Effectiveness and safety of 3D lattice radiation therapy in the gluteal region to symptomatically control unresectable synovial sarcoma: A geriatric case report

Abstract

Lattice radiation therapy (LRT) represents an innovative approach in radiation oncology. Unlike conventional radiotherapy, LRT creates an inhomogeneous dose distribution within the tumor, with high-dose regions (vertices) and low-dose regions (valleys), enhancing targeted treatment while minimizing damage to surrounding healthy tissue. Synovial sarcoma is a rare and aggressive malignancy with a poor prognosis, particularly in elderly patients and those with unresectable disease. This case report highlights the use of LRT as a palliative option in a 91-year-old female presenting with a large, symptomatic synovial sarcoma of the left gluteal region, deemed unfit for surgery or systemic therapy. The patient underwent a two-phase radiotherapy approach: an initial single-fraction LRT dose of 12 Gy using the Valencia protocol, followed by conventional volumetric modulated arc therapy (VMAT) delivering 20 Gy in five fractions. The LRT plan incorporated seventeen lattice spheres within the gross tumor volume, achieving high conformity and respecting organ-at-risk constraints. The patient reported substantial pain relief and improved mobility post-treatment, with a follow-up MRI at three months showing a 22.5 % reduction in tumor size. No acute toxicities were noted. This case underscores the potential of LRT as a safe and effective palliative treatment modality for bulky, unresectable sarcomas, offering symptom relief and improved quality of life in patients ineligible for curative interventions. While existing data on the safety of LRT is well-established, and preliminary results regarding its efficacy are promising, the current level of evidence remains low. Therefore, further studies are essential to establish robust evidence supporting the efficacy of LRT.