Prognostic significance of Tiam1 expression in papillary thyroid carcinoma.

T lymphoma and metastasis gene 1 (Tiam1) is a guanine nucleotide exchange factor (GNEF) that regulates the guanosine triphosphatase to facilitate the exchange of guanosine diphosphate for guanosine triphosphate. It specifically activates Rac1, a member of the Rho family of GTPases. Tiam1 is involved in cell proliferation, cytoskeletal organization, cellular adhesion, and transcriptional activation. It has been suggested that alterations in Tiam1 expression might contribute to the progression of various human cancers. The usefulness of Tiam1 expression as a prognostic marker in papillary thyroid carcinoma (PTC) has not been investigated yet. The aim of this study was to analyze the expression of Tiam1 in PTC as well as its association with the clinicopathologic features and prognostic significance. Surgical tissue samples were taken from 106 PTC patients who had been followed up for at least 9.3 years. Strong expression of Tiam1 was detected in 54% of the cases. Tiam1 expression was associated significantly with various clinicopathologic parameters, such as gender (P=0.039), tumor multicentricity (P=0.0124), histologic subtype (P=0.0427), TNM stage (P=0.0151), and distant metastases at diagnosis (P=0.0001). Survival analysis showed that the Tiam1 low-expression group had a significantly shorter overall survival time than Tiam1 high-expression group (P=0.0007). Multivariate analysis showed that Tiam1 expression was a significant and independent prognostic indicator (P=0.0090) for PTC patients. Tiam1 expression may be a novel and independent prognostic marker of PTC patients. © Springer-Verlag 2011