| Study characteristics |
| Methods |
International phase IIIb/IV, 19 countries, multicentre, 112 sites, N = 713
Dec 1997 ‐ Nov 1999
Open, random assignation stratified by centre via predetermined randomisation list
Baseline characteristics well balanced |
| Participants |
Age range 27 ‐ 92y
Advanced or metastatic breast cancer with measurable and/or evaluable disease
Histologically/cytologically confirmed
Previous treatment with antioestrogen
WHO performance status 0‐2 |
| Interventions |
Letrozole 2.5mg versus anastrozole 1mg
Numbers in each treatment arm: 356 versus 357
Assessable patients: 299 versus 304 |
| Outcomes |
Primary ‐ TTP
Secondary‐ objective response, duration of response, rate and duration of overall clinical benefit, overall survival, general safety |
| Notes |
FU duration not reported |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
random assignation stratified by centre |
| Allocation concealment (selection bias) |
Low risk |
predetermined randomisation list |
| Blinding (performance bias and detection bias)
All outcomes |
High risk |
open‐label |
