AlternativeArimidex / Femara / Aromasin
Aromatase inhibitors (anastrozole, letrozole, exemestane)
Aromatase inhibitors (postmenopausal ER+ breast cancer)
First-line adjuvant in postmenopausal ER+ breast cancer.
Oral
First-line for
- Adjuvant postmenopausal ER+ breast cancer
- Premenopausal (with ovarian suppression) in high-risk disease
Mechanism
Block peripheral conversion of androgens to oestrogens → profound oestrogen suppression (ineffective if functioning ovaries).
"AI = bone & joints"
- Arthralgia in ~ 30%
- Osteoporosis — DEXA
- Only works if postmenopausal (or on GnRHa)
Dosing
- Anastrozole
- 1 mg PO OD
- Letrozole
- 2.5 mg PO OD
- Exemestane
- 25 mg PO OD
Contraindications
- AbsolutePremenopausal without ovarian suppression, pregnancy, breastfeeding
Side effects
- Arthralgia / stiffness
- Osteoporosis / fracture
- Hot flushes
- Vaginal dryness / dyspareunia
Fetal & maternal notes
- • Teratogenic — contraception required
Key interactions
Tamoxifen
AvoidAntagonistic — do not combine
HRT
AvoidAbsolutely contraindicated
Clinical pearls
- 💡 Baseline + biennial DEXA; bisphosphonate if osteoporotic
- 💡 Local vaginal oestrogen may be considered on specialist advice for GSM
Content last reviewed: REPLACE_ME (e.g. 2026-07)
Spotted something out of date? See our disclaimer or use Report an Error above.