RADT-43. TREATMENT OF RETROPERITONEAL LEIOMYOSARCOMA BRAIN METASTASES WITH STEREOTACTIC RADIOSURGERY

Abstract

Abstract INTRODUCTION Retroperitoneal leiomyosarcoma is a relatively rare disease, with infrequent metastatic spread to the CNS. We present the first report of radiosurgical treatment of this disease. METHODS A 49-year-old woman developed leiomyosarcoma of the inferior vena cava and retroperitoneum with lung metastases on diagnosis. Following multiple courses of systemic and operative treatment, she developed a tender ulcerating mass in the left upper maxillary incisor associated with numbness along the upper gum, lip, and premaxillary area. CT revealed a 3.0 cm left posterior alveolar ridge gum lesion with bone invasion, for which she elected to undergo palliative radiation therapy (30 Gy in 10 fractions). Due to potential maxillary nerve involvement altering the intended radiation therapy treatment fields, an orbit/face MRI was performed to better delineate the lesion. On this MRI, two frontal lobe lesions were visualized; subsequent dedicated brain MRI revealed a total of five metastases (0.9 cm right superior frontal gyrus, 0.9 cm left middle frontal gyrus, 0.9 cm right postcentral gyrus, 0.7 cm right occipital, and 1.6 cm left occipital). Consequently, the decision was made to treat the brain metastases with linear accelerator (LINAC) stereotactic radiosurgery (SRS) to allow simultaneous treatment of the maxillary lesion and brain metastases. RESULTS A single CT simulation was performed for her intracranial and extracranial disease, using the Encompass face mask to allow for simultaneous head immobilization and optimal SRS targeting accuracy. LINAC SRS was delivered simultaneously during maxillary lesion radiation therapy to all five lesions (22 Gy to the 80% isodose line) in a single fraction with a 0.2 cm planning target volume (PTV) margin for each lesion. CONCLUSIONS The first reported case of metastatic retroperitoneal leiomyosarcoma brain metastases treated with SRS demonstrates the flexibility of LINAC (rather than Gamma Knife) SRS in allowing for simultaneous treatment of intracranial and extracranial metastatic disease.