The Effect Of Biologically Effective Dose On The Prognosis Of Nasopharyngeal Carcinoma Patients That Receive IMRT And Stage Of T3 And T4

Objective:In conventional radiotherapy time,with the increase*of the total radiothrapy dose,the local control(LC),distant metastasis-free survival(DMFS)> disease free survival(DFS) and overall survival(OS) rates increase,too.But to the patients who get treated with intensity-modulated radiotherapy(IMRT),whether the local control and survival rates increase by increasing the doseTThis study is to explore the effect of biologically effective dose on the prognosis of nasopharyngeal carcinoma patients.Methods:From January 2010 to December 2010,141 nasopharyngeal carcinoma patients (130 pantients are followed up) staged T3 and T4 received IMRT in the first affiliated hospital of guangxi medical university.The prescription dose delivered to the gross tumor volume of the nasopharynx (GTVnx) was 68-76Gy.Because the total dose,fractionation dose and the radiation times were different,calculate the BED of every patient according to the Linear-quatratic formulation.Count the 5-year LC,regional control(RC), DMFS,DFS and OS rates and the toxicities.Compare the prognosis of different BED groups.Results:1.The 5-year LC,RC,DMFS,DFS and OS rates were 90.9%,94.3%, 86.5%,78.8% and 80.8% respectively.2.In all,25 patients died,and their living time ranged from 2 months to 60 months.The middle time was 33 months.Eight patients died of local or regional recurrence.Fourteen patients died of distant metastasis.One died of hemorrhage of pharyngonasal cavity,and two patients died of other reasons.Fifteen patients had local or regional recurrence.Of them,eight patients had only local recurrence, four patients had only regional recurrence,three patients had both local and regional recurrence.Eleven patients had local recurrence,and the time ranged from 6 months to 49 months,the middle time was 33months.The local recurrence niduses were all in-field recurrence.17 patients had distant metastasis.The time ranged from 3 months to 60 months, and the middle time was 18 months.10 patients had multiple organ metastasis,7 patients had single organ metastasis.3.The 5-year LC,DMFS,DFS and OS rates of low BED group and high BED group were 89.9%vs91.9%,87.1%vs85.9%,77.8%vs79.8% and 80.0%vs 81.5% respectively.P<0.05.The differences were not statistically significant.The toxicites of high BED group patients were more serious than the low BED group patients.Conclusion:1.The nasopharyngeal carcinoma patients who are staged of T3 and T4 have favorable treatment outcome if getting the IMRT.2.If the radiation dose had reached radical therapy dose,no benefit was gained when improving the dose.3.Nasopharyngeal carcinoma patients staged T3 and T4 still have treatment upside potential,more cooperative methods are needed.