• The quality of life of patients treated with exemestane to that of patients treated with tamoxifen [ Time Frame: Every 3 months during first year then every 6 months for 4 years ] [ Designated as safety issue: No ]
• Overall survival between the 2 treatment groups [ Time Frame: Every 3 months during first year then every 6 months for 4 years ] [ Designated as safety issue: Yes ]
• incidence of a second breast cancer (contralateral) between the 2 treatment groups [ Time Frame: Every 3 months during first year then every 6 months for 4 years ] [ Designated as safety issue: Yes ]
• General tolerance in the short- and long-term between the 2 treatment groups [ Time Frame: Every 3 months during first year then every 6 months dor 4 years ] [ Designated as safety issue: Yes ]

• To compare the following between the 2 treatment groups:
• -Overall survival.
• -The incidence of a second breast cancer (contralateral).
• -General tolerance in the short- and long-term.

To compare recurrence free survival between two treatment groups (5 years with exemestane vs 2.5 to 3 years tamoxifen followed by 2 to 2.5 years of exemestane for a total duration of 5 years)

This Pfizer sponsored trial is part of an international collaboration of investigators conducting 7 similar yet independent studies in 9 countries. This study is designed to be part of the larger TEAM trial where the data from these 7 studies will be combined. A pre-specified analysis of the pooled data will be conducted.

• Drug: exemestane
• Drug: tamoxifen

Inclusion Criteria:

• HR+ post-menopausal patients with non-metastatic breast cancer

Exclusion Criteria:

• Any of the following: HR-, non-menopausal patient, metastatic breast cancer