The effect of tamoxifen on plasma growth hormone and prolactin in postmenopausal women with advanced breast cancer.

The effect of tamoxifen on serum levels of basal prolactin and basal and stimulated growth hormone was assessed in 10 women with advanced breast cancer prior to and after 1 and 8 weeks of treatment. Tamoxifen had no effect on basal levels of either hormone or on insulin-stimulated growth hormone. Two of 4 patients undergoing arginine provocation testing had a partial response to tamoxifen and both exhibited marked diminution of growth hormone stimulation which was not seen in the non-responders.