Outcome and toxicity of stereotactic body radiotherapy with helical tomotherapy for inoperable lung tumor: Analysis of Grade 5 radiation pneumonitis

To analyze outcomes and toxicities of stereotactic body radiotherapy with helical tomotherapy (ht-sbrt) for inoperable lung tumors,the medical records of 30 patients with 31 lung tumors treated with ht-sbrt were reviewed. the 3-year local control,cause-specific survival and overall survival rates (lc,ccs and os,respectively) were analyzed using the kaplan-meier method. toxicities were graded using common terminology criteria for adverse events ver. 4. to investigate the factors associated with grade 5 radiation pneumonitis (g5 rp),several parameters were analyzed: (i) patient-specific factors (age,gross tumor volume and ptv,and the interstitial pulmonary shadow on pretreatment ct); and (ii) dosimetry-specific factors (conformity index,homogeneity index,mean lung dose,and v5,v10,v15,v20 and v25 of the total lungs). the median duration of observation for all patients was 36.5 months (range,4-67 months). the 3-year lc,ccs and os were 82,84 and 77%,respectively. regarding grade 3 or higher toxicities,two patients (6.7%) developed g5 rp. gtv was significantly associated with g5 rp (p = 0.025),and there were non-significant but slight associations with developing g5 rp for v5 (p = 0.067) and ptv (p = 0.096). ht-sbrt led to standard values of lc,ccs and os,but also caused a markedly higher incidence of g5 rp. it is essential to optimize patient selection so as to avoid severe radiation pneumonitis in ht-sbrt. © 2014 the author 2014. published by oxford university press on behalf of the japan radiation research society and japanese society for radiation oncology.