The potential of 4π radiotherapy: a comprehensive SANRA-compliant narrative review of advancements and challenges

4π radiotherapy is an innovative technique in oncology that leverages non-coplanar beam arrangements to enhance tumor targeting while minimizing exposure to surrounding organs at risk (OARs). Compared to conventional techniques such as VMAT, IMRT and SBRT, this approach promises superior dosimetric results. However, its clinical advantages and potential risks, particularly increased integral dose and its implications for secondary malignancies, require thorough evaluation. A comprehensive literature review was conducted using PubMed on August 1st, 2024, to identify studies examining 4π radiotherapy. Keywords included “4π radiotherapy,” “non-coplanar radiotherapy,” “VMAT,” “IMRT,” and “stereotactic body radiation therapy (SBRT).” Studies were included if they assessed dosimetric comparisons between 4π and other techniques or reported on clinical outcomes. Two independent reviewers screened and selected studies, resolving discrepancies through discussion. A total of 18 papers were included in this review. The review revealed that 4π radiotherapy significantly improves dosimetric parameters, including better dose conformity, reduced dose spillage, and enhanced sparing of OARs such as the heart, lungs, liver, and spinal cord. Its application across various cancers, including glioblastoma, prostate, and head-and-neck cancers, showed improved tumor coverage and potential for dose escalation without increasing toxicity. Advanced optimization techniques, such as automated planning, further enhanced treatment quality and delivery efficiency. However, concerns about increased integral dose, which could elevate the risk of secondary malignancies, particularly in long-surviving patients, were highlighted. These findings underscore the importance of careful patient selection and long-term monitoring in clinical settings. 4π radiotherapy offers substantial potential to improve treatment outcomes by enhancing tumor coverage and sparing healthy tissues more effectively than conventional techniques. Future research should evaluate long-term clinical outcomes and develop strategies to minimize integral dose exposure, ensuring the safe and effective integration of 4π radiotherapy into routine clinical practice.