Orthovoltage intraoperative radiotherapy: a new look at an old idea.

A 300 kvp orthovoltage machine has been permanently installed in an operating room for delivering intraoperative radiation therapy (IORT). A historical review of orthovoltage IORT and our present approach are described. The preliminary experience with 38 patients treated with orthovoltage IORT indicates that this technique is feasible, has low acute morbidity, and can be useful for palliation. "Radical" radiation therapy consisting of IORT "boost" treatment combined with external beam was used in 24 patients with primary or recurrent cancer. Local failure in 27 patients treated with IORT +/- external beam radiation therapy was 56%, but varied from 11% (1/9) for patients with resected disease to 78% (14/18) for patients with unresected disease. Complications occurred in nine patients (24%) and have been acceptable. There are 17 patients alive and six are NED, with follow-up of 4-18 months. There appears to be a role for orthovoltage IORT especially when combined with surgical resection for local control of advanced cancer arising in the abdomen where the use of high doses of external radiation therapy are hazardous.