Prospective study of lung V5 and V10 in predicting radiation-induced lung injury in advanced non-small-cell lung cancer treated with three-dimensional conformal radiation therapy

Objective To analyze the low dose-volume associated with radiation-induced lung injury (RILI) in patients with advanced non-small cell lung cancer (NSCLC) treated by three-dimensional confor-real radiation therapy (3DCRT). Methods Data of 100 patients with histologically proved NSCLC treated with 3DCRT or IMRT between November 2006 and January 2009 were collected. Nine patients treated with radiotherapy alone and 91 with radiotherapy combined with chemotherapy. A median dose of 70 Gy (range,60-80 Gy) was delivered with late-course accelerated hyperfractionated radiotherapy (LAHRT). Twenty-four patients received dose of 61-69 Gy and 76 received more than 70 Gy. The V5 ,V10 ,V20 ,V30and mean lung dose (MLD) were calculated from the dose volume histogram system. The RILI was evaluated according to Common Toxicity Criteria 3.0(CTC 3.0). Results The range of V5, V10, V20 and V30 was 37%-98%,27%-78%, 17%-54% and 9%-31%, respectively, with a median value of 65%, 47.5%, 31% and 24%, respectively. The acute RILI of grade 1, 2, 3, 4 and 5 was observed in 34, 27, 8, 1 and 1 patients,respectively. The chronic RILI of grade 1, 2 and 3 was observed in 46, 14 and 2 patients, respectively. V5,V10, V20 and MLD were significantly correlated with acute RILI of ≥ grade 1. V5, V20, V30 and MLD were significantly correlated with acute RILI of ≥ grade 2. The acute RILI of ≥ grade 2 was significantly in-creased when V5, V20 and V30 were more than 65%, 31% and 24%, respectively. The acute RILI of ≥ grade 3 was significantly increased when V5 was more than 65%. The acute RILI of ≥ grade 1 was signifi-candy increased when V20was more than 31%. The gross tumor volume and planning target volume were sig-nificantly correlated with the acute RILI of ≥ grade 1 and chronic RILI of ≥ grade 2. Conclusions The dose-volume Vs and V10 are effective in predicting RILI Key words: Carcinoma,non-smaU cell lung/radiotherapy ;  Radiotherapy,late-course accelerated hyperfraction;  Radiotherapy, three-dimensional conformal ;  Dose volume histogram;  Radiation-induced lung injury