Hepatic resection of hepatocellular carcinoma after proton beam therapy: A case report

Despite the widespread use of proton beam therapy (PBT) as locoregional therapy, there is currently a lack of histological evidence about the therapeutic effect of PBT for hepatocellular carcinoma (HCC). We present a case of hepatectomy and histological examination of HCC initially treated by PBT. A 76‐year‐old man with chronic hepatitis C underwent routine ultrasound surveillance, which revealed a 22‐mm HCC in segment 4 of the liver. His hepatic reserve was adequate for surgical resection of the tumor; however, he chose to undergo PBT because of his cardiac disease. The patient received 66 Gy in 10 fractions with no toxicity exceeding grade 1. Six months after completion of PBT, contrast computed tomography showed that the tumor had increased in size to 27 mm, and the marginal part of the tumor, but not the central region, was enhanced. Additionally, two new hypervascular nodules were present in segments 5 and 6. The patient underwent surgical treatment 7 months after PBT. The operation and postoperative clinical course were uneventful. Nine months later, however, computed tomography demonstrated new, small, enhanced nodules in the remnant liver (segments 3, 5 and 6) and sacrum. In conclusion, PBT is a valuable treatment for HCC; however, it is difficult to evaluate therapeutic effect of HCC during the early post‐irradiation period and provide an alternative treatment if PBT is not effective, especially in HCC cases with good liver function.