Feasibility and Efficacy of Simultaneous Integrated Boost Intensity-modulated Radiation Therapy based on MRI-CT fusion in Patients with Brain Metastases of Non-small Cell Lung Cancer

Purpose: To assess the feasibility and therapeutic effects of simultaneous integrated boost intensity-modulated radiation therapy (SIB-IMRT) based on the fusion imaging of magnetic resonance imaging (MRI) and computed tomography (CT) as a dose-intensive technique in patients with brain metastases (BM) of non-small cell lung cancer (NSCLC). Methods and materials: Forty-six NSCLC patients with 1 to 7 brain metastases were enrolled in this retrospective study between November, 2011 and February, 2017. Thirty-one patients (67.4%) had 1-3 metastases (oligometastases), otherwise, more than 3 metastases were seen in only 15 patients (32.6%). GTV (Gross tumor volume) contouring was based on the fusion imaging of MRI-CT, WBRT was prescribed in 37.5 Gy/15 fractions with a simultaneous boost in the metastatic lesions of 52.5 Gy/15 fractions. Results: The median overall survival (OS) and intracranial progression free survival (PFS) for all the patients were 20.0 months and 11.0 months, respectively. The 6-month and 1-year OS were 87.0% and 69.6% respectively, while the 6-month and 1-year PFS were 78.3% and 43.5% respectively. Until the end of the follow-up, 16 patients (34.8%) were alive. No evidence of intracranial progress or recurrence was found in 6 patients (13.0%) during the follow-up. Conclusion: SIB-IMRT with the dose/fractionation based on the fusion imaging of MRI-CT is feasible and safe. It is beneficial to the NSCLC patients with BM and can reduce the overall costs of treatment.