Tumor Destructive Mechanical Impulse (TMI) Treatment of Solid Tumors. Part IV: Palliative Management of Painful Bone Metastases, Pain Relief – and Beyond

Vollständiger Abstract

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Background/Aims: Bone metastases are a frequent and highly debilitating complication of advanced malignancies and are associated with severe pain, structural instability and loss of functional capacity. Radiotherapy, systemic antineoplastic therapy, bone-targeted agents and interventional techniques remain the clinical standard, yet a relevant proportion of patients experience only incomplete or transient pain relief. Non-invasive focal approaches are therefore being explored. Tumor-destructive mechanical impulses (TMI) – an umbrella term for shock-type, high-strain acoustic pulses generated by electrohydraulic, electromagnetic or piezoelectric systems – have a long safety record in musculoskeletal medicine and are increasingly investigated in oncology. We report the palliative use of TMI in patients with painful bone metastases. Methods: Patient-specific DICOM data were segmented using Simpleware ScanIP® and imported into ANSYS SpaceClaim for geometry preparation, enabling coupled device-tissue simulations under clinical pressure wave forms; the resulting anatomical models were simulated in ANSYS Explicit Dynamics. In parallel, DICOM data were processed using MATLAB®/TABLIN and converted into OnScale® for high-frequency pressure wave propagation analysis, predicting pressure fields, focal volumes and attenuation through bone. The outputs of the numerical solution of the finite element (FEM) propagation models comprise total energy, energy flux density, pulse count and frequency, and the optimal placement of the TMI applicator. TMI was applied within individual healing attempts in patients in whom conventional therapy had failed. Results: In two patients with metastatic prostate carcinoma described in detail, and in thirteen further patients with bone metastases, TMI applied to metastatic bone lesions was followed by relief of periosteal pain. In both index patients, follow-up Ga-68-PSMA PET-CT showed marked regression of the osseous lesions. Treatments were tolerated without device-related complications; in one patient the piezoelectric technique was not tolerated and was replaced by the electrohydraulic technique. Conclusion: TMI treatment combines direct mechanotransduction with controlled cavitation, potentially disrupting tumor cells and microvasculature and inducing features of immunogenic cell death. In the patients reported here, palliative TMI treatment was associated with pain relief and radiographic tumor regression, including observations compatible with a possible immunological abscopal response. These observations derive from uncontrolled individual healing attempts under concomitant systemic therapy and require prospective confirmation.