Palliative Care

PD 02 - Palliative 1 - Poster Discussion

1010 - Proton SBRT for Liver Metastases - Results of 5-year Experience for 80 Hepatic Lesions Based on NRG-BR001

Sunday, October 21
1:21 PM - 1:27 PM
Location: Room 217 C/D

Proton SBRT for Liver Metastases - Results of 5-year Experience for 80 Hepatic Lesions Based on NRG-BR001
D. C. Sufficool, P. McGee, S. Swenson, C. T. Hsueh, G. Nagaraj, M. E. Reeves, J. D. Slater, and G. Y. Yang; Loma Linda University Medical Center, Loma Linda, CA

Purpose/Objective(s): To evaluate local control outcomes of liver metastases treated with proton stereotactic body radiation therapy (SBRT). Secondary objectives include evaluation of toxicity.

Materials/Methods: Patients diagnosed with metastatic disease to the liver treated with proton SBRT between 2012-2017 per NRG-BR001 study of SBRT for the treatment of multiple metastases were included. Tumor motion was accounted for using either respiratory management or 4D CT scan. Important aspects of plan assessment included dose restricting when close to bowel and keeping V15 (volume of liver receiving at least 15 Gy) or V21 less than 700cc's of normal liver in 3 or 5 fraction plans respectively. In-field local control was evaluated according to RECIST 1.1 criterion. Radiation induced liver disease was evaluated using CTCAE 5.0 criteria.

Results: A total of 41 patients with 80 lesions were included in this analysis with a median age of 65.5 years (range 33-87). Dose/fractionation included 50Gy / 5 fractions (19%), 30Gy / 5 fractions (16%), and 30Gy / 3 fractions (16%). The primary cancer site was 51% colorectal, 17% breast, and 33% other. The mean number of metastases treated was 1.7 (range 1-5) with mean tumor diameter of 2.7 cm ± 1.6 cm (range 0.7 – 7.3). With a mean follow up of 14.5 months (range 1 – 44), local control at 6 months and 1 year was 92% and 75%, respectively. No radiation induced liver disease was detected. Grade 1 and grade 2 toxicities were 38% and 6% respectively. No patient developed grade 3 or higher toxicity. Predicted liver toxicity was minimal, with median V15 of 205cc (interquartile range; IQR 137-235) and median V21 of 155cc (IQR 64 – 236) for 3 and 5 fraction plans respectively.

Conclusion: Proton SBRT for liver metastases demonstrated a high rate of local tumor control with minimal toxicity. The integral dose advantage allows patients to have multiple courses of full dose therapy while still maintaining liver dose constraints. This is especially important as out of field liver metastases are one of the most common sites of recurrence or progression in these patients.

Author Disclosure: D.C. Sufficool: None. P. McGee: None. S. Swenson: None. M.E. Reeves: None. G.Y. Yang: President; Society for GI Oncology.

Daniel Sufficool, MD

Disclosure:
No relationships to disclose.

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