stage ( R =0.279,P =0.001 ).The SUVmax-N was weakly correlated with N stage ( R =0.334,P =0.000 ).There were no difference of the median SUVmax-P (9.2 vs.10.4,U =560.50,P =0.805 ) and the median SUVmax-N (4.0vs.5.0,U =576.00,P =0.908) between patients with and without local recurrence.The median SUVmax-P of patients with distant metastasis was significantly higher than those without metastasis (11.9 vs.9.8,U =987.50,P =0.014).The SUV of 10.2 was taken as a cut-off for high and low uptake tumors.For patients with SUVmax-P ＞ 10.2,the 5-year distant metastasis-free survival (DMFS) and 5-year overall survival (OS)were significantly higher than those with SUVmax-P ≤ 10.2 (69.1％ vs.95.5％,x2 =15.88,P =0.000;68.4％ vs.94.0％,x2 =15.56,P =0.000,respectively).Multivariate analysis showed that SUVmax-P was the only independent risk factor of 5-year DMFS and OS ( HR =7.87,P =0.001 and HR =5.14,P =0.003). Conclusion SUVmax-P is a useful biomarker predicting long-term clinical outcomes in newly diagnosed locally-advanced NPC patients.