Particle radiation therapy: experimental basis and clinical application.

Conventional radiation therapy can eradicate cancers within tissues of their origin and regional spread with conservation of anatomic structure, thus preserving function and cosmesis. New treatment methods may improve the therapeutic ratio either by increasing the frequency of tumor control or lessening the treatment-related morbidity, or both. There are several physical and biological reasons why particle radiation therapy may increase tumor cell killing without increasing normal tissue sequelae. After preliminary basic research, clinical trials of fast neutron and proton teletherapy were started. Over 700 patients were treated with fast neutron beams in 3 U.S. research programs. These studies will be extended to include negative pi mesons and heavy particles.