Surgical approaches and techniques in intraoperative radiotherapy for intra-abdominal, retroperitoneal, and pelvic neoplasms.

Eighty-five patients with locally advanced intra-abdominal, retroperitoneal, and pelvic malignant diseases have been treated at the National Cancer Institute (NCI) with electron beam intraoperative radiotherapy (IORT). In general, IORT was performed after resection to the tumor bed and to areas of locoregional spread. IORT was delivered directly to some unresectable tumors. The median survival for the entire NCI patient group was 13.9 months, with 34% of the patients projected to achieve local control of disease at 5 years. Multiple abutting IORT fields were used in 76% of the patients; they encompassed treatment areas as large as 569 cm2 and involved as many as five separate IORT applications. Multiple fields were matched along straight edges on the treatment applicators or provided by means of lead shielding strips. Areas of field overlap were prevented by the use of lead shields. Surgical approaches and radiotherapeutic techniques of multiple field matching have been developed and are detailed for carcinoma of the pancreas, carcinoma of the stomach, sarcomas of the retroperitoneum, carcinoma of the rectum, and tumors of the pelvic girdle.