Statement: the primary trial and the secondary trial use ECOG to evaluate potential candidates' performance status.
Primary_evidence: Inclusion Criteria:   Pre-menopausal women aged 18 years or over with histologically/cytologically-confirmed oestrogen receptor positive (ER +ve) breast cancer   World Health Organization (WHO) performance status of 0, 1, or 2   Provided written informed consent Exclusion Criteria:   Treatment with tamoxifen or other hormonal therapies as early breast cancer (EBC) adjuvant in the previous 24 weeks   Received radiotherapy within the past 4 weeks   History of systemic malignancy other than breast cancer within the previous 3 years   Estimated survival less than 24 weeks
Secondary_evidence: Inclusion Criteria:   Recurrent or residual metastatic breast carcinoma   Zubrod performance status less than 2   18-60 years old   Related donor human leukocyte antigen (HLA)-compatible for allogeneic transplantation or unrelated HLA-compatible donor.   No major organ dysfunction or active infection Exclusion Criteria: None