Aromatase inhibitors versus tamoxifen in early breast cancer: patient-level meta-analysis of the randomised trials
- Study type
- Meta-analysis
- Study name
- EBCTCG
- Design
- Patient-level (individual) meta-analysis of randomised trials
- Sample size
- 31,920 postmenopausal women
- Source
- The Lancet · 2015
In plain words
This study brought together information on more than 31 thousand postmenopausal women with oestrogen receptor-positive early breast cancer from different trials and compared aromatase inhibitor drugs with tamoxifen. The results showed that aromatase inhibitors lower the chance of the cancer coming back by about 30% compared with tamoxifen during the time the two treatments differ, and that 5 years of them lowers deaths from breast cancer at 10 years by about 15% compared with 5 years of tamoxifen. Aromatase inhibitors caused less cancer of the womb (endometrial cancer) but more bone fractures than tamoxifen. Discuss the right treatment choice with your treating doctor.
Key results
Treatment arms and regimens
5 years of an aromatase inhibitor versus 5 years of tamoxifen.
Meta-analysis of multiple trials; dose and schedule varied between trials and no single dose is reported.
5 years of an aromatase inhibitor versus 2 to 3 years of tamoxifen then switching to an aromatase inhibitor to year 5.
2 to 3 years of tamoxifen then an aromatase inhibitor to year 5 versus 5 years of tamoxifen.
Source of the regimen details: Abstract of the paper (meta-analysis; treatment durations reported, no single dose)
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 oestrogen receptor-positive early breast cancer who took part in randomised trials comparing an aromatase inhibitor with tamoxifen.
Endpoints
Main endpoints: any breast cancer recurrence, breast cancer mortality, death without recurrence and all-cause mortality. Analyses were by intention to treat, with log-rank tests stratified by age, nodal status and trial, yielding first-event rate ratios (RR) for aromatase inhibitor versus tamoxifen.
Safety and side effects
Endometrial cancer was less frequent with aromatase inhibitors than with tamoxifen (10-year incidence 0.4% versus 1.2%; RR 0.33; 95% CI 0.21–0.51). In contrast, bone fractures were more frequent with aromatase inhibitors (5-year risk 8.2% versus 5.5%; RR 1.42; 95% CI 1.28–1.57). Non-breast-cancer mortality was similar in the two groups.
Clinical significance and place in guidelines
This meta-analysis shows that in postmenopausal women with oestrogen receptor-positive early breast cancer, use of an aromatase inhibitor (either for the full 5 years or switching to it after 2 to 3 years of tamoxifen) reduces recurrence and breast cancer mortality compared with 5 years of tamoxifen alone. The observed benefit depended little on age, body mass index, stage, grade or progesterone receptor or HER2 status. In decision-making, the reduction in endometrial cancer should be weighed against the increase in bone fractures. The place of these findings in current clinical guidelines should be checked separately.
Limitations
The abstract reports only pooled findings; details of each trial, the specific drugs and the doses are in the full text. The study population was limited to postmenopausal women with oestrogen receptor-positive early breast cancer. In the comparisons examined after the period of treatment difference, the reduction in recurrence was not statistically significant.
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.