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.
Cancer 40:481-483, 1977
H E ULTIMATE OBJECTIVE OF RESEARCH IN
T radiation therapy is the improvement of the therapeutic ratio within the irradiated volume. This can be accomplished either by increasing tumor cell killing or decreasing sequelae in normal tissues, or both. T h e result is more frequent local and regional tumor control, which can be curative, and better preservation of anatomic structure with retention of function and cosmesis. More effective local/regional treatment, particularly when combined with effective systemic treatment, i.e. chemotherapy and/or immunotherapy, can be an important contributor to improved management of patients with a spectrum of cancers, whether this be measured by cure, long-term tumor control or palliation.
Physical a n d Biological Basis
So-called heavy particles, whether uncharged (neutrons) or charged (protons), helium ions, negative pi mesons and heavy ions, are of interest because of physical and biological differences compared to x-ray or gamma photons.