This study was performed to investigate whether the E2F1 protein expression can be used as a prognostic factor in clinical breast cancer.

The expressions of E2F1 and retinoblastoma protein (pRB) were analyzed in 165 lymph node positive breast cancers. All patients underwent adjuvant chemotherapy with fluorouracil, doxorubicin, and cyclophosphamide (FAC) after curative surgery.

E2F1 was expressed in 43.6% and pRB was expressed in 46.1%. E2F1 expression was significantly increased in pRB-expressing tumors and was associated with S-phase fraction. By univariate survival analyses, E2F1 expression and ER were the significant prognostic factors for the disease recurrence and patient survival. E2F1 was the only significant prognostic factor for the patient outcome after FAC chemotherapy by multivariate analysis.

The results of the current study indicate that abnormal expression of E2F1 and pRB is prevalent and are intimately associated with each other in clinical breast cancer. A significant association between E2F1 expression and patient survival after FAC chemotherapy mondates a further validation study.