A prospective feasibility study of respiratory-gated proton beam therapy for liver tumors.

Purpose: To evaluate the feasibility of a respiratory-gated proton beam therapy for liver tumors.

Methods And Materials: Fifteen patients were enrolled in a prospective institutional review board-approved protocol. Eligibility criteria included Childs-Pugh A/B cirrhosis, unresectable biopsy- proven hepatocellular carcinoma (HCC), intrahepatic cholangiocarcinoma (ICC), or metastatic disease (solid tumors only), 1-3 lesions, and tumor size of ≤6 cm. Patients received 15 fractions to a total dose of 45-75 GyE [gray equivalent] using respiratory-gated proton beam therapy. Gating was performed with an external respiratory position monitoring based system.

Results: Of the 15 patients enrolled in this clinical trial, 11 had HCC, 3 had ICC, and 1 had metastasis from another primary. Ten patients had a single lesion, 3 patients had 2 lesions, and 2 patients had 3 lesions. Toxicities were grade 3 bilirubinemia-2, grade 3 gastrointestinal bleed-1, and grade 5 stomach perforation-1. One patient had a marginal recurrence, 3 had hepatic recurrences elsewhere in the liver, and 2 had extrahepatic recurrence. With a median follow-up for survivors of 69 months, 1-, 2-, and 3-year overall survivals are 53%, 40%, and 33%, respectively. Progression-free survivals are 40%, 33%, and 27% at 1, 2, and 3 years, respectively.

Conclusions: Respiratory-gated proton beam therapy for liver tumors is feasible. Phase 2 studies for primary liver tumors and metastatic tumors are underway.