[Present state and future of radiation therapy for pancreatic cancer]

According to a nation-wide annual report on pancreatic cancer patients in 1992, 70 percent of patients with pancreatic cancer underwent operations. Thirty percent of them, along with 10 percent of patients who did not undergo operations, underwent radiation therapy. The result of external radiation monotherapy for local advanced pancreatic cancer is so poor that the 2-year survival rate and the median survival time have been reported in some papers to be approximately 10% and at most 13 months, respectively. Our results indicated that the 1-, 2- and 3-year survival rates and the median survival time after external radiation monotherapy for local advanced pancreatic cancer were 21%, 11%, 5% and 11.3 months, respectively. The reasons for the poor results are thought to be as follows: pancreatic cancer is very malignant, invades the surrounding tissues and metastasizes distantly in its earliest stages; it is mostly adenocarcinoma resistant to radiation therapy; and the pancreas borders closely the stomach and duodenum, which are very sensitive to radiation. Therefore, charged particle radiotherapy, especially heavy ion radiotherapy, is expected to bring about advances in the field of radiation therapy for pancreatic cancer because of its excellent potential for dose distribution and biological effect.