Proton Beam Therapy for Multifocal Hepatocellular Carcinoma (HCC) Showing Complete Response in Pathological Anatomy After Liver Transplantation

We describe a patient with multifocal recurrent hepatocellular carcinoma (HCC) who received proton beam therapy (PBT) and then underwent donation after brain dead (DBD) liver transplantation. The anatomy of the explanted diseased liver was examined pathologically post-transplantation. The patient was a 52-year-old male with hepatitis B virus infection and liver cirrhosis of Child-Pugh class B. Right lobe and caudate lobectomy were performed for primary HCC. However, three recurrent tumors appeared in the remnant liver in segments S2 (two sites) and S4, of sizes 23 mm, 10 mm, and 32 mm, respectively. Liver transplantation was required due to these multiple HCCs and liver cirrhosis, but the patient was ineligible for living donor liver transplantation (LDLT) based on Milan criteria. He was registered as a candidate on the waiting list for DBD transplantation. In consideration of the long waiting time for a deceased donor transplant for more than one year, the progression of multiple recurrent HCCs, and the risk of death, the patient had limited treatment options other than PBT for poor liver function and multifocal HCC and eventually received 65 GyE/18 fractions of PBT. Eleven months after the start of PBT, the tumors remained progression-free and liver function did not deteriorate, allowing the patient to wait for liver transplantation. After transplantation, the histopathology of the explanted liver showed that the left lobe of the liver treated by PBT showed no evidence of solid tumors and tumor cells in visual and microscopic examinations. There was also no significant damage to normal liver tissue. This case demonstrates that PBT is a prospective option for patients with HCC with poor liver function, multiple tumors, and no other treatment options. PBT can achieve control or even complete response of HCC while maintaining liver function and may be an effective pre-transplant method for tumor downstaging and prolonging survival. PBT may enable more people to wait for a donor liver or to become eligible for liver transplantation.