The downregulation of Rap1 GTPase-activating protein is associated with a poor prognosis in colorectal cancer and may impact on tumor progression.

Rap1 GTPase-activating protein (Rap1GAP) has been reported to serve an important role in various types of cancer by specific stimulation as a negative regulator of Rap1 activity. However, the role of Rap1GAP in colorectal cancer (CRC) has yet to be fully elucidated. The aim of the present study was to investigate the expression of Rap1GAP in CRC tissues and to elucidate its clinical significance. The expression of Rap1GAP, matrix metallopeptidase 9 (MMP-9) and E-cadherin in 227 CRC tissues and paired para-carcinoma tissues was detected by immunohistochemistry. Associations between Rap1GAP expression and clinicopathological characteristics, and between Rap1GAP expression and prognostic value (OS + DFS) in CRC were investigated. Furthermore, associations between Rap1GAP expression and MMP-9 expression, and between Rap1GAP expression and E-cadherin expression were also investigated. Rap1GAP expression was markedly downregulated in CRC tissues compared with para-carcinoma tissues. Decreased expression of Rap1GAP was significantly associated with depth of invasion, lymph node metastasis, advanced Tumor-Node-Metastasis stage and a poor prognosis in patients with CRC following surgery. Furthermore, univariate and multivariate analyses revealed that Rap1GAP was an independent poor prognostic factor for disease-free survival and overall survival. In addition, Rap1GAP expression was negatively associated with MMP-9 and positively associated with E-cadherin in 227 CRC samples. In brief, the results of the present study suggested that Rap