Clinical Outcome Of [18F] FDG-PET/CT-based Planning For Radiotherapy In Locally Advanced NSCLC

Purpose:To evaluate the clinical outcome and toxicity of radiotherapy (RT) using18F-FDG Positron emission tomography/Computed Tomography ([18F] FDG-PET/CT) in target volume delineation instead of conventional CT for locally advanced non-small cell lung cancer (LA-NSCLC).Methods and Materials:Between Jan2007and May2011,248patients with stage ⅢA or ⅢB NSCLC were referred to our institution for radiotherapy. Among them, four patients were upstaged to stage Ⅳ after PET/CT and excluded, eight patients lost follow-up. The remaining236patients were investigated, including67patients received RT with PET/CT-based planning and169patients with CT-based planning. A propensity score matching (PSM) method (1:1) was utilized to obtain two matched groups:the PET/CT group and CT group. Response to initial treatment, radiation toxicity, and failure pattern were compared between these two groups. The Kaplan-Meier method was used to calculate the overall survival (OS), progression-free survival (PFS), and locoregional control (LRC) for both matched groups. Log-rank test was performed to do the comparison.Results:Two matched groups with comparable baseline clinical characteristics were created using the PSM method, including67patients with PET/CT-based planning (PET/CT group) and67patients with CT-based planning (CT group). Initial treatment was chemo-radiation therapy in52(77.6%) patients and radiotherapy alone in15(22.4%) patients in the PET/CT group, and51(76.1%) patients and16(23.9%) patients in the CT group, respectively. However, patients in the PET/CT group received a higher total radiation dose than those in the CT group (60.7Gy vs.59.0Gy, P=0.067). After initial treatment,55(82.1%) patients in the PET/CT group and41(62.1%) patients in the CT group achieved complete remission (CR) or partial remission (PR), respectively (P=0.010). After a median follow-up of24.7months, a significant superior locoregional control was observed in the PET/CT group compared with the CT group (P=0.036), with a2-year LRC of54.2%and40.1%, respectively. Log-rank test showed no statistically difference between the two matched groups in respect to OS (P=0.319) and PFS (P=0.582). However, patients in the PET/CT group tended to have a slightly longer median survival time (MST) and median progression-free survival time (MPFST). The MST was25.4months in the PET/CT group and21.7months in the CT group, and the MPFST was12.7months and10.7months, respectively. Patients in the PET/CT group were less likely to develop grade≥2radiation-induced pulmonary injury (also termed as symptomatic radiation-induced pulmonary injury, SRILI) than those in the CT group (9.0%vs.19.4%, P=0.083). Other acute toxicities, including acute radiation-induced esophagitis, skin injury, and hematotoxicity, were comparable between the two groups.Conclusions:Using [18F] FDG-PET/CT instead of CT for target volume delineation in radiotherapy for LA-NSCLC was associated with a better LRC and lower incidence of grade≥2radiation-induced pulmonary injury.