A Comparison of Letrozole and Tamoxifen in Postmenopausal Women with Early Breast Cancer
- Study type
- Clinical trial
- Study name
- BIG 1-98
- Phase
- Phase 3
- Design
- Double-blind randomised phase 3 trial
- Sample size
- 8010 patients (4003 in the letrozole group and 4007 in the tamoxifen group)
- Source
- N Engl J Med · 2005
- Trial registration
- NCT00004205
In plain words
In this large study, two hormone drugs, letrozole and tamoxifen, were compared in postmenopausal women with hormone-sensitive breast cancer. Letrozole lowered the risk of the cancer coming back, especially in distant organs, more than tamoxifen did. The two drugs had different side effects: blood clots, cancer of the womb and vaginal bleeding were more common with tamoxifen, while bone and heart problems and high blood cholesterol were more common with letrozole. The drug should be chosen with your own doctor, based on each patient's situation.
Key results
Treatment arms and regimens
Groups assigned to receive letrozole first (letrozole alone and letrozole followed by tamoxifen; events and follow-up in the sequential groups were included up to the time of switching therapy). The total duration of treatment in the trial was five years.
Letrozole 2.5 mg orally daily for 5 years (or, in the sequential group, letrozole for 2 years followed by tamoxifen for 3 years).
Groups assigned to receive tamoxifen first (tamoxifen alone and tamoxifen followed by letrozole; events and follow-up in the sequential groups were included up to the time of switching therapy). The total duration of treatment in the trial was five years.
Tamoxifen 20 mg orally daily for 5 years (or, in the sequential group, tamoxifen for 2 years followed by letrozole for 3 years).
Source of the regimen details: ClinicalTrials.gov NCT00004205
Doses are given for the information of specialists, as in this study’s protocol, and are not a prescription. Every drug must be prescribed by the treating physician for the individual patient.
Study population
Postmenopausal women with hormone receptor-positive (steroid hormone receptor-positive) breast cancer receiving adjuvant therapy. This analysis included 8010 women with assessable data.
Endpoints
The abstract does not explicitly state the primary endpoint; the reported outcomes include disease-free survival, risk of distant recurrence and adverse events.
Safety and side effects
Thromboembolism, endometrial cancer and vaginal bleeding were more common in the tamoxifen group. Women who received letrozole had more skeletal and cardiac events and hypercholesterolaemia. Rates of grade 3 or higher adverse events are not reported in the abstract.
Clinical significance and place in guidelines
Based on this abstract, letrozole showed better disease-free survival than tamoxifen as adjuvant therapy in postmenopausal women with hormone receptor-positive breast cancer, particularly through a reduction in distant recurrence. The different adverse-event profiles of the two drugs (skeletal and cardiac events and lipids with letrozole; thromboembolism and endometrial effects with tamoxifen) must also be weighed when choosing treatment. The current place of this approach in clinical guidelines should be checked separately.
Limitations
This analysis was done at a short median follow-up (25.8 months), so long-term outcomes and late adverse events were not assessed. The sequential-treatment groups were analysed only up to the time of switching therapy. Other limitations should be taken from the full paper.
This summary was prepared by the editorial team from the published paper; the original paper is the final reference. Read the original abstract on PubMed.