USE OF HELICAL TOMOTHERAPY FOR HYPOFRACTIONATED TREATMENT OF LIMITED BRAIN METASTASES IN THE INITIAL AND RECURRENT SETTING: A SINGLE INSTITUTION EXPERIENCE

BACKGROUND: Whole brain radiation therapy (WBRT), stereotactic radiosurgery (SRS), or both are commonly employed in the treatment of limited brain metastases in the initial or recurrent setting. Hypofractionated partial volume irradiation is also employed, however published experience using helical TomoTherapy for this purposes is limited. We reviewed our institutional experience to assess patient selection factors, fractionation scheme, and outcomes associated with this technique. METHODS: A retrospective chart review was performed to evaluate patients treated with partial volume hypofractionated helical TomoTherapy-based IMRT for brain metastases at our institution. RESULTS: Thirteen patients (7M/6F, median age 62, median KPS 90) with a limited (1-9) number of brain metastases in the primary or recurrent setting were identified. Primary malignancies included colorectal (3), NSCLC (5), RCC (1), breast (1), melanoma (1), uterine (1) and ovarian (1). The median time from initial diagnosis to identification of brain metastases was 21 months (range 0-61.3 months). Treatment was delivered to intact metastases in 6 patients, to a single resection cavity in 6 patients, and to both in one patient. The median number of intact metastases treated was 2 (range 1-9). The most common fractionation schemes were 25 Gy in 5 fractions and 27.5 Gy in 5 fractions to each lesion. Previous treatments included WBRT (5), WBRT + SRS (3), SRS alone (1), and none (4). At a median of 6 months follow up (range 1.26-20.13 months) after TomoTherapy, 10 patients were deceased, 2 were alive, and one was lost to follow up. Systemic progression occurred in 7 patients and intracranial progression occurred in 5. The median intracranial progression free survival and overall survival after TomoTherapy was 6.3 months. CONCLUSIONS: TomoTherapy-based hypofractionated radiotherapy to a limited number of metastatic lesions is associated with favorable intracranial disease control and survival outcomes in the primary and recurrent setting for select patients.