The prognostic significance of cyclin D1 expression in patients with triple-negative breast cancer.

Purpose: Breast cancer (BC) is the most common cancer and the second leading cause of cancer death among women. While receptor-targeted therapies are used for other subtypes due to the presence of such receptors, studies are still continuing on receptor expression in order to identify new therapeutic targets as the triple-negative breast cancer (TNBC) lacks a target receptor and its prognosis is worse than the other subtypes. Cyclin D1 (CycD1) is a cell cycle regulator protein. It is stated that its overexpression plays a role in carcinogenesis. With the present study, we aimed to evaluate the prognostic significance of immunohistochemical expression of CycD1 in patients with TNBC.
Methods: The study included 56 operated patients with TNBC who were diagnosed between 2006 and 2011 at Izmir Katip Celebi University, Ataturk Research and Training Hospital, Department of Pathology. In tumor paraffin-embedded sections, CycD1 was immunohistochemically (IHC) studied. Demographic and survival data of the patients were obtained from the Department of Medical Oncology follow-up files. ROC curve analysis was used to calculate the cutoff value for CycD1 staining density. Patients were divided into two groups using 11.5 cutoff value for the expression of CycD1, obtained by ROC analysis. Kaplan-Meier analysis was utilized for survival analyses, and log rank test for comparisons between the two groups.
Results: Of the patients, 62.5% had CycD1 expression (37.5% had not). In the whole group, the 5-year disease-free survival (DFS) was 51%, and the 5-year overall survival (OS) was 65%. No difference in DFS between the two groups was noticed (p=0.37). The 5-year DFS was 47% in the group with CycD1 expression below 11.5, while it was 57% in the group above the 11.5 value. The difference in OS between the groups was statistically significant (p=0.044). The 5-year OS was 55% in the group with a CycD1 expression below 11.5, while it was 79% in the group above the 11.5 value (p=0.044).
Conclusion: OS differed significantly between the high and low-CycD1 expression. It was also demonstrated that CycD1 may have prognostic significance in TNBC. Further studies with larger populations are required to confirm the prognostic significance of CycD1.