Evaluation of Cyclin-Dependent Kinase 4 (CDK4) in the Serum of Thyroid Cancer Patients and Its Association with Oxidative and Antioxidative Factors

The study addressed key medical aspects, particularly the biochemical variables in patients with early-stage (Stage I and II) thyroid cancer, by analyzing blood serum samples. 130 samples were collected from patients in the range of 30 to 70 years. Among them, 60 patients were diagnosed as having papillary thyroid carcinoma by specialists and were undergoing treatment at the Oncology and Nuclear Medicine Hospital, while 70 were healthy individuals who served as controls. The subjects were divided into four groups: 30–39, 40–49, 50–59, and 60–70 years. They were also segregated into two groups based on the severity of the disease: Stage I and Stage II. Biochemical factors investigated included Cyclin-Dependent Kinase 4 (CDK4), uric acid, vitamin E, malondialdehyde (MDA), glutathione (GSH), and peroxynitrite (ONOO⁻). Linear correlation test was employed to find out if there was a correlation between CDK4 and oxidative/antioxidative parameters in the patient and control groups. The results revealed greater concentrations of CDK4, MDA, and peroxynitrite in the patient group compared with the control group. Glutathione, vitamin E, and uric acid concentrations, on the other hand, were found to significantly reduce. In the control group, statistically significant relationships were established between CDK4 and all variables (uric acid, GSH, MDA, vitamin E, and ONOO⁻), with positive relationships with antioxidants and negative relationships with oxidative stress markers. Among patients following thyroidectomy, significant negative correlations were found between CDK4 and both uric acid and MDA, while a positive correlation was observed between CDK4 and vitamin E. No significant correlations were found between CDK4 and either glutathione or peroxynitrite, which may indicate a disruption in oxidative balance post-surgery.