ATAC - Endometrial Sub-Protocol

A Randomised, Double Blind Trial to Assess the Incidence of Endometrial Changes With Arimidex Alone, Nolvadex Alone, or Arimidex and Nolvadex in Combination, When Used as Adjuvant Treatment for Breast Cancer in Postmenopausal Women

Status

Completed

Phases

Phase 3

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT00814125

Enrollment

285

Registered

2008-12-24

Start date

1997-06-30

Completion date

2005-12-31

Last updated

2009-05-01

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Breast Cancer

Keywords

Endometrial, Endometrial histological findings

Brief summary

To compare the difference between the ARIMIDEX group and the tamoxifen group in the incidence of abnormal endometrial histological findings arising after treatment has commenced.

Interventions

DRUGAnastrozole (Arimidex)

1mg, orally, once daily

DRUGTamoxifen (Nolvadex)

20mg, orally, once daily

DRUGNolvadex placebo

DRUGArimidex placebo

Study design

Allocation

RANDOMIZED

Intervention model

PARALLEL

Masking

DOUBLE (Subject, Investigator)

Eligibility

Sex/Gender

FEMALE

Age

45 Years to No maximum

Healthy volunteers

Inclusion criteria

* Patients eligible for entry into the main ATAC trial (1033IL/0029) * Not received any previous tamoxifen, for whatever reason * Not undergone a hysterectomy and do not have a hysterectomy planned within the next 6 years * No previous endometrial ablation

Exclusion criteria

* Excluded from entry into the main ATAC trial (1033IL/0029). As detailed in Section 4.4 of the main ATAC trial (1033IL/0029)

Design outcomes

Primary

Measure	Time frame
Withdrawl	—
Death	—

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026