Effect of tamoxifen on GH and IGF-1 serum level in stage I-II breast cancer patients

Anticancer Res. Jan-Feb 2001;21(1B):585-8.

Abstract

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.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Antineoplastic Agents, Hormonal / administration & dosage
  • Antineoplastic Agents, Hormonal / pharmacology*
  • Antineoplastic Agents, Hormonal / therapeutic use
  • Breast Neoplasms / blood
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / pathology
  • Breast Neoplasms / surgery
  • Carcinoma, Ductal, Breast / blood
  • Carcinoma, Ductal, Breast / drug therapy*
  • Carcinoma, Ductal, Breast / pathology
  • Carcinoma, Ductal, Breast / surgery
  • Chemotherapy, Adjuvant
  • Combined Modality Therapy
  • Drug Evaluation
  • Estrogen Antagonists / administration & dosage
  • Estrogen Antagonists / pharmacology*
  • Estrogen Antagonists / therapeutic use
  • Estrogens*
  • Female
  • Growth Hormone-Releasing Hormone
  • Human Growth Hormone / blood*
  • Human Growth Hormone / metabolism
  • Humans
  • Insulin-Like Growth Factor I / analysis*
  • Mastectomy, Modified Radical
  • Middle Aged
  • Neoplasm Staging
  • Neoplasms, Hormone-Dependent / blood
  • Neoplasms, Hormone-Dependent / drug therapy*
  • Neoplasms, Hormone-Dependent / pathology
  • Neoplasms, Hormone-Dependent / surgery
  • Postmenopause / blood
  • Progesterone*
  • Tamoxifen / administration & dosage
  • Tamoxifen / pharmacology*
  • Tamoxifen / therapeutic use
  • Treatment Outcome

Substances

  • Antineoplastic Agents, Hormonal
  • Estrogen Antagonists
  • Estrogens
  • Tamoxifen
  • Human Growth Hormone
  • Progesterone
  • Insulin-Like Growth Factor I
  • Growth Hormone-Releasing Hormone