# Anastrozole

Source: https://onco.cc/drugs/anastrozole/  
OnCo record `anastrozole` (Treatment). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Anastrozole is a daily tablet that stops the body making oestrogen after the menopause. It treats and prevents hormone-receptor-positive breast cancer and is an alternative to tamoxifen after surgery for ductal carcinoma in situ.

## Summary

Anastrozole is a non-steroidal aromatase inhibitor developed by Zeneca (now AstraZeneca). It is taken as a 1 mg tablet once a day and is only effective after the menopause, or in premenopausal women whose ovaries have been suppressed, because it does not stop ovarian oestrogen production.

The FDA approved it in 1995 for advanced breast cancer in postmenopausal women after tamoxifen and in 2002 for adjuvant treatment of early hormone-receptor-positive disease, after the ATAC trial showed fewer recurrences than tamoxifen. In prevention, IBIS-II halved the incidence of breast cancer in high-risk postmenopausal women. After breast-conserving surgery for ductal carcinoma in situ, NSABP B-35 and IBIS-II DCIS found it at least as effective as tamoxifen, with a different side-effect profile: joint pain, bone loss and fractures rather than hot flushes, clots and endometrial cancer. Letrozole and exemestane are the other aromatase inhibitors in the class; OnCo's letrozole page covers the class as a whole.

## Fields

- Kind: Treatment
- Status: approved
- Last checked: 2026-09-17
- Also known as: ZD1033
- Tags: subtype-drugs-wave
- Brand: Arimidex
- Modality: Oral non-steroidal aromatase inhibitor
- Mechanism: Reversibly blocks aromatase (CYP19A1), the enzyme that makes oestrogen from androgens in fat, muscle and the tumour itself, cutting circulating oestrogen in postmenopausal women to near zero.
- Approvals: US 1995: Advanced breast cancer in postmenopausal women after tamoxifen; US 2002: Adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Anastrozole
- Wikipedia: https://en.wikipedia.org/wiki/Anastrozole

## Connected records

- drugs: [Exemestane](https://onco.cc/drugs/exemestane/), [Letrozole (and other aromatase inhibitors)](https://onco.cc/drugs/letrozole/), [Tamoxifen](https://onco.cc/drugs/tamoxifen/)
- cancers: [Ductal carcinoma in situ (DCIS)](https://onco.cc/cancers/ductal-carcinoma-in-situ/), [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/)
- technologies: [Endocrine therapy (SERMs, AIs, SERDs)](https://onco.cc/technologies/endocrine-therapy/)
- targets: [Aromatase (CYP19A1)](https://onco.cc/targets/aromatase/)
- companies: [AstraZeneca](https://onco.cc/companies/astrazeneca/)

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JSON: https://onco.cc/api/v1/entities/anastrozole.json