Aims: CCND1 and EMSY, on 11q13, are frequently amplified in breast cancer. CCND1 is implicated in cell cycle progression and EMSY is a BRCA2-associated repressor protein. The aim was to investigate gene copy numbers of CCND1 and EMSY and to determine if CCND1 amplification is associated with reduced survival of tamoxifen-treated breast cancer patients.
Methods and results: Fluorescence in situ hybridization (FISH) was performed on 111 consecutive and 354 oestrogen receptor (ER)+ tamoxifen-treated breast cancers. In the consecutive set, CCND1 and EMSY were amplified in 14.8% and 7.2%, respectively, and deleted in 8.7% and 13.5%, respectively. In the ER+ set, CCND1 and EMSY were amplified in 20.6% and 9.6%, respectively, and deleted in 1.7% and 4.2%, respectively. CCND1 and EMSY gene amplifications were associated with decreased overall survival (OS) (P = 0.03 and P = 0.04, respectively) of patients in the ER+ set.
Conclusion: As hypothesized, CCND1 amplifications are associated with poor OS in ER+ patients. EMSY amplification is also associated with poor OS. However, as >70% of EMSY amplifications were CCND1 amplified, EMSY may not have any additional effect on survival of ER+ breast cancer.