Study on delineation of tumor volume of primary locally advanced nasopharyngeal carcinoma after induction chemotherapy / 中华放射肿瘤学杂志

ABSTRACT

ObjectiveTo investigate the delineation of gross tumor volume (GTV) in locally advanced nasopharyngeal carcinoma (LANC) according to imageological changes before and after induction chemotherapy (IC) in order to decrease high dose area and protect normal tissue better.MethodsBetween Mar 2010 to Jan 2011,11 patients with LANC were enrolled and treated with TPF regimen followed by intensity-modulated radiotherapy (IMRT) with concurrent chemotherapy,target volumes were delineated based on fused CT imaging before and after IC following project determination.Tumor target volumes after and before IC were respectively delineated according to imaging tumor residues and were overlaid by CTVnx in order to ensure radical doses for the imaging tumor volume before IC,the resulting differences of tumor target volumes of IC before and after were measured and analyzed by paired t-test.ResultsBefore and after IC,the average volumes of GTVnx were respectively 44.72 cm3 and 28.87 ( t =3.89,P =0.003 ),the average volumes of GTVnd were respectively 32.76 cm3 and 19.82 cm3 ( t =2.47,P =0.033 ),the volumes of maximum dose area in brainstem and spinal cord as well as eyeball decreased ( t =2.93-4.59,all P ＜0.05).ConclusionsLANC treated by 3 cycle TPF regimen followed by IMRT with concurrent chemotherapy showes significant shrinkage of tumor volume.The volume of high dose region which caused by normally recovered tissues were decreased by re-delineation of target volume in brainstem and spinal cord as well as eyeball of CT images after IC.