Background: Proliferative markers are not recommended as prognostic factors for clinical use in breast cancer due to lack of standardization in methodology. However, proliferation is driving several gene expression signatures emphasizing the need for a reliable proliferative marker for clinical use. Studies suggest that cyclin A is a prognostic marker with satisfying reproducibility. We investigated cyclin A as a prognostic marker in node-negative breast cancer using previously defined cutoff values.
Patients and methods: In a case-control study, we defined 190 women who died from breast cancer as cases and 190 women alive at the time for the corresponding case's death as controls. Inclusion criteria were tumor size <or=50 mm, no lymph node metastases and no adjuvant chemotherapy. Tumor tissues were immunostained for cyclin A using commercially available antibodies.
Results: We found a statistically significant association between expression of cyclin A and breast cancer death in a univariate model: odds ratio for cyclin A(ave) 2.7 [95% confidence interval (CI), 1.7-4.3] and cyclin A(max) 3.4 (CI, 2.1-5.5). Corresponding odds ratio for Ki67 were Ki67(ave) 1.9 (CI, 1.2-3.1) and Ki67(max) 1.7 (CI, 1.1-2.7) and for grade 3.1 (CI, 1.8-5.1). Cyclin A was strongly correlated to Ki67 and grade why a model including all was not appropriate.
Conclusions: Cyclin A is a prognostic factor for breast cancer death in node-negative patients using standardized methodology regarding scoring and cutoff values. Adding cyclin A as a proliferative marker to established clinicopathologic factors will improve the separation of low and high risk breast cancer.