Aim: The current study targets linking serum and salivary dipeptidyl peptidase-4 with oral squamous cell carcinoma and comparing it with potentially malignant lesions and control to validate dipeptidyl peptidase-4 as a diagnostic marker for early detection of oral cancer and to reveal its possible role in carcinogenesis.

Methodology: A total of 45 patients were recruited and subdivided into 2 groups: Group I: 15 patients having oral squamous cell carcinoma. Group II: 15 patients with potentially malignant lesions (leukoplakia and oral lichen planus) compared to 15 systemically healthy participants having no oral mucosal lesions acting as a control group (Group III). Serum and whole unstimulated salivary samples were collected from all participants to evaluate dipeptidyl peptidase level in different groups using enzyme linked immune-sorbent assay (ELISA) kit. ROC analysis was done to reveal area under the curve, sensitivity, specificity and diagnostic accuracy of DPP-4 among different groups.

Inclusion Criteria:

• systemically healthy
• No current medication,
• both genders with age ranging from 30 to 65 years old.
• having oral leukoplakia, oral lichen planus or oral squamous cell carcinoma

Exclusion Criteria:

• systemic disease
• pregnancy
• lactation
• being diagnosed with any other oral mucosal lesion

adult individuals entering in the out patient clinics of oral medicine and diagnosis department