Local Control After Stereotactic Body Radiation Therapy for Liver Tumors

PURPOSE: To quantitatively evaluate published experiences with hepatic stereotactic body radiation therapy (SBRT), to determine local control rates after treatment of primary and metastatic liver tumors and to examine whether outcomes are affected by SBRT dosing regimen. METHODS AND MATERIALS: We identified published articles that reported local control rates after SBRT for primary or metastatic liver tumors. Biologically effective doses (BEDs) were calculated for each dosing regimen using the linear-quadratic equation. We excluded series in which a wide range of BEDs was used. Individual lesion data for local control were extracted from actuarial survival curves, and data were aggregated to form a single dataset. Actuarial local control curves were generated using the Kaplan-Meier method after grouping lesions by disease type and BED (100 Gy(10)). Comparisons were made using logerank testing. RESULTS: Thirteen articles met all inclusion criteria and formed the dataset for this analysis. The 1-, 2-, and 3-year actuarial local control rates after SBRT for primary liver tumors (n = 431) were 93%, 89%, and 86%, respectively. Lower 1- (90%), 2- (79%), and 3-year (76%) actuarial local control rates were observed for liver metastases (n = 290, logerank P = .011). Among patients treated with SBRT for primary liver tumors, there was no evidence that local control is influenced by BED within the range of schedules used. For liver metastases, on the other hand, outcomes were significantly better for lesions treated with BEDs exceeding 100 Gy(10) (3-year local control 93%) than for those treated with BEDs of 100 Gy(10) (3-year local control 65%, P < .001). CONCLUSIONS: Stereotactic body radiation therapy for primary liver tumors provides high rates of durable local control, with no clear evidence for a doseeresponse relationship among commonly utilized schedules. Excellent local control rates are also seen after SBRT for liver metastases when BEDs of >100 Gy(10) are utilized.