Changes in Liver Volume Observed Following Sorafenib and Liver Radiation Therapy

Abstract

The purpose of this study was to quantify unexpected liver volume reductions in patients treated with sorafenib prior to and during liver radiation therapy (RT). Fifteen patients were treated in a phase 1 study of sorafenib for 1week, followed by concurrent sorafenib-RT (in 6 fractions). Patients had either focal cancer (treated with stereotactic body RT [SBRT]) or diffuse disease (treated with whole-liver RT). Liver volumes were contoured and recorded at planning (day 0) from the exhale CT. After 1week of sorafenib (day 8), RT image guidance at each fraction was performed using cone beam CT (CBCT). Planning liver contours were propagated and modified on the reconstructed exhale CBCT. This was repeated in 12 patients treated with SBRT alone without sorafenib. Three subsequent patients (2sorafenib-RT and 1 non-sorafenib) were also assessed with multiphasic helical breath-hold CTs. Livervolume reductions on CBCT were observed in the 15 sorafenib-RT patients (median decrease of 68cc, P=.02) between day 0 and 8; greater in the focal (P=.025) versus diffuse (P=.52) cancer stratum. Seven patients (47%) had reductions larger than the 95% intraobserver contouring error. Liver reductions were also observed from multiphasic CTs in the 2 additional sorafenib-RT patients between days 0 and 8 (decreases of 232.5cc and 331.7cc, respectively) and not in the non-sorafenib patient (increase of 92cc). There were no significant changes in liver volume between planning and first RT in 12 patients with focal cancer treated with SBRT alone (median increase, 4.8cc, P=.86). Liver volume reductions were observed after 7days of sorafenib, prior to RT, most marked in patients with focal liver tumors, suggesting an effect of sorafenib on normal liver. Careful assessment of potential liver volume changes immediately prior to SBRT may be necessary in patients in sorafenib or other targeted therapies.