Background & objectives: According to the new theory of cancer stem cells, interruption in the self-renewal pathway of tissue stem cells can cause cancerous tumors. Current work has evaluated the role of self-renewal Oct-4 gene in thyroid tumors.

Methods: In this case-control study, the expression of Oct-4 gene has comparatively assessed between cancerous specimens, marginal tissues of tumors and non-tumoral nodules of thyroid using RT-PCR technique.

Results: Statistical analysis of data by one-way ANOVA showed that Oct-4 gene is significantly expressed in thyroid papillary carcinomas in comparison with tumor margin and non-tumoral nodules (p<0.05).

Conclusion: In conclusion, the dominant expression of Oct-4 gene in thyroid tumoral cells not only demonstrates the cancer stem cell theory but also shows its role in thyroid cancer appearance that can be used in differentiating thyroid papillary carcinomas from non-tumoral nodules as well as demarcation of tumors.