Global collaboration

Since the 1940s hundreds of randomised trials involving hundreds of thousands of women have assessed the long-term benefits and side-effects of different treatment options for early breast cancer, and many trials are still being undertaken. Since 1983, the EBCTCG has been bringing together and analysing the evidence on the major questions with emphasis on evidence from large-scale randomisation and long-term follow-up.

The EBCTCG involves almost all trialists worldwide who have done relevant randomised trials of the treatment of breast cancer. Trialists are periodically invited to send data on each woman who participated in their study to the EBCTCG Secretariat.

Several hundred research groups have shared individual patient data on over 700,000 women in 650 randomised trials. The EBCTCG meta-analyses have produced definitive estimates of the effects of various treatments on time to recurrence, breast cancer death, second cancers and death from other causes. These treatments include various types of surgery, radiotherapy, chemotherapy, endocrine therapy, biological therapies, and other agents such as bisphosphonates. Reviews on the trials of mammographic screening are also under way.

The large EBCTCG datasets allow the most reliable exploration of any differences in the effects of the treatments in particular subgroups of women, or between treatments within the same class e.g different types of chemotherapy, or different types of endocrine therapy. The prognostic importance of baseline characteristics, such as the impact of various tumour characteristics and body-mass index on risk of recurrence, can also be investigated.