Simultaneous treatment of two lung cancer lesions with stereotactic MR-guided adaptive radiation therapy: A case report

Lung cancer is 1 of the most prevalent cancers globally. Definitive stereotactic ablative radiotherapy (SABR) is suggested for those who are unfit for or refuse surgical intervention. Here we present a patient with 2 lung cancer lesions who received SABR simultaneously with magnetic resonance Linear accelerator (Linac)-magnetic resonance (MR). PATIENT CONCERNS: A 46-years-old man had history of left lower lung cancer post lobectomy in 2018. Two recurrent tumors were found 2 years following, then became enlarged 4 months later. DIAGNOSES: The recurrent tumors were found by computed tomography. INTERVENTIONS: SABR was indicated due to inoperability and small size. Simulation was done both by computed tomography and MR scan with ViewRay MRIdian Linac, with the prescription dose being 50 gray in 4 fractions performed every other day within 2 weeks. The 2 lesions were irradiated at the same time with a single isocenter with mean treatment time was 78 minutes. OUTCOMES: No acute side effect was noted. Follow-up chest computed tomography scan 14 months after SABR showed mild consolidation and pneumonitis over the upper irradiated site favoring radiation-related reasons, while pneumonitis was resolved over the lower irradiated site. Positron emission tomography showed no definite evidence of FDG-avid recurrence. The patient has survived over 18 months following SABR and more than 4 years from the first diagnosis of lung cancer without significant adverse effects. LESSONS: Simultaneous SABR for multiple lung lesions is quite challenging because tumor motion by breathing can increase the risk of missing the target. With help by MR-Linac, simultaneous SABR to multiple lung lesions can be performed safely with efficacy.