Clinical Outcomes And Treatment Planning Strategies For Advanced-Stage Non-Small Cell Lung Cancer (Nsclc) Treated With Intensity Modulated Radiation Therapy (Imrt) And Concurrent Chemotherapy (Cct)

IMRT has been used in our institution to treat locally advanced NSCLC patients for whom normal tissue constraints could not be met using 3D conformal radiotherapy (3DCRT). The purposes of this study are 1) to review the clinical outcomes of this patient cohort; and 2) to establish corresponding clinical guidelines for IMRT treatment planning. Clinical data were reviewed for lung cancer patients treated with IMRT at our institution from 2002 to 2005. The patient cohort included those who had Stage III-IV NSCLC, and who had definitive concurrent chemoradiation. Patients were excluded if they had a history of major lung surgery, prior chest radiotherapy, or mixed 3DCRT and IMRT plans. Clinical outcomes and major toxicities including pneumonitis and esophagitis were analyzed based on medical records and clinical follow-up. IMRT treatment plans and dosimetric parameters were reviewed. Guidelines for IMRT treatment planning were developed based on the existing clinical outcome and dosimetry data. In total, 83 patients were included in this study, 93% of whom were Stage III NSCLC. The histology types were adenocarcinoma (36%), squamous cell (35%), and unspecified non-small cell (29%). 59% of patients were treated to a dose range of 63–66 Gy, with the rest treated above 66 Gy (23%), or within 60–63 Gy (18%). The median follow-up time was 10 months (range, 1.1–43.8 months). The 18 month locoregional control, disease free survival, and overall survival were 63%, 38%, and 62%, respectively. The rate of grade 3 and higher treatment-related pneumonitis at 12 months was 11%. The rate of grade 3 and higher acute esophagitis was 35%. In achieving effective IMRT treatment plans, mean lung dose and the volume of normal lung receiving low-dose radiation were used as important constraints to minimize pulmonary toxicity. The number of IMRT beams was limited within the range of 5–7, with the beam angles being carefully selected to spare healthy lung. The other physical parameters that affected low-dose radiation and were thus considered during IMRT treatment planning included the number of MLC segments and monitor units used. IMRT may be effective in treating advanced NSCLC with concurrent chemotherapy. Dose distributions for IMRT treatments need careful planning considering normal tissue toxicity and minimization of exposure to healthy lung.