Stereotactic body radiotherapy in rare cancers

Stereotactic Body Radiotherapy (SBRT) is an emerging treatment option, delivering highly focused radiation dose with an extremely hypofractionated, ablative dose schedule. SBRT may be of particular interest in rare tumors (less than 15/100.000 cases per year), for whom available systemic treatment options are limited. In this thesis, use of SBRT has been investigated in the setting of rare malignancies, either primary tumor (Locally Advanced Pancreatic Cancer), locoregional metastases (lymphnodal metastases from non-prostate primary tumor, LN) and distant metastases (Soft Tissue Sarcoma, STS) . In the LAPC group, additional daily imaging was obtained from a hybrid treatment unit constituted by a Cyberknife integrated with an CT-scanner on rails in order to extract information on daily anatomical variation, suggesting an impact on dose to organs at risk and treatment-related toxicity: a model was built to predict patterns of motion and deformation of organs at risk. A retrospective analysis was conducted on patients affected by LN and STS metastases, showing satisfactory disease control rates with a favorable toxicity profile. The role of SBRT in rare malignancies as a treatment option for primary tumors, locoregional nodal metastases and distant metastases was discussed with an outlook on future research, particularly with regard to the challenge of inter-fractional anatomic variations in critical locations.