A single-institutional experience with low dose stereotactic body radiation therapy for liver metastases

Abstract

Aim: This study reports a single-institutional experience treating liver metastases with stereotactic body radiation therapy (SBRT).

Materials and methods: 107 patients with 169 lesions were assessed to determine factors predictive for local control, radiographic response, and overall survival (OS). Machine learning techniques, univariate analysis, and the Kaplan-Meier method were utilized.

Results: Patients were treated with a relatively low median dose of 30 Gy in 3 fractions. Fractions were generally delivered once weekly. Median biologically effective dose (BED) was 60 Gy, and the median gross tumor volume (GTV) was 12.16 cc. Median follow-up was 7.36 months. 1-year local control was 75% via the Kaplan-Meier method. On follow-up imaging, 43%, 40%, and 17% of lesions were decreased, stable, and increased in size, respectively. 1-year OS was 46% and varied by primary tumor, with median OS of 34.3, 25.1, 12.5, and 4.6 months for ovarian, breast, colorectal, and lung primary tumors, respectively. Breast and ovarian primary patients had better OS (p < 0.0001), and lung primary patients had worse OS (p = 0.032). Higher BED values, the number of hepatic lesions, and larger GTV were not predictive of local control, radiographic response, or OS. 21% of patients suffered from treatment toxicity, but no grade ≥3 toxicity was reported.

Conclusion: Relatively low-dose SBRT for liver metastases demonstrated efficacy and minimal toxicity, even for patients with large tumors or multiple lesions. This approach may be useful for patients in whom higher-dose therapy is contraindicated or associated with high risk for toxicity. OS depends largely on the primary tumor.

Keywords: Dose-fractionation; Liver; Metastasis; SABR; SBRT.