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Study on the Effects of Tamoxifen on GH and IGF-1 Levels
Effect of tamoxifen on GH and IGF-1 serum level in stage I-II breast cancer patients.
Mandala M, Moro C, Ferretti G, Calabro MG, Nole F, Rocca A, Munzone E, Castro A, Curigliano G.
Division of Medical Oncology, European Institute of Oncology, Via Ripamonti 435, 20141-Milan, Italy. mario.mandala@ieo.it
OBJECTIVE: Tamoxifen suppresses insulin-like growth factor-1 (IGF-1) plasma levels in early and advanced breast cancer patients. Relationships between tamoxifen (GH) and IGF-1 are complex and not completely described yet. The present investigation was performed to evaluate the effect of acute and chronic tamoxifen administration on GH response to growth hormone-releasing hormone (GHRH), as well as on IGF-1 serum levels. MATERIALS AND METHODS: Evaluation of GH after administration of GHRH was performed (a) at baseline, (b) 3 hours after 20 mg oral administration of tamoxifen and (c) after 12 weeks of 20 mg a day oral tamoxifen treatment, in fifteen postmenopausal stage I-II breast cancer patients. IGF-I was measured at baseline and after chronic tamoxifen administration. RESULTS: The GH response to GHRH was significantly reduced after 12 weeks of tamoxifen 10 mg administered twice a day orally (mean peak 3.2 +/- 0.2 micrograms/l, mean AUC 261.3 +/- 18.2 micrograms/minute p < 0.01 versus basal AUC). A concomitant significant reduction of IGF-1 was observed after 3 months of tamoxifen treatment. Basal pretreatment levels of 113.2 +/- 15.5 micrograms/l were suppressed to 70 +/- 7.9 micrograms/l (p < 0.01). CONCLUSION: Our study confirm the inhibitory effect of tamoxifen on IGF-I and suggested, as shown in previous in vitro data, that its suppression could be directly related to GH reduction in response to GHRH stimulation.
Effect of tamoxifen on GH and IGF-1 serum level in stage I-II breast cancer patients.
Mandala M, Moro C, Ferretti G, Calabro MG, Nole F, Rocca A, Munzone E, Castro A, Curigliano G.
Division of Medical Oncology, European Institute of Oncology, Via Ripamonti 435, 20141-Milan, Italy. mario.mandala@ieo.it
OBJECTIVE: Tamoxifen suppresses insulin-like growth factor-1 (IGF-1) plasma levels in early and advanced breast cancer patients. Relationships between tamoxifen (GH) and IGF-1 are complex and not completely described yet. The present investigation was performed to evaluate the effect of acute and chronic tamoxifen administration on GH response to growth hormone-releasing hormone (GHRH), as well as on IGF-1 serum levels. MATERIALS AND METHODS: Evaluation of GH after administration of GHRH was performed (a) at baseline, (b) 3 hours after 20 mg oral administration of tamoxifen and (c) after 12 weeks of 20 mg a day oral tamoxifen treatment, in fifteen postmenopausal stage I-II breast cancer patients. IGF-I was measured at baseline and after chronic tamoxifen administration. RESULTS: The GH response to GHRH was significantly reduced after 12 weeks of tamoxifen 10 mg administered twice a day orally (mean peak 3.2 +/- 0.2 micrograms/l, mean AUC 261.3 +/- 18.2 micrograms/minute p < 0.01 versus basal AUC). A concomitant significant reduction of IGF-1 was observed after 3 months of tamoxifen treatment. Basal pretreatment levels of 113.2 +/- 15.5 micrograms/l were suppressed to 70 +/- 7.9 micrograms/l (p < 0.01). CONCLUSION: Our study confirm the inhibitory effect of tamoxifen on IGF-I and suggested, as shown in previous in vitro data, that its suppression could be directly related to GH reduction in response to GHRH stimulation.
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