THE MODULATION OF RADIATION-INDUCED DAMAGE TO PIG SKIN BY ESSENTIAL FATTY-ACIDS

The ability of essential fatty acids (EFAS) to modulate radiation-indu ced normal tissue injury was assessed in pig skin. Female Large White pigs (approximately 25 Kg) received 3 ml/day orally of either an 'acti ve' oil [So-1100, containing 9% gamma-linolenic acid (GLA)] or a 'plac ebo' oil (So- 1 129) for just 4 weeks before or for 4 weeks before and for 16 weeks after irradiation; localised irradiation of skin was wit h single doses of beta-rays from 22.5 mm diameter Sr-90/Y-90 plaques. The severity of the acute reaction, assessed in terms of erythema or m oist desquamation, was significantly less in those pigs that received So-1100 both before and after irradiation, as compared with those rece iving that oil only prior to irradiation and the 'placebo' groups. Dos e modification factors (DMFs) of between 1.13 1.24 were obtained. A si milar reduction in the severity of acute skin injury was seen in pigs receiving So-1100 for only 10 weeks after irradiation. Late skin damag e, assessed in terms of late erythema or dermal necrosis. was also red uced with So-1100. with DMFs of 1.14 1.51. No such modification was ob served if So-1100 was only administered for 4 weeks prior to irradiati on. No adverse side-effects were apparent as a result of EFA administr ation. So-1100 may represent a safe and valuable method of increasing the therapeutic gain in radiotherapy.