KI-67 AS A MARKER OF RESPONSE TO TREATMENT FOR EMBRYONAL TUMORS
Antigen Ki-67 is a nuclear protein expressed in proliferating mammalian cells. It is widely used in cancer histopathology but its functions remain unclear. This article demonstrates that Ki-67 is a marker of response to chemotherapeutic treatment in patients with embryonal tumors. Changes in Ki-67 expression significantly affect the prognosis of treatment of pediatric embryonal tumors. There are three types of tumor response to chemotherapy treatment: stabilization, regression, and progression. This retrospective study was performed on tumor tissue samples obtained at verification of the tumor process and on tumor tissue samples obtained at stage II of special treatment (surgical treatment, surgical material) after polychemotherapy. The study demonstrated that proliferative activity of Ki-67 after special treatment in patients with progression of the underlying disease was higher than the levels at verification of the tumor process; and vice versa, low levels of proliferative activity were noted after special treatment in patients with tumor regression. In patients with stabilization of the tumor process, proliferative activity did not change significantly between the stages of tumor process verification and surgical treatment. Overall, our results suggest that Ki-67 expression can serve as a prognostic factor for evaluating the effectiveness of treatment in children with embryonal tumors.