Serum amylase as a measure of salivary gland radiation damage

Abstract

Post-radiation changes in serum amylase in the blood of patients treated with 4 MV X rays in hyperbaric oxygen have been studied during courses of weekly fractionated treatment for advanced head and neck cancer. The data confirm the results of Kashima et al. (1965) that hyperamylasaemia results from irradiation of salivary tissues and is a sensitive, and quantitative, be it indirect, index of damage to this tissue. During fractionated therapy using 600–725 rad fractions at weekly intervals, the hyperamylasaemic response decreased rapidly in intensity, and it is concluded from the data obtained that three to four such fractions destroy most of the amylase-secreting salivary tissue exposed to this dosage, thus greatly reducing or preventing a further hyperamylasaemic response when the tissues are re-exposed to irradiation. On the assumption that this rapid cell death of differentiated non-dividing secretory cells might result from changes in cell permeability, and more particularly from a labilisation of lysosomal membranes, and result in the release of acid hydrolases and autocytolysis, the effects of administering large doses of stabilising or labilising steroids before and after irradiation were examined. Prednisolone possibly protected against salivary gland damage, but the effects observed may have been due to attenuation of the hyperamylasaemic response and rate of cell death. Medroxyprogesterone did not appear to modify radiosensitivity. Sialagogues admininistered before irradiation to promote secretion had no apparent effect on subsequent serum amylase levels, nor did stellate ganglion block performed before irradiation.