Course Content
Module 1 — Principles of Hormone Therapy in Oncology
Mechanism and Dosing Overview Aromatase Inhibitors (AIs): block the enzyme aromatase (CYP19A1), which converts androgens to estrogens in adipose and peripheral tissues. Examples: Anastrozole 1 mg orally daily, Letrozole 2.5 mg orally daily, Exemestane 25 mg orally daily. These are the preferred agents in postmenopausal women with estrogen receptor–positive breast cancer. Selective Estrogen Receptor Modulators (SERMs): such as Tamoxifen 20 mg orally daily — bind the estrogen receptor and act as antagonists in breast tissue but partial agonists in bone and endometrium. Selective Estrogen Receptor Degraders (SERDs): such as Fulvestrant 500 mg intramuscularly on days 0, 14, 28, then every 28 days thereafter — promote estrogen receptor degradation. CYP17 Inhibitors: Abiraterone acetate 1000 mg orally daily on an empty stomach plus Prednisone 5 mg orally twice daily — block the CYP17A1 enzyme, suppressing androgen synthesis in adrenal glands and tumors. Gonadotropin-Releasing Hormone (GnRH) Agonists and Antagonists: Leuprolide 7.5 mg subcutaneously every 4 weeks or depot every 3–6 months; Degarelix 240 mg subcutaneously loading dose, then 80 mg every 4 weeks; Relugolix 120 mg orally daily — suppress testosterone or estrogen production by downregulating or directly blocking pituitary gonadotropin release.
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Hormone Therapy for Cancer Patients: Mechanisms, Indications, and Clinical Practice

Core message:
Hormone therapy doesn’t just palliate; it changes natural history when used correctly and long enough.
(EBCTCG 2023; NCCN 2025)

Setting Typical survival gain Notes
ER + Breast (AI vs Tamoxifen) ~30 % ↓ recurrence / ~15 % ↓ mortality 5 y AI > 5 y Tamoxifen
Breast, extended AI 10 y Additional ~3–5 % DFS benefit Bone loss doubles
Locally advanced Prostate (ADT + RT vs RT alone) ~20 % ↑ 15-y OS Max benefit with 24–36 mo ADT
Metastatic Prostate (ADT + AR blocker) +12–24 mo median OS Largest modern improvement

Predictors of benefit

  • Receptor expression level (>10 % cells = best).

  • Early PSA/estradiol nadir.

  • Longer time to biochemical relapse.

  • Absence of visceral metastases.