Association between Serum Levels of Interleukin-6 and Stage of Laryngeal Cancer

The purpose of this study was to investigate the relationship between serum levels of interleukin-6 (IL-6) and the severity and extent of squamous cell carcinoma (SCC) of the larynx based on stage of tumor progression and histological grade. All patients with a diagnosis of laryngeal cancer who underwent laryngoscopy and biopsy while hospitalized in Imam Khomeini Hospital in Ahvaz were enrolled. Tumor stage was calculated based on the TNM system, and divided into early (stage 1,2) or advanced stage (stage 3,4). In addition, patients were divided into low-grade (well differentiated) or high-grade (moderate and poorly differentiated) groups based on pathology reports from biopsy specimens. Several healthy volunteers were also enrolled as the control group. After collecting the blood samples, quantitative serum levels of IL-6 were measured (pmol/L) using IL-6 kits (Bender MedSystem, Germany). Results for quantitative variables are presented as mean and standard deviation and qualitative variables as percentages. Mann-Whitney, Kruskal-Wallis and Pearson’s chi square tests were used for statistical analyses. Thirty-eight patients (82.6%) were male and eight patients (17.4%) were female. IL-6 serum level was 28.8±4.7 pmol/L in the patient group and 2.64±2.88 pmol/L in the control group (P=0.0001). The serum level of IL-6 was 7.27 ± 5.31 pmol/L in early-stage patients and 54.43 ± 6.06 pmol/L in advanced-stage patients (P<0.0001). IL-6 levels increased significantly with increasing N (according to TNM) (P=0.002). Levels of IL-6 in patients with metastasis were significantly higher than in the group without metastasis (P=0.024). Moreover, IL-6 levels increased significantly with increasing local tumor spread (T) (P<0.0001). This study shows that IL-6 is a gender-independent factor, serum levels of which are higher in patients with laryngeal SCC than in normal subjects. The results of this study also show that serum levels of this cytokine increase significantly with progression of this malignancy.