The Dosimetry Analysis For Esophageal Cancer Local Failure After The Three Dimensional Conformal Intensity Radiotherapy

Objective:The aim of this study is that explore the characteristic of dosedistribution with the local region failure of esophageal carcinoma after definiteradiotherapy, supply the dose and volumes parameters for evalution the plan oftreatment and find the susceptivity factors of failure, then improve the localregion control and long term survival.Methods:From Jan.2006to Dec.2011,244patients were included in thisstudy.142cases with involved-field irradiation(IFI) and102cases with electivenodal prophylactic irradiation(ENI). Whole group recieved prescription dose54～66Gy, median dose62Gy, which IFI group’s prescription dose54～66Gy,ENI group front course dose46～52Gy, then esophageal local lesion plus6～16Gy. Determining the region failure cases after radiotherapy by follow-upresult、imaging results by reexamination、confirmed by pathology, assess theirinitial treatment plan and compared with the no failure patients’ treament plan,observe the dose and volume parameters between them for a comparation andanalysis. Furthermore, selecting the patients with complete datas and confirmedesophageal lesion local failure、no esophageal lesion local failure patients at thesame time control, contrast and analyze the two groups’ dose and volumeparameters of their treating plan. Dose parameters to observe the D98%、D95%、D50%、D2%of GTV、CTV、PTV, elective nodal prophylacticirradiation CTV1and PTV1’s D98%、D95%、D50%、D2%of ENI group;volume parameters to observe the GTV、CTV、PTV accept60Gy、55Gy、50Gy dose percentage(V60、V55、V50), ENI group to observe the V50、V45ofthe CTV1and PTV1. Kaplan-Meier method was used for survival analysis andtwo independent samples t test was used for measurement datas, P＜0.05defined to be statistically significant. Results:1Survival analysisThe1,3,5-year local control rates were65.5%、43.3%、39.0%;1,3,5-yearsurvival rates of whole group were68.4%、32.3%、21.6%;1,3,5-year withoutdistant metastases survival rates were80.8%、67.0%、55.8%.2Treatment failure modes244cases of whole group, follow-up to Nov.2013,165cases failure aftertreatment, the failure rate was67.6%;127cases region failure, region failurerate was52.1%;68cases appear distant metastases after treatment, distantmetastases rate was27.9%; The region failure cases include117(92.1%)esophageal primary tumor uncontrol or relapse cases and23(18.1%) regionallymph node metastasis cases. The distant metastases cases include26(38.2%)outside regional lymph node metastasis cases and51(75%)blood organsmetastasis cases.3Dosimetry analysis of local region failure cases and no failure casesThe244cases include local region failure127cases and117cases withno local region failure, compare the two groups’ dose (D98%、D95%、D50%、D2%)and volume(V60、V55、V50) parameters of GTV、CTV、PTV, didn’tshow any statistically significant difference(P＞0.05). Furthermore, comparewith the dose and volume parameters of each target when the irradiationboundary(ENI and IFI) different, found that the ENI group’s irradiated dose ofGTV、CTV、PTV and the volume of CTV-V55～50and PTV-V60～50were higherthan IFI group, with a statistically significant difference. Further to comparethe dose、volume parameters of ENI and IFI in the local region failure group,found that CTV-D98%、CTV-D95%、PTV-D98%、PTV-D95%、PTV-D50%of ENI group higher than IFI group, with a statistically significantdifference(P=0.00、0.01；0.00、0.00、0.04). The volume parameters contrastshow that CTV-V55、PTV-V60～50of ENI group aslo higher than IFI group,with a statistically significant difference（P=0.01；0.00、0.00、0.01). Comparethe dose、volume parameters of ENI and IFI in the local region no failuregroup, aslo found that the ENI group’s dose parameters of GTV、CTV、PTVhigher than IFI group, with a statistically significant difference(P=0.04、0.02、 0.01、0.01；0.00、0.00、0.01、0.03；0.00、0.00、0.00、0.02); the volumeparameters of