Randomised trial of letrozole plus usual care versus usual care without letrozole to prevent new breast cancer events in postmenopausal women who have completed a minimum of 4 years of adjuvant endocrine therapy for early, hormone responsive breast cancer more than 1 year previous, and who are disease-free at trial entry (ANZ 0501 LATER)

* Dataset for 360 post-menopausal patients with previously resected ER and/or PR positive invasive breast cancer, currently breast cancer free * Previous treatment with adjuvant endocrine therapy * Randomisation: 179 women to the observation group (no further drug treatment) and 181 women to the letrozole group (2.5mg letrozole daily for 5 years) * Disease-free and overall survival data until 10 years after randomisation * Regional and distant recurrence data until 10 years after randomisation * Symptoms/toxicities/Illnesses, bone fractures until 10 years after randomisation * Drug compliance until 5 years after randomisation * LATER tested a new strategy to prevent disease recurrence and death due to breast cancer. The purpose of the study was to find out whether later re-treatment of participants with adjuvant letrozole therapy can prevent or delay new breast cancers from reoccurring in postmenopausal women previously treated with adjuvant endocrine therapy.