Proton beam radiation as salvage therapy for bilateral colorectal liver metastases not amenable to second-stage hepatectomy

Background Bilobar colorectal liver metastases (CRLM), are now aggressively managed in a multidisciplinary fashion with a two-stage hepatectomy; however, up to 30% of patients are not candidates for second stage hepatectomy. In this report, we describe a novel technique of delivering ablative radiation to the entire right hemiliver by using proton therapy in a series of patients. Methods A data base of patients undergoing entire right hemiliver ablative radiation was maintained prospectively. Clinical, pathologic and treatment characteristics were collected for these patients. Survival duration was calculated from end of radiation. Radiation was delivered with proton therapy using deep inspiratory breath hold (DIBH) and a phase contrast simulation CT scan. Results All five patients tolerated radiation treatment well. All four patients treated with biologic equivalent dose (BED) >89.6 Gy achieved partial or complete radiographic response and in-field local control at last follow up. Two patients are alive and without evidence of disease. Two patients experienced disease progression outside of the liver. Conclusion These results suggest that the use of stereotactic proton therapy as a salvage therapy for patients with CRLM not amenable to second stage hepatectomy may achieve good local control and permit an opportunity for long term survival.