The potential of ki67 and p53 assessment in development of individualized targeted therapy in breast cancer patients

Introduction. Despite the improvement of diagnostic methods and chemotherapeutic regimens in breast cancer, overall 5-year survival significantly depends on the stage of the disease. Over expression of tumor suppressor gene p53 and the marker for cellular proliferation Ki67 in breast cancer may have prognostic significance. Methods. We evaluated 675 patients diagnosed with breast cancer at UF Health Jacksonville between January 2000 and June 2007 with up to 5-year follow up. The aim of the study was to determine whether immunohistochemical (IHC) assessment of Ki67 and p53 may predict outcome, the 'hazard' of dying. Cox's proportional hazards models were used to control for age (< 50 vs. ≥ 50), race (white vs. other), lymph node group (negative vs. positive), ER (estrogen receptor) group (negative vs. positive), PR (progesterone receptor) group (negative vs. positive), and tumor type. Results. When only p53 was considered in the model, the hazard of dying was significantly higher for p53 positive compared to p53 negative (HR = 1.32, 95 % CI 1.02, 1.70, p = 0.036). When only ki67 was considered in the model, the hazard of dying was significantly higher for ki67 positive compared to ki67 negative (Hazard ratio = 1.64, 95 % CI 1.08, 2.49, p = 0.021). Neither of the two markers, nor their interaction was significant when all variables were considered in the model. Discussion. This study confirms the expression of p53 and Ki67 as strong individual indicators of patient outcome. However, when controlling for the other variables, the two markers are not independent predictors. Future studies that will include these markers might help design targeted therapy.