IL-2 and IL-12 in thyroid cancer: Clinical implication

Abstract

Purpose: The roles of IL-2 and IL-12, in different malignancies have been looked for since years. But very few studies have elucidated their role in thyroid tumorigenesis. Hence, present study sought to explore their utility in thyroid cancer, mainly the papillary thyroid cancer (PTC). Methods: A total of 67 patients with benign thyroid diseases, 106 with thyroid cancer and 67 healthy individuals were included in the study. Circulating levels of IL-2 and IL-12 were estimated by ELISA from all patients and controls. Protein expression of both interleukins was determined using immunohistochemistry. The results were statistically analysed using SPSS software. Results: Serum IL-12 exhibited good discriminatory efficacy between patients with benign thyroid diseases and healthy individuals. IL-2 and IL-12 levels could efficiently differentiate PTC and anaplastic thyroid cancer (ATC) patients from healthy individuals. Additionally, IL-12 showed good discriminating efficacy between PTC and benign thyroid disease patients and IL-2 well discriminated ATC patients from benign thyroid diseases. IL-2 was significantly higher in patients having unilateral tumors (P=0.006) while, IL-12 was significantly higher in patients with smaller tumor size (P=0.036) and early stage disease (P=0.008). The cytokine protein expressions in benign thyroid tissues and carcinoma did not differ significantly. IL-12 expression was significantly higher in male patients (P=0.042) and unilateral tumors (P=0.031).Kaplan-Meier survival analysis revealed that nuclear IL-2 expression was able to predict disease free survival and overall survival (OS) in subgroup of PTC patients having multifocal tumors and only OS in patients having bilateral tumors. Moreover, higher IL-12 immunoreactivity was a significant predictor of shorter OS in PTC patients treated with surgery alone. Conclusion: Serologic determination of IL-2 and IL-12 may help in validating indeterminate FNAC results and disclose diagnostic difference between benign and malignant thyroid diseases. However, a large cohort study is mandatory to establish a defined cut off for such discrimination.