Simulation-free palliative radiotherapy using diagnostic CT scans- is less more? A systematic review.

Background: Cancer incidence continues to rise globally, with nearly half of patients requiring radiotherapy. Simulation-free radiotherapy (SFRT) using diagnostic CT scans instead of dedicated planning CTs is a streamlined alternative that may reduce patient visits and shorten time to treatment without impacting quality of care. This systematic review evaluates the practical aspects, dosimetric accuracy, and clinical outcomes of SFRT in palliative radiotherapy. Methods: Following PRISMA guidelines, PubMed and Embase were searched for publications on SFRT using multiple search terms. Included studies reported clinical or logistical endpoints such as treatment timing, toxicity, dosimetric errors, and patient-reported outcomes. Results: Eleven studies met inclusion criteria, comprising retrospective and prospective cohorts with patient numbers ranging from 10 to 1000. SFRT was associated with significantly reduced intervals from consultation to treatment start compared to conventional workflows. Dosimetric uncertainties using diagnostic CT scans were generally low, with higher variability observed in thoracic cases. Patient selection typically excluded treatments involving steep dose gradients, reirradiation, or requiring immobilization devices. Limited clinical outcome data showed favourable toxicity profiles and effective symptom relief. Conclusions: SFRT offers a practical, efficient alternative for palliative radiotherapy, enabling faster treatment initiation and optimized resource use without compromising safety or efficacy in selected patients. The overall dosimetric accuracy appears acceptable for most cases, though caution is advised for thoracic lesions and complex treatment plans. Additional prospective studies with robust clinical endpoints are needed to further validate the role of SFRT in palliative radiotherapy.