The Analysis Of Optimal Dose Of Thoracic Radiotherapy For The Patients With Extensive Stage Small Cell Lung Cancer

Aims To explore and analyse the optimal dose ranges of thoracic radiotherapy for the patients with extensive stage small cell lung cancer.Methods A retrospective analysis was performed among patients pathology or cytologically diagnosed with ES-SCLC between February 2010,and October2015.all Patients received etoposide + cisplatin or etoposide + carboplatin(EP/EC)first-line induction chemotherapy.the 216 patients without progression after first-line induction chemotherapy was apportioned to TRT treatment(N=180)group and chemotherapy(CT)alone(N=36)group.According to the characters of the biological equivalent dose distribution,all patients was apportioned to A group(31.3-40.2Gy,N=23),B group(46.0-46.8Gy,N=38),C group(49.5-53.7Gy,N=43),and D group(55.1-60.6Gy,N=76).For the subgroup analysis,the lower dose group(31.3-46.8Gy,N=61)and higher group(49.5-60.6Gy,N=119)was divided.Results For the whole patients,the median survival time(MST)was 13.2months.the MST were 8.3?11.0?15.8?17.8?8.1 months for in the group A?B?C?D ? CT alone,respectively(P<0.001).The A and B or CT groups the survival parameters were similar(P=0.172,P=0.495).similarly,the C and D the survival parameters were similar(P=0.624).The B group significantly longer than the CT alone group(P=0.020).what's more,here was significant difference between C or D and A,B,or CT alone groups(P < 0.05,all).The median survival time progression-free survival(PFS)all patients was 13.2months.the median PFS were6.5?7.6?11.8?12.4?6.1 months for in the group A?B?C?D?CT alone,respectively(P<0.001).The A and B or CT groups the survival parameters were similar(P=0.588,P=0.668).And,the C and D the survival parameters were similar(P=0.627).The B group significantly longer than the CT alone group(P=0.070).what's more,there was significant difference between C or D and A,B,or CT alone groups(P < 0.02,all).The dose and the metastatic lesions were independent predictors of OS?PFS,and the Concurrent chemoradiotherapy only were independent predictors of PFS.By propensity score matched(PSM)analysis,the results shows that the median OS,PFS and were 10.9,7.4 months for the low dose(N=50)compared with 17.5(P=0.045),10.7months(p=0.014)for high dose radiotherapy(N=50).Finally,there was 142 patients develop progress after treatment,and local regional progress was observed in 64 patients(118/180,35.6%).118 cases(118/180,65.6%)was distant metastasis.In local regional failure mode,the four groups are mainly within the radiation field failure(75%,71.4%,70%,68.8%),and there were few out-radiation field failure(12.5%,28.5%,20%,28.5%).Conclusion The optimal does of the thoracic radiotherapy should be given High dose(49.5 to53.7Gy),the low dose(?40.2Gy)does not improve the survival over the chemotherapy alone treatment,higher(?55.1Gy)dose could not gain more benefits.