PTV in ENI aslo higher than IFI, the difference havestatistically significant(P=0.01、0.01、0.02). For local failure and no failuretwo groups of layered analysis, compare their dose and volume parameters.Found that when esophageal lesion length≤5cm, the failure group doseparameters CTV-D98%、PTV-D98%、PTV-D95%and volume parametersPTV-V60both lower than no failure group, the difference was statisticallysignificant(P=0.04;0.01、0.03;0.04); When the esophageal primary tumor GTV＜30cm3, the failure group dose parameters PTV-D98%、PTV-D95%wereboth lower than the no failure group, the difference has statisticallysignificant(P=0.01、0.04); When the clinical stage T1+2, the failure group doseparameters PTV-D98%was aslo lower than the no failure group, thedifference was statistically significant(P=0.02); When the clinical stage N0, thefailure group volume parameters PTV-V60was lower than the no failuregroup, the difference was statistically significant(P=0.02); When the clinicalTNM stage Ⅰ, the failure group dose parameters PTV-D98%was lower thanthe no failure group, the difference has statistically significant(P=0.04).4The dosimetry analysis of esophageal local lesion failure and no failureafter definitive radiotherapyThe esophageal local lesion uncontrol or recurrent were47cases,50caseswithout esophageal uncontrol or recurrence, compare the two groups’ GTV、CTV、PTV dose and volume, both no statistically significant difference(P＞0.05). Furthermore to compare with the dose and volume parameters of eachtarget when different irradiation boundary(ENI group and IFI group), the ENIgroup’s irradiated dose of GTV、CTV、PTV and the dose volume of PTV werehigher than IFI group, with a statistically significant difference. Furthermore tocompare the parameters between ENI group and IFI group in the esophageallesion relapse group, found that the dose parameters D98%、D95%of CTV、PTV in ENI group higher than IFI group, with a statistically significantdifference(P=0.02、0.04；0.00、0.00）; Volume parameters PTV-V60、PTV-V55of ENI group greater than IFI group, also with a statistically significant difference(P=0.04、0.01）. Compare the parameters between ENI group and IFIgroup in the esophageal lesion no relapse group, the ENI group’s doseparameters CTV-D98%、CTV-D95%、PTV-D98%，PTV-D95%were higherthan IFI group, close to a statistically significant difference(P=0.07、0.07；0.06、0.06), the volume parameters between two groups did not show any statisticallysignificant difference(P＞0.05). Layered analysis between the esophageallesion local relapse group and no relapse group, compare their dose and volumeparameters. Found that when irradiate by IFI, the volume parameters V60ofGTV、CTV、PTV in relapse group show lower than no relapse group, with astatistically significant difference(P=0.046、0.037、0.046); When theesophageal primary tumor GTV≤30cm3, the dose parameters CTV-D98%、CTV-D95%、PTV-D98%、PTV-D95%of relapse group were lower than norelapse group, the difference of CTV-D98%、CTV-D95%was statisticallysignificant(P=0.03、0.04)and the difference of PTV-D98%、PTV-D95%wasclose to statistically significant(P=0.06、0.05); When clinical stage N0, therelapse group volume parameters CTV-V60、PTV-V60show lower than the norelapse group, close to a statistically significant difference(P=0.07、0.06);When uncombined with chemotherapy in clinic, the relapse group doseparameters D98%、D95%、D95%、D2%of GTV、CTV show lower than norelapse, close to a statistically significant difference.Conclusions:1The elective nodal prophylactic irradiation of esophageal carcinomadefinitive radiotherapy could give higher dose prescription and greater volumeof dose presprescription to these treatment targets(GTV、CTV、PTV）, so it maydecrease the local region failure and/or local replapse.2When the primary lesion of esophageal being smaller, early stage andwithout receiving the chemotherapy, all these patients maybe gain the bettereffect from the elective nodal prophylactic irradiation.