Radiation therapy for liver metastases.

Liver metastases are a common source of cancer morbidity and mortality and are often the only site of metastases. In the last 2 decades, major technological advancements in radiation treatment planning and delivery have resulted in resurgence in the use of radiation therapy (RT) as a treatment for liver tumors. With the advent of 3-dimensional conformal radiation treatment (CRT), partial liver irradiation became possible. Stereotactic body radiation therapy (SBRT) is a further enhancement, defined as highly focused, stereotactically localized and administered, high-dose RT delivered in a hypofractionated course. There is now more than a decade of experience with CRT and SBRT for the treatment of liver metastases. In selected patients, very high local control rates have been observed, with minimal toxicity. Patients most likely to benefit from RT are those with liver confined disease, focal distribution of metastases, and metastases more than 1.5 cm from luminal gastrointestinal organs. There is growing evidence that strategies using aggressive or ablative local therapies as an adjunct to systemic therapy might achieve improvements in overall outcome as long as they are administered safely.