[Serum estrone sulfate levels in patients with breast cancer]

Estrone and estradiol-17 beta concentration in breast cancer tissue are reported to be an order of magnitude higher than those of circulating plasma in breast cancer patients. This high level of estrogen is provided by local production from estrone sulfate (E1-S) through the sulfatase pathway. Then serum E1-S level was determined using direct radioimmunoassay method in order to monitor the estrogen kinetics of post-operative breast cancer patients. Peri-operative sequential E1-S determination was carried out in 10 patients. Among them, extremely higher level, as compared with normal menstruating level of 625-2670pg/ml, was observed just after an administration of tamoxifen (three weeks after operation) in two of 5 pre-menopausal patients. In order to evaluate the effect of tamoxifen on serum level of E1-S in post-operative pre-menopausal patients, serum E1-S level in 42 post-operative outpatients was examined. Although there was no difference in the average level of E1-S in post-menopausal patients treated with or without tamoxifen, average E1-S level in pre-menopausal patients treated with tamoxifen as adjuvant therapy was significantly higher than that in patients without tamoxifen. These results suggests that the administration of tamoxifen to premenopausal patients should be reconsidered from a view point of the estrogen kinetics.