METHODOLOGICAL APPROACHES AND POSTOPERATI VE MORBIDITY OF INTRAOPERATIVE RADIOTHERAPY FOR SOFT-TISSUE SARCOMAS

Since June 1991 the IORT facility has operated a dedicated linear acce lerator, which was installed within the central operating theater of t he Department of Surgery. As of 9/92 a total of 28 patients suffering from peripheral (n = 20) or centrally (n = 8) located soft tissue sarc omas had been were treated. Thirteen patients revealed a primary and 1 5 patients a recurrent tumor. Tumor resection with negative margins wa s performed in 20 patients, positive margins remained in 5 patients, a nd gross macroscopic residual disease in 3 patients. Combined intraope rative and external beam radiotherapy was applied in 22 patients, usin g IORT doses of 10-20 Gy and an external beam dose of 26-50 Gy. Three patients were irradiated intraoperatively twice with a time interval o f 24 h. After a median follow-up of 9.9 months, 20 patients are diseas e free. Two patients died 4 and 5 months after the end of therapy with rapidly progressive distant metastases. An in-field failure within th e external beam target volume was seen in 1 patient and local failure at the field margin of the external field in 3 patients. So far, there have been no IORT infield failures. Follow-up is performed with magne tic resonance imaging. In 3 patients a second operation was necessary because of a severe wound infection, including one patient suffering f rom osteomyelitis of a neighboring bone. Mild sensory neuropathy occur red in 1 patient 7 months after treatment. Overall only mild and rever sible postoperative and posttherapeutic complications were seen. Based on the retrospective analysis of the target volumes chosen during thi s working period, a set of horse-shoe-shaped cones was designed, which permitted circular and longitudinal target volumes with a homogeneous doses to be delivered as well. With this dedicated IORT facility simp le and safe application of a high boost dose is possible. To improve l ocal tumor control in soft tissue sarcomas further, a clear definition of the target volume, followed by an exact verification and at least integration of this target volume in a three-dimensional treatment pla n, is necessary.