II. Indications
-
Breast Cancer in post-menopausal women
- Estrogen Receptor positive
- Breast Cancer Prevention in pre-Menopause or post-Menopause with Breast Cancer risk >1.66% in 5 years and age over 35 years old
- Higher efficacy than Raloxifene for breast Cancer Prevention, but also higher Venous Thromboembolism and Endometrial Cancer Risks
- Unlike Tamoxifen, Raloxifene is not approved for pre-menopausal breast Cancer Prevention
III. Contraindications
- Venous Thromboembolism history
- Perioperative period
- Prolonged immobilization
- History of Cerebrovascular Accident (CVA) or Transient Ischemic Attack (TIA)
IV. Efficacy
-
Estrogen Receptor Positive Breast Cancer
- Reduces Breast Cancer recurrence (29%)
- Reduces mortality from Breast Cancer (20%)
- Reference
V. Course: Following Breast Cancer Management
- Original recommendations were for 5 year course following Breast Cancer Management
- As of 2013, ten year course is recommended following Breast Cancer Diagnosis
- One additional Breast Cancer recurrence prevented for every 27 women who extend their Tamoxifen course from 5 to 10 years
- Benefits still outweigh risks of Endometrial Cancer and Venous Thromboembolism
- Davies (2012) Lancet 10.1016/S0140-6736(12)61963-1
VI. Advantages
- Anti-Estrogen
- Reduces Breast Cancer recurrence rate
- Preserves Bone Mineral Density
- Only applies to post-menopausal patients
- Bone Mineral Density decreases if premenopausal
- Lowers Total Cholesterol and LDL Cholesterol
- Only applies to post-menopausal patients
- No effect on lipids if premenopausal
VII. Dosing
- Breast Cancer Prevention: 20 mg daily for 5 years
VIII. Adverse Effects
-
Thromboembolism
- Tamoxifen significantly increases risk
- Associated with 4 cases per 1000 women on Tamoxifen for 5 years
-
Endometrial Cancer (risks apply to postmenopausal women)
- Markedly increased risk if used more than 5 years
- Associated with 4 cases per 1000 women on Tamoxifen for 5 years
- Relative Risk for 2 to 5 years of use: 2.0
- Relative Risk for 5 or more years of use: 6.9
-
Hot Flashes
- See Hot Flashes for management
- Avoid symptomatic management with agents contraindicated following Breast Cancer
- Avoid Estrogen and Phytoestrogens
- Avoid Paroxetine and Fluoxetine (see below)
-
Cataracts
- Eye Exam every 1-2 years
IX. Drug Interactions
-
CYP2D6 Inhibitors (e.g. Paroxetine, Fluoxetine, Bupropion)
- May decrease Tamoxifen efficacy (avoid these CYP2D6 Inhibitors in Breast Cancer patients)
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Related Studies
tamoxifen (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
TAMOXIFEN 10 MG TABLET | Generic | $0.18 each |
TAMOXIFEN 20 MG TABLET | Generic | $0.33 each |