Studies of intraoperative radiotherapy in carcinoma of the pancreas

Intraoperative radiotherapy (IORT) involves the administration of therapeut ic radiation to malignancies during surgical procedures. IORT permits high dose delivery to tumors with the simultaneous reduction of radiation exposu re to normal tissues, which may be directly shielded or operatively mobiliz ed from the treatment volume. IORT has been investigated in various intra-a bdominal malignancies, including carcinoma of the pancreas. Techniques of I ORT were initially developed in Japan during the 1970's. Reports of therape utic benefit in some patients with unresectable pancreatic cancer encourage d further examinations by various institutions in the United States. Experi ences at the Massachusetts General Hospital in the early 1980's suggested t hat IORT enhanced survival in selected patients with locally advanced but n on-metastatic disease. However, subsequent investigations studies by a vari ety of institutions, including the Mayo Clinic, failed to establish any con clusive evidence that IORT significantly prolonged the survival enhancement of unresectable pancreatic cancer patients. A prospective multi-institutio nal study carried out by the Radiation Therapy Oncology Group (RTOG) showed an 8-month median survival, similar to conventional therapy and indicating that IORT failed to prolong survival. However, the RTOG did show that IORT rapidly and consistently palliated the severe visceral pain which often ac companied pancreatic cancer. By 1990, some institutions had explored IORT a s an adjunct to pancreatectomy, in patients with resectable tumors. Studies typically involved highly selected uncontrolled patients but did suggest t hat IORT could enhance local disease control and, in some cases, overall su rvival, when performed in conjunction with pancreatic resection. IORT appea red to be most conspicuously beneficial when used with extended radical res ections. A small prospectively randomized trial conducted at the National C ancer Institute showed significant improvement in local disease control in patients receiving IORT compared with patients receiving conventional exter nal beam postoperative radiotherapy after resection. Current evidence sugge sts that IORT may have an important palliative role in patients with unrese ctable pancreatic cancers, ameliorating visceral pain and promoting local c ontrol of the primary tumor; however, IORT appears to have no significant e ffect on overall survival. For patients with resectable disease, especially patients with locally extensive tumor, IORT appears to have benefit in enh ancing disease control and in some cases survival. It is reasonable to furt her explore the potential role of IORT in pancreatic cancer, especially as a component of multimodal therapy, since IORT's demonstrated enhancement of local control could be an important factor in eventual disease control.