MR-Guided Adaptive SBRT of Primary Tumor for Pain Control in Metastatic PDAC

Patients not progressing after 8 weeks of standard of care systemic therapy (SoC-CT: minimum doublet chemotherapy) will be included and randomized between arm A, receiving MR-guided adaptive SBRT of the primary tumor combined with continuation of SoC-CT, and arm B, continuing SoC-CT without SBRT. Arm A: The primary tumor is treated with SBRT (6.6 Gy x 5) on a MR-LINAC in breath-hold technique. This scheme was shown to have a reasonable toxicity profile on a conventional LINAC. A low toxicity profile is even more important in patients with metastatic and therefore definitively incurable cancer. Therefore, treatment is performed on a MR-LINAC to deliver high doses to the tumor while keeping the toxicity profile as low as possible. For this purpose, daily adaptive planning is performed aiming to maintain stringent dose constraints for organs at risk (duodenum / stomach / bowel / kidney). Chemotherapy will be continued after SBRT. Arm B: Continuing SoC-CT (according to clinical routine appr. 2 weeks after the previous cycle) without SBRT.