Pulmonary Magnetic Resonance-guided Online Adaptive Radiotherapy of Locally Advanced Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is very common and carries the highest mortality of all malignant diseases (350.000 - 400.000 deaths per year in the European Union). In specific, the 5-year overall survival rate of locally-advanced NSCLC (LA-NSCLC) is merely 20%. One reason for this dismal prognosis is the lack of effective treatment options. Since most patients with LA-NSCLC are not candidates for a tumor resection, definitive (chemo)radiotherapy (C)RT with consecutive immunotherapy (IT) is the treatment of choice according to national and international guidelines. However, local tumor relapse remains a major pattern of recurrence in approx. 30% of cases. Furthermore, many patients cannot benefit from chemotherapy due to multiple comorbidities, and application of IT requires an initial tumor response to (C)RT and absence of higher-grade pulmonary toxicity. Consequently, radiotherapy is a cornerstone in the locally ablative treatment of LA-NSCLC and essentially influences the course of the further treatment. MR-guided radiotherapy is an innovative technique which supports sophisticated approaches towards pulmonary adaptive radiotherapy (ART). Such adaptive radiation approaches allow highly individualized thoracic radiotherapy with dose distributions tailored to the interfractional changes in tumor geometry and anatomy of surrounding OARs. Therefore, MR-guided ART has the potential to optimize the balance between intensified target volume dose and sparing of vulnerable OARs. This prospective, multicenter clinical trial is desinged to demonstrate the clinical feasibility and gain first data on the safety of MR-guided online ART to LA-NSCLC. Based on the investigators extensive experience with MR-guided RT of early-stage NSCLC and lung metastases, the invesitgators hypothesize that MR-guided online ART to LA-NSCLC can be performed successfully in ≥ 80% of patients with a mean time \< 90 minutes. The investigators plan to include 30 patients with LA-NSCLC in Union for International Cancer Control (UICC) stage IIIA-C at three German university hospitals (Uniklinikum Heidelberg, Uniklinikum LMU München, Uniklinikum Tübingen). Patients will receive MR-guided online ART, which includes gated dose delivery as well as online plan adaptation once weekly or in case major anatomical changes are detected on daily MR-imaging. Patients will be followed-up to assess toxicity, tumor control (by means of thoracic CT- and MR-imaging) and patient-reported outcomes for 24 months after treatment.