Hypofractionated radiotherapy with tomotherapy for patients with hepatic oligometastases: retrospective analysis of two institutions.

To evaluate the efficacy and toxicity for patients with hepatic oligometastases, receiving hypofractionated radiotherapy with Tomotherapy to the liver. A total of 42 patients with 54 hepatic lesions, who had been treated from 2007 to 2011 at two institutions, were retrospectively reviewed for this study. All the patients received radical resections of the primary tumor, and had been presented with one to two hepatic lesions. The radiation dose of 40-75 Gy in 10-20 fractions (median, 50 Gy in 10 fractions) was delivered for the planning target volume. At a median follow-up time of 15 months, 1- and 2-year local control (LC) rates were 59.9 and 49.0 %, respectively. The 1- and 2-year overall survival (OS) rates were 60.0 and 44.0 %, respectively. Maximal tumor diameter of <3 cm and biologically effective dose (BED) of ≥100 Gyα/β=10 were significantly associated with higher LC and OS. Primary colorectal cancer tended to be associated with higher LC (P = 0.075), and was significantly associated with higher OS (P = 0.037). 12 (28.6 %) of the 42 patients had grade 1-2 toxicities, and grade 3 or higher toxicity did not occur. Hypofractionated radiotherapy with Tomotherapy was safe for patients with hepatic oligometastases. The maximal tumor diameter of <3 cm and BED of ≥100 Gyα/β=10 were significant prognostic factors for higher local control and survival, and primary colorectal cancer patients had statistically higher overall survival than the others.