Cyclin B as a prognostic factor in low-risk node negative breast cancer

Abstract #4161 Background: The cell cycle regulation is a well-controlled mechanism in normal non-transformed cells. Cyclins are important proteins for this regulation. Cyclin B1 plays an essential role as a mitotic cyclin in the entry of mitosis from G2 phase. Previous studies have suggested that cyclin B1 over-expression could be a poor prognostic factor in breast cancer. We wanted to examine cyclin B1 as a prognostic factor in a group of patients with low-risk node negative breast cancer. Material and Methods: We compared women that died from their breast cancer (n=17) with women free from relapse > 8 years after initial diagnosis (n=24). All women had stage I, low-risk breast cancer. The groups were matched regarding tumour size, receptor status, adjuvant chemotherapy and tumor differentiation. Tumor samples were analyzed regarding cyclin B1 expression using immunohistochemistry with commercial antibodies and optical microscopy. Results: The mean percentage of cyclin B1 was significantly higher (p=0,00008) in women that died from their breast cancer (13%) compared with women free from relapse (5%). Mortality was significantly higher (p=0,001) in patients with high cyclin B (85%) than with low cyclin B (21%) using 9% as cut-off value. Conclusion: In our study, we found that low-risk node negative patients with high expression of cyclin B1 had a significantly worse outcome than patients with low expression of cyclin B1. We suggest that cyclin B1 could be a potent prognostic factor in this low-risk patient group. However, further studies are needed to confirm our findings. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 4161.