THEORETICAL AND PRACTICAL USES OF ELECTIVE SYSTEMIC (HALF-BODY) IRRADIATION AFTER 20 YEARS OF EXPERIMENTAL-DESIGNS

This article traces the concept and different uses of systemic (Half-B ody) irradiation (HBI) for the last 20 years, It presents both indirec t and direct evidence of HBI effectiveness and discusses the various h ypothesis that have been advanced to explain its success as a palliati ve and more recently as an elective therapeutic tool, The article disc usses the transition from treating overt to subclinical metastatic dis ease and recalls the pioneer uses of elective HBI in lung and prostate cancers. Recent uses of elective HBI with a variety of unconventional fractionation schemes are discussed, These include clinical trials (5 1 patients with lung, esophagus, colorectal, prostate, ovary and endom etrial cancers) and animal experiments (1195 C3H mice), An intriguing combination of hyper/hypo fractionated HBI proved to be the less toxic of all the schedules used in animals where mortality data, analyzed b y the LQ Model, yielded an alpha/beta ratio of 8.3 Gy, a value general ly associated with acutely responding tissue. (C) 1997 Elsevier Scienc e Inc.