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MO_16_2890 - Outcomes of whole brain radiation with simultaneous in-field boost (SIB) for the treatment of brain metastases

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Outcomes of whole brain radiation with simultaneous in-field boost (SIB) for the treatment of brain metastases
J. Zhong1, A. Waldman2, S. Kandula3, B. R. Eaton1, R. S. Prabhu4, S. B. Huff5, I. R. Crocker1, and H. K. G. Shu1; 1Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, GA, 2Emory University School of Medicine, Atlanta, GA, 3Florida Hospital Medical Group, Radiation Oncology Associates, Orlando, FL, 4Levine Cancer Institute, Atrium Health and Southeast Radiation Oncology Group, Charlotte, NC, 5University of Carolina, Chapel Hill, NC

Purpose/Objective(s): Several prospective studies have demonstrated increased local control with the addition of a stereotactic radiosurgery (SRS) boost with whole brain irradiation (WBRT) in patients with brain metastases. However, the clinical application of SRS boost can be limited by several factors, including large tumor size, large numbers of lesions, and patient inconvenience from multiple SRS sessions. Here, we investigate the feasibility and outcomes using WBRT with a simultaneous integrated boost (SIB) to visible lesions in patients with ten brain metastases or fewer.

Materials/Methods: From 2011 to 2016, patients were prospectively enrolled after institutional review board (IRB) approval. Patients were prescribed a dose of 37.5 Gy to the whole brain with a SIB to 52.5 Gy to the gross lesions in 15 fractions or 25 Gy to the whole brain with a SIB to 45 Gy in 10 fractions. All plans were optimized for dose coverage of the whole brain and lesions using volumetric arc therapy (VMAT). Patients were evaluated with high resolution MRI for treatment and follow-up, and neurocognitive and quality of life assessments were conducted at baseline and at follow-up.

Results: Thirteen patients were enrolled and treated on this protocol. The median patient age was 55 years (range 35-73), and the median number of gross lesions was 6 (range 2-10). The average lesion size was 2.4 cm3 (range 0.6-49.9 cm3). Eleven patients were prescribed 25 Gy/45 Gy to the whole brain/gross lesions in 10 fractions, and two patients were prescribed 37.5 Gy/52.5 Gy in 15 fractions. The median follow-up period is 11 months. The 1-year local control rates were 92% at the patient level, and 98.6% at the lesion level. The overall 1-year intracranial control was 46%. No patients developed leptomeningeal disease. 15% of patients experienced asymptomatic radiation necrosis, and no patient experienced grade 2 or higher radiation necrosis. The median maximum dose (DMax) and D100 to the hippocampus was 28.6 Gy and 24.8 Gy, respectively. Patients had no significant declines in Mini-Mental State Examination (MMSE), Hopkins Verbal Learning Test-Revised (HVLT-R), and Medical Outcomes Study (MOS) Cognitive Functional status scores between baseline and post-treatment assessment times.

Conclusion: WBRT with SIB to gross lesions using VMAT planning appears to be safe and effective in the treatment of patients with up to ten brain metastases. Cognitive function did not appear to be significantly reduced following treatment. This treatment strategy should be considered in those patients with a high number of metastases or ones not amenable for radiosurgery.

Author Disclosure: J. Zhong: None. A. Waldman: None. R.S. Prabhu: None. S.B. Huff: None. I.R. Crocker: None. H. Shu: Honoraria; Varian Medical Systems. Speaker's Bureau; Varian Medical Systems. Travel Expenses; Varian Medical Systems. Stock; Medtronics, Apple. Chairman; QIN CTTDWG. Co-Chairman; NCI-QIRT Working Group.

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