Comparison of target dosimetry and treatment outcome in patients with stage III non-small cell lung cancer treated with three-dimensional conformal radiotherapy and intensity-modulated radiotherapy

Abstract

Objective To compare the target dosimetric distribution and clinical outcome in patients with stage III non-small cell lung cancer(NSCLC)treated with three-dimensional conformal radiotherapy (3DCRT)and intensity-modulated radiotherapy(IMRT) . Methods The clinical data of 419 patients with stage III NSCLC treated with either 3DCRT or IMRT were retrospectively analyzed. Among them, there were 338 male and 81 female patients, and the median age was 63 years(range: 32-84 years). There were 340patients treated with 3DCRT and 79 with IMRT, and the median prescribed dose was 60 Gy(range: 50-76Gy). One hundred and forty patients were treated with radiotherapy alone and 279 were treated with chemoradiotherapy. The target dosimetric distribution was evaluated with dose-volume histogram(DVH)parameters. The overall survival(OS)rate was calculated using the Kaplan-Meier method and analyzed by the log-rank test. Results When comparing the clinical data, the patients treated with 3DCRT were in older ages, and had advanced N and clinical stages (P=0.01, 0.00, and 0.00, respectively). When comparing the target DVH parameters, the patients treated with IMRT had larger planning target volume(PTV) (P=0.01) , significantly lower clinical target volume(CTV)Dmean, CTV D90, PTV Dmean, and PTV V65-V60 (P=0.05- 0.01) , significantly higher V5-V20 in both lungs, higher esophagus Dmean, longer esophagus in the radiation field, higher linear energy transfer between 45 and 55 keV/µm(LET45-LET55) , and higher spinal cord Dmean (P=0.03 - 0.00). The follow-up rate was 97.4%. After radiotherapy, the 1 -, 3-, and 5-year OS rates were 65.5%, 26.1%, and 18.5%, respectively, and the median survival time was 20 months. There were no significant differences in OS rate and the incidence of acute radiation pneumonitis and radiation esophagitis between patients treated with IMRT and 3 DCRT (P=0.06, 0.73, 0.13). Stratified analysis showed that, when comparing the patients treated with IMRT with those treated with 3DCRT, the survival rate was only lower in male patients, patients in stage T3 -T4 or N0 -N2, and those without chemotherapy (P=0.04, 0.04, 0.02, 0.00) . Conclusions The treatment outcomes of patients with stageⅢ NSCLC undergoing IMRT and 3 DCRT are comparable. IMRT shows a potential dosimetric advantage, but the result needs further investigation. Key words: Lung neoplasms/three-dimensional radiotherapy; Dosimetry; Prognosis