Sweat gland function as a measure of radiation change

Background: Radiotherapy may result in dryness of the skin even when no oth er change can be detected. We describe a system for recording the electrica l conductance of skin as a measure of sweat gland function. Patients and methods: In 22 normal volunteers close agreement was obtained between measurements obtained from comparable sites on both sides of the ch est. Measurements were subsequently made in 38 patients treated by radiothe rapy to one side of the chest for rumours of the breast or lung using one o f five different fractionation schedules. Simultaneous readings were obtain ed from both sides of the chest with the Iron irradiated side acting as a c ontrol. Results: A dose response relationship was demonstrated: five patients who r eceived the equivalent total dose of 15 Gy in 2-Gy fractions showed no chan ge in conductance. Sixteen out of 23 who received an equivalent total dose of 42-46 Gy in 2-Gy fractions had a greater than 22% reduction in mean skin conductance compared with that of the control areas despite the skin appea ring normal in the large majority. Marked changes in skin conductance were seen after higher total doses. In a prospective study IS women receiving br east irradiation underwent weekly readings during treatment. A mean reducti on of 40% in skin conductance was noted by the end of the second week of tr eatment prior to any clinical evidence of radiation change. Skin conductanc e returned to normal in 44% of patients by 6 months. In the remainder, thos e patients who showed the greatest reduction in skin conductance during tre atment demonstrated the least recovery. Conclusions: Changes in sweat gland function can be detected and quantified in skin which map otherwise appear normal. Differences may so be demonstra ted between areas treated using different fractionation schedules and the m ethod may be applied to the defection during radiotherapy of unusually sens itive patient (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.