Saliva protein biomarkers to detect oral squamous cell carcinoma in a high-risk population in Taiwan

Oral squamous cell carcinoma (OSCC) accounts for 90% of oral cancers, and earlier detection efficiently increases the survival rate. Here, we used a comprehensive literature review to select candidates and used LC-multiple reaction monitoring-MS to qualitatively and quantitatively measure target proteins in saliva samples from individuals of the at-risk population in Taiwan. Statistical analysis of the results establishes a four-protein panel sufficient to detect 88.6% of early-stage patients and 91.6% of all patients with 80.4% specificity. This panel can also be used to evaluate the risk of malignant progression from high-risk oral potential malignant disorder. Our study offers a practical foundation for clinical trials examining the ability of this panel to enable early detection of OSCC, risk assessment for cancer development, and treatment monitoring.

Most cases of oral squamous cell carcinoma (OSCC) develop from visible oral potentially malignant disorders (OPMDs). The latter exhibit heterogeneous subtypes with different transformation potentials, complicating the early detection of OSCC during routine visual oral cancer screenings. To develop clinically applicable biomarkers, we collected saliva samples from 96 healthy controls, 103 low-risk OPMDs, 130 high-risk OPMDs, and 131 OSCC subjects. These individuals were enrolled in Taiwan’s Oral Cancer Screening Program. We identified 302 protein biomarkers reported in the literature and/or through in-house studies and prioritized 49 proteins for quantification in the saliva samples using multiple reaction monitoring-MS. Twenty-eight proteins were successfully quantified with high confidence. The quantification data from non-OSCC subjects (healthy controls + low-risk OPMDs) and OSCC subjects in the training set were subjected to classification and regression tree analyses, through which we generated a four-protein panel consisting of MMP1, KNG1, ANXA2, and HSPA5. A risk-score scheme was established, and the panel showed high sensitivity (87.5%) and specificity (80.5%) in the test set to distinguish OSCC samples from non-OSCC samples. The risk score >0.4 detected 84% (42/50) of the stage I OSCCs and a significant portion (42%) of the high-risk OPMDs. Moreover, among 88 high-risk OPMD patients with available follow-up results, 18 developed OSCC within 5 y; of them, 77.8% (14/18) had risk scores >0.4. Our four-protein panel may therefore offer a clinically effective tool for detecting OSCC and monitoring high-risk OPMDs through a readily available biofluid.