Efficacy and Safety of Simultaneous Integrated Boost Followed by Selective Sequential Boost Radiotherapy for Spinal Metastases: A Single-Arm Retrospective Study.

ObjectiveThis study evaluated the clinical efficacy and safety of simultaneous integrated boost (SIB) followed by selective sequential boost radiotherapy (RT) in patients with spinal metastases (SM) and explored the protocol's potential for dosimetric optimization.MethodsIn this retrospective study, 34 consecutive patients with SM underwent SIB followed by selective sequential boost RT at Peking University Third Hospital between July 2021 and December 2024. Prescribed doses were 30 Gy in 10 fractions to the planning target volume (PTV), with dose escalation to the boost planning target volume (PTV_boost) of either 40 Gy in 10 fractions or 48 Gy in 12 fractions. The primary endpoints included pain relief (Numerical Rating Scale), neurological improvement (Frankel Grade), and adverse events (RTOG/EORTC criteria). Secondary endpoints comprised local control rate (LCR), evaluated by MRI or CT, and cancer-specific survival (CSS).ResultsThe median follow-up was 9.9 months (range: 3.4-44.3 months), and 26 of 34 patients reported pain before treatment; of these, 84.6% (22/26) experienced pain relief (30.8% complete, 53.8% partial). Neurological function improved in 72.7% (16/22) of affected patients, with complete improvement in 27.3% and partial improvement in 45.5%. The majority of adverse events were grade 1-2 and resolved following appropriate symptomatic management. Kaplan-Meier analysis showed LCRs of 97.1%, 90.2%, 90.2%, and 90.2% at 3, 6, 12, and 24 months, respectively, and CSS rates of 97.0%, 97.0%, 87.0%, and 56.8% at the corresponding intervals.ConclusionsIndividualized dose-escalation RT may be a promising treatment for SM, potentially delivering significant pain relief, neurological recovery, and durable local tumor control, all while maintaining strict dosimetric constraints for organs at risk. Further prospective multicenter trials are essential to validate its safety and efficacy.