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 rule: sequence by mechanism and toxicity overlap, not alphabetically.

Combination Timing Comment
Chemotherapy → Endocrine Standard adjuvant for breast Cytotoxics first, then endocrine for maintenance
Endocrine → Chemotherapy Only in hormone-resistant or visceral-crisis cases  
CDK4/6 + AI/SERD Concurrent Requires CBC + LFT monitoring q 2 wk first 2 mo
mTOR (Everolimus) + AI Concurrent second-line Stomatitis common → prophylactic steroid mouthwash
PI3K (Alpelisib) + Fulvestrant Concurrent for PIK3CA-mutated ER+ disease Monitor glucose, rash
ADT + Docetaxel Concurrent in high-volume mHSPC OS gain ~ 13 mo; neutropenia risk
ADT + Abiraterone / AR antagonist Sequential or overlapping per trial Check BP, K⁺, LFTs

Never overlap two endocrine classes with the same target (e.g., AI + SERD) — no efficacy, ↑ toxicity.