Salivary Interleukin Levels in Oral Squamous Cell Carcinoma and Oral Epithelial Dysplasia: Findings from a Sri Lankan Study

SIMPLE SUMMARY: The incidence of oral cancer is increasing with little improvement in survival. This is due to late diagnosis with most cases diagnosed at a stage beyond a cure. In Sri Lanka, oral cancer is the most common cancer in males, carrying a high mortality rate. Identifying markers that can help in early detection is important for improving patient outcome. Here, we present findings from a study in Sri Lanka that assessed salivary interleukins in oral cancer and precancer patients compared to disease-free controls. Our results clearly show that the salivary protein levels of these interleukins progressively increase from disease-free participants through different grades of dysplasia with the highest levels reported in cancer patients. This has significant clinical potential, as assessment of salivary levels of these interleukins can be developed into non-invasive risk assessment tools for detecting disease progression in dysplasia, and as screening tests for early detection of oral cancer. ABSTRACT: The incidence of oral squamous cell carcinoma (OSCC), and its precursor, oral epithelial dysplasia (OED), is on the rise, especially in South Asia. OSCC is the leading cancer in males in Sri Lanka, with >80% diagnosed at advanced clinical stages. Early detection is paramount to improve patient outcome, and saliva testing is a promising non-invasive tool. The aim of this study was to assess salivary interleukins (lL1β, IL6, and IL8) in OSCC, OED and disease-free controls in a Sri Lankan study cohort. A case-control study with OSCC (n = 37), OED (n = 30) patients and disease-free controls (n = 30) was conducted. Salivary lL1β, IL6, and IL8 were quantified using enzyme-linked immuno-sorbent assay. Comparisons between different diagnostic groups and potential correlations to risk factors were assessed. Salivary levels for the three tested interleukins increased from disease-free controls through OED, and were highest in OSCC samples. Furthermore, the levels of IL1β, IL6, and IL8 increased progressively with OED grade. The discrimination between patients (OSCC and OED) and controls, as assessed by AUC of receiver operating characteristic curves, was 0.9 for IL8 (p = 0.0001) and 0.8 for IL6 (p = 0.0001), while IL1β differentiated OSCC from controls (AUC 0.7, p = 0.006). No significant associations were found between salivary interleukin levels and smoking, alcohol, and betel quid risk factors. Our findings suggest that salivary IL1β, IL6, and IL8 are associated with disease severity of OED, and are potential biomarkers for predicting disease progression in OED, and the screening of OSCC.