A pilot study of a method of estimating the number of functional eccrine sweat glands in irradiated human skin.

Following stimulation with pilocarpine, the secretion from eccrine sweat glands produces characteristic imprints in hardening silicone polymers applied to the skin. This permits an accurate determination of the numerical density of functional eccrine glands in irradiated skin which can be compared to non-irradiated skin. A description of this inexpensive, noninvasive, and quantitative technique is presented as well as preliminary results determined in six normal subjects and 28 irradiated patients. Eleven patients, with atrophy and telangiectasia after radiotherapy to the skin to a high dose, were found to have no functional eccrine glands by this technique. A range of results from normal numbers of eccrine glands through partial and, rarely, complete loss was observed in patients given lower doses and in whom the skin was visually normal. When the irradiated side outside the boost area in 16 breast cancer patients who received postoperative radiotherapy was compared to an equivalent area on the untreated, contralateral side, 11 showed a greater than 50% reduction in the density of functional eccrine glands. The method appears to be a sensitive, quantitative assay for a permanent change in skin and so ought to facilitate meaningful comparison of different regimens of radiotherapy. Further studies are required to determine the dose-response relationship, latency and progression of the observed changes.