Effectiveness of proton beam therapy on liver metastases of esophageal cancer: report of a case.

A 53-year-old man with multiple liver metastasis of esophageal cancer underwent four courses of chemotherapy. After four courses of chemotherapy, positron emission tomography showed progressive disease. Because it was difficult to control the cancer only by chemotherapy, we performed proton beam therapy (PBT) combined with chemotherapy. The irradiated parts were the primary tumor, liver metastases (S2/S4/S6), and mediastinal lymph nodes. The primary tumor including the mediastinal lymph nodes and the S2/S4/S6 metastases received proton beam irradiation at a total dose of 68.2 Gy in 31 fractions and 66.0 Gy in 30 fractions, respectively, according to tumor location. This resulted in a complete response as shown by positron emission tomography. In our experience, PBT exerted a curative effect on liver metastases of esophageal cancer. It is thought that PBT may be effective in the treatment of esophageal cancer. This is the first report about PBT for liver metastases of esophageal cancer.