Hypofractionated stereotactic body radiation therapy (SBRT) for limited hepatic metastases

Purpose: To evaluate the feasibility and efficacy of hypofractionated stereotactic body radiation therapy (SBRT) for the treatment of liver metastases.

Methods and Materials: The records of 69 patients with 174 metastatic liver lesions treated with SBRT between April 2001 and October 2004 were reviewed. The most common primary tumors were colorectal (n = 20), breast (n = 16), pancreas (n = 9), and lung (n = 5). The mean number of lesions treated per patient was 2.5 (range, 1–6). The longest diameter of the lesions ranged in size from 0.6 to 12.2 cm (median, 2.7 cm). Dose per fraction ranged from 2 Gy to 6 Gy, with a median total dose of 48 Gy (range, 30–55 Gy). Dose was prescribed to the 100% isodose line (IDL), with the 80% IDL covering the gross tumor volume with a minimum margin of 7 mm.

Results: The median follow up was 14.5 months. Sixty patients were evaluable for response based on an abdominal computed tomography scan obtained at a minimum of 3 months after completion of SBRT. The actuarial overall infield local control rate of the irradiated lesions was 76% and 57% at 10 and 20 months, respectively. The median overall survival time was 14.5 months. The progression-free survival rate was 46% and 24% at 6 and 12 months, respectively. None of the patients developed Grade 3 or higher toxicity.

Conclusion: Hypofractionated SBRT provides excellent local control with minimal side effects in selected patients with limited hepatic metastases.

Keywords: Liver metastases, Oligometastases, Tolerance, Novalis radiosurgery, Stereotactic body radiation therapy