Ki-67 Antigen; A Valuable Prognostic Biomarker for Chronic Lymphocytic Leukemia

Background: Chronic lymphocytic leukemia (CLL) is one of the most common blood malignancies. The chief cells involved in this malignancy are in the G0 phase of cell division and have no proliferative activity; however, what determines the severity and prognosis of this disease is cell proliferation. Ki-67 antigen is a nuclear protein that is present in all cell proliferative phases except G0. The present study was aimed to investigate the prognostic value of Ki-67 antigen expression in patients with CLL and their disease behavior. Methods: The current cross-sectional study has been conducted on 50 CLL patients in 2017. The disease severity based on Rai's staging system, lymphadenopathy, organomegaly, and complete blood count and differentiation (CBC diff) were assessed at study initiation and within six months. Besides, Ki-67 antigen level was assessed via flow-cytometry. Eventually, the prognostic value of Ki-67 antigen to determine CLL prognosis was assessed utilizing Receiver operation curve (ROC) Findings: The study population had the mean age of 64.12 ± 10.42 years old and predominantly consisted of males (68%), and had the mean Ki-67 antigen level of 2.48 ± 1.73 (%). Rai's stage deterioration to 3 or 4, organomegaly, white blood cells (WBC) doubling and concurrent Rai's staging deterioration and WBC doubling (P = 0.002) were directly associated with Ki-67 antigen levels. At the cut-point of 3.44%, Ki-67 antigen had the sensitivity and specificity of 87.5% an 92.9%, with area under the curve (AUC) 0f 0.940 (95%CI: 0.835-0.988; P < 0.001). Conclusion: According to this study, Ki-67 antigen is a valuable prognostic biomarker for CLL progression activity. Besides, at the cut-point of 3.44%, Ki-67 antigen had an acceptable predictive value for the progression manner of CLL disease.