RESUMEN
Success in breast cancer treatment depends greatly upon early detection, and in the employment of prognostic markers able to anticipate the evolution of the disease, allowing a more rational management of the patient. A fundamental cause of cancer is the alteration of the genetic material, which may modify the expression of proteins that play key roles in cell cycle progression. The aim of this study was to analyze the expression of cyclins D1, E, and B1 and of the CDKIs p16 and p21 in a population of uniformly treated patients with stage I or II breast tumors (n=56) compared with patients with benign breast pathology (n=23). Malignant breast tumors showed higher cyclin E and lower p21 expression than benign breast pathology (NS), determined by immunohistochemistry (IHC). In breast cancer patients, overexpression of cyclins D1 and E was associated with the presence of ER and stage respectively independently of other prognostic variables (multivariate analysis). Kaplan-Meier curves demonstrated that only overexpression of cyclin E was associated with a longer recurrence-free survival. Cox analysis showed that neither cyclins nor CDKIs were independent prognostic markers. We demonstrated that several regulators of cell cycle progression were altered in a large number of breast tumor cases, however, these abnormalities were not indicators of a worse outcome in breast cancer patients of stages I and II.