Usefulness of salivary sialic acid as a tumor marker in tobacco chewers with oral cancer

Aim:This study aims to assess the usefulness of salivary sialic acid (SA) as a tumor marker in the detection of oral squamous cell carcinoma (OSCC) among tobacco chewers. Materials and Methods:After the approval of study protocol by the Institutional Ethics Committee and informed voluntary consent, salivary samples were collected from 96 participants in each group of tobacco chewers with OSCC, tobacco chewers without precancerous or cancerous lesion, and healthy controls. Salivary protein-bound SA (PBSA) and salivary-free SA (FSA) were measured by Yao et al.'s method of acid ninhydrin reaction, and the data were subjected to appropriate statistical analysis. Results: The salivary PBSA and FSA levels in the Groups 1, 2, and 3 participants were 31.17 ± 7.6 mg/dL and 63.45 ± 9.8 mg/dL, 25.45 ± 16.61 mg/dL and 33.18 ± 11.38 mg/dL, and 22.73 ± 3.01 mg/dL and 21.62 ± 8.86 mg/dL, respectively. Salivary FSA levels were significantly increased among the tobacco chewers with OSCC patients (Group 1) and tobacco chewers with no premalignant lesions of the oral cavity (Group 2) compared to the healthy controls (Group 3) with P < 0.05 being statistically significant. Salivary FSA levels were significantly increased in Group 1 as compared with Group 2. The salivary PBSA was high among Group 1 as compared to the control Group 3; there was however no significant difference in the levels of salivary PBSA between Group 1 and Group 2. There was no significant difference in the PBSA levels between OSCC patients of Group 1 and the tobacco chewers without precancerous or cancerous lesion in the oral cavity of Group 2. Conclusion: Salivary PBSA and FSA are significantly raised in both tobacco chewers with OSCC and in tobacco chewers with no precancerous or cancerous lesions in the oral cavity. SA should therefore be used cautiously while considering it as a marker for the early detection of oral cancer. Tobacco can be a crucial confounding factor when SA is used as a biomarker in OSCC since their levels are elevated to some extent even in tobacco chewers without any clinically obvious precancerous or cancerous lesions in the oral cavity.