| Part ?:High-risk factors of parotid lymph node metastasis in nasopharyngeal carcinoma:A case-control studyObjective:Although parotid-sparing IMRT decreased the dose distribution of parotid,parotid region recurrence has been reported.Prophylactic irradiation in parotid area would be necessary in patients with high risk of parotid lymph node metastasis?PLNM?.This study was to detect the high-risk factors of PLNM in nasopharyngeal carcinoma.Methods:This was a 1:2 case-control study.All patients in this study were newly diagnosed NPC with N2-3 classification from January 2005 to December 2012.Cases were 22 sides with ipsilateral PLNM.Controls were 44 patients who were randomly selected from N2-3 disease in database.Results:20/1096?1.82%?NPC patients were found PLNM.Sum of the longest diameter for multiple lymph nodes?SLD?in level ? was larger in case group than that in control group?6.0cm vs.3.6cm,p=0.003?.Level II lymph node necrosis,level Va/b involvement,and rare neck areas involvement were more common in case group?p=0.016,p=0.034,and p<0.001,respectively?.RPN,level ?,and level IV metastases showed no significant difference between the two groups.Multivariate analysis in logistic regression showed that only SLD ?5cm in ? area?OR=4.11,p=0.030?and rare neck areas involvement?OR=3.95,p=0.045?were associated with PLNM in NPC patients.Conclusions:PLNM was an uncommon event in NPC patients.SLD ?5cm in level ?and involvement in rare-neck areas may be potentially high-risk factors for PLNM.Sparing parotid in IMRT was not recommended for NPC patients with high risks of PLNM.Part ?:Periporatid failure analysis after definitive intensity-modulated radiotherapy for Nasopharyngeal CarcinomaObjective:To discuss the potentially high-risk factors of periparotid recurrence after IMRT for nasopharyngeal carcinoma.Methods:This was a case-control study.Cases were the sides with periparotid recurrence.The controls were the sides without periparotid recurrence.We retrospectively reviewed the archives of 1096 patients with nasopharyngeal carcinoma who underwent IMRT in our center from January 2005 to December 2012.13 patients were found to suffer from periparotid recurrence?1.2%?.Comparisons between the two groups were undertaken in 12 patients with available data.Results:The median time of periparotid failure were 16?8-43?months.Eight patients of periparotid recurrence were found in superficial lobe,1 patient in deep lobe,and 3 patients in both superficial and deep lobes.Periparotid recurrence was prone to the same side of primary tumor center?p<0.001?.The cases had a higher rate of neck biopsy/dissection than the controls?p=0.025?.Compared with the controls,the cases had markedly trend of more primary residues?41.7%vs.8.3%,p=0.059?,more regional residues?58.3%vs.25.0%,p=0.090?,and more complications of primary recurrence?41.7%vs.8.3%,p=0.059?.The regional recurrence was significantly different between the cases and the controls?66.7%vs.8.3%,p=0.003?.Conclusions:Recurrence in region of parotid gland was a rare event in patients with NPC who were treated with IMRT.Locally advanced disease,residue,biopsy/dissection history of the neck,and localregional recurrence may be the potentially high-risk factors for periparotid failure.IMRT that spared parotid gland may take important responsibility.Part ?:Dosimetric analysis for radiation induced brain injury after IMRT in nasopharyngeal carcinomaObjective:The dose tolerance of brain was based on the data of 2D-RT technique.This study was aimed to investigate the dose-volume limit to protect the brain in IMRT.Methods:We reviewed 1300 NPC patients that treated with IMRT in our hospital during January 2006 to December 2013.48 patients with radiation induced brain injury?RBI?were included in this study.There were 9 patients with bilateral brain injury.Then 57 sides with ipsilateral RBI were regarded as case group,and the 39 sides without RBI were in control group.Temporal lobe,partial brain,and region of brain injury were defined as OAR to evaluate the dose distribution of brain.The dosimetric information was acquired,including Dmax,D0.5cc,D1.Occ,D2.0cc,D3.0cc,and D5.0cc.Results:After IMRT,the patients developed brain injury within an average latency of 337 months.The "temporal lobe" was not enough to cover the region of irradiated brain.The dose of "partial brain" was 0.7-2.5Gy higher than the dose in "region of brain injury",and the dose of "partial brain" was closely correlated with that of "region of brain injury".When the "partial brain" was regarded as the OAR,the Dmax,DO.5cc,D1.0cc,D2.0cc,D3.0cc,and D5.0cc in case group were obviously higher than that in control group.The ROC curve analysis showed that Dmax 75Gy,D0.5cc 71 Gy,D1.0cc 68Gy,D2.0cc 65Gy,D3.0cc 63Gy,and D5.0cc 59Gy would be the optimized cut-off points to discriminate the risk of RBI?all AUC>0.85,p<0.001?.Conclusion:In the 3D radiation technique era,there exists an increase in tolerance dose when a small volume of brain was irradiated.When the "partial brain" was regarded as the OAR,we suggest the dose limits of brain are Dmax 75Gy,D0.5cc 71Gy,D1.0cc 68Gy,D2.0cc 65Gy,D3.0cc 63Gy,and D5.0cc 59Gy.Part ?:The development of radiation induced brain injury and effect analysisObjective:Radiation induced brain injury?RBI?was a severe complication of radiation.There were challenges in the treatment of RBI.This study was designed to investigate the development of RBI and to find the factors that affect the results.Methods:We reviewed 1300 NPC patients that treated with IMRT in our hospital during January 2006 to December 2013.There were 58 patients with RBI,and 12 patients were removed because of no derailed follow-up data.We collected follow-up data 3-24 months after RBI.RECIST guideline was used to evaluate the efficacy of RBI.Results:We divided the follow-up time to 3 periods,3-6 months,10-12 months,18-24 months.In 3-6 months,most patients were evaluated as PD or SD,and 21.9%patients were evaluated as PD.However,in 10-12 months,most patients were evaluated as response or SD,and 36.1%patients responded.Then,in 18-24 months,45.2%patients responded and only 12.9%patients were PD.Patients were divided into responded group and non-responded group.The frequency distribution of gender,age<10,histology,smoking history,T classification,high-intensity treatment,and irradiated dose showed no significant difference between the two group.However,patients treated with ganglioside can increase the response rate.The response rate of ganglioside group was 68.8%in 10-12 months,?p<0.001?,and was 81.8%in 18-24 months?p =0.008?.Multivariate analysis showed that treatment with ganglioside was a favorable factor for the response of RBI in both 10-12 months evaluation?OR =19.8,p =0.001?and 18-24 months evaluation?OR =13.5,p =0.005?.Conclusion:Radiation induced brain injury after IMRT in NPC patient frequently has two stage,active stage and stable stage.It is rarely irreversible or lethal disease in RBI patients.Treatment with ganglioside in active stage may be effective in patients with RBI... |
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