BACKGROUND: The majority of breast cancer patients are postmenopausal women who 
are increasingly being offered adjuvant chemotherapy. Since the beneficial 
effect of chemotherapy in postmenopausal patients predominantly occurs in the 
first 5 years after diagnosis, a prognostic marker for early events can be of 
use for adjuvant treatment decision making. The aim of this study was to 
evaluate the prognostic value of the 70-gene prognosis signature for early 
events in postmenopausal patients.
METHODS: Frozen tumor samples from 148 patients aged 55-70 years were selected 
(T1-2, N0) and classified by the 70-gene prognosis signature (MammaPrint) into 
good or poor prognosis. Eighteen percent received hormonal therapy.
RESULTS: Breast cancer-specific survival (BCSS) at 5 years was 99% for the 
good-prognosis signature versus 80% for the poor-prognosis signature group (P = 
0.036). The 70-gene prognosis signature was a significant and independent 
predictor of BCCS during the first 5 years of follow-up with an adjusted hazard 
ratio of 14.4 (95% confidence interval 1.7-122.2; P = 0.01) at 5 years.
CONCLUSION: The 70-gene prognosis signature can accurately select postmenopausal 
patients at low risk of breast cancer-related death within 5 years of diagnosis 
and can be of clinical use in selecting postmenopausal women for adjuvant 
chemotherapy.