Experimental and clinical studies with intraoperative radiotherapy

Area of Science:

• Radiation Oncology
• Surgical Oncology
• Experimental Oncology

Background:

• Intraoperative radiotherapy (IORT) is an advanced treatment modality.
• Understanding normal tissue tolerance is crucial for optimizing IORT protocols.
• Evaluating IORT's efficacy in advanced cancers is essential.

Purpose of the Study:

• To determine the tolerance of normal tissues to intraoperative electron beam irradiation.
• To assess the feasibility and outcomes of combining IORT with radical surgery for advanced malignancies.

Main Methods:

• Dose-ranging studies in 65 dogs to evaluate tolerance of aorta, vena cava, ureters, arterial anastomoses, intestinal suture lines, and bile ducts to electron irradiation.
• A clinical trial involving 20 patients with advanced tumors (stomach, pancreas, liver hilus, retroperitoneal sarcomas, pelvic osteosarcomas) undergoing tumor resection followed by IORT.
• Some patients received additional postoperative external beam radiotherapy.

Main Results:

• In dogs, intact aorta and vena cava tolerated up to 5,000 rads. Ureteral and bile duct stenosis occurred at 3,000 and 2,000 rads, respectively. Intestinal and arterial anastomoses healed after 4,500 rads, though occlusion risk existed. Biliary-enteric anastomoses failed healing.
• In the clinical trial, treatment mortality was 4/20. Morbidity occurred in 4/16 survivors. Local tumor control was achieved in 11/16 patients with a median follow-up of 18 months.
• IORT combined with surgery demonstrated feasibility and potentially improved local tumor control.

Conclusions:

• Intraoperative radiotherapy is a viable addition to surgical resection for locally advanced tumors.
• The associated mortality and morbidity appear comparable to surgery alone.
• IORT may enhance local tumor control rates in challenging oncological cases.