[Pion therapy at SIN--7 years' experience].

At SIN (Swiss Institute for Nuclear Research) cancer treatment with negatively charged pi-mesons was initiated in 1980, and 331 patients have been treated by the end of 1987. Patients were treated in a individually-made cylindrical couch with three dimensionally optimized dynamic tumor-conforming technique (spot scanning technique). Especially for retroperitoneal and pelvic soft tissue sarcomas pions seem to be promising with 3-year local control rate 94 percent and 3-year survival rate 70 percent (15 patient, 17 manifestations). And also prostate cancers seem to be well controlled by pions without any severe complications. From these results at least for these tumors it seems worthwhile to conduct phase III prospective trials.