Cyclin E expression in operable breast cancer quantified using real-time RT-PCR: a comparative study with immunostaining.

Objective: The main purpose of this retrospective study was to compare cyclin E expression levels in operable breast cancer patients determined using real-time RT-PCR and immunostaining. The prognostic relevance of cyclin E was also investigated.

Methods: Specimens of invasive ductal breast cancer tissues obtained from 124 women during radical mastectomy were analyzed.

Results: Of the tumor samples, 40.3 and 59.7% showed high expression of cyclin E in RT-PCR and immunostaining, respectively. The overall agreement probability was 0.032 according to Scott's pi statistic. With a median follow-up of 55.5 months, cyclin E expression assessed using immunostaining was an independent negative prognostic factor in the node positive group (hazard ratio 3.1; 95% CI 1.0-9.2; P = 0.045). Cyclin E expression correlated with absence of steroid receptors and younger age. RT-PCR results did not predict survival in any group of patients.

Conclusions: Disagreement between real-time RT-PCR and immunostaining was demonstrated. Immunostaining seems to be the more reliable method for assessing cyclin E in breast cancer cells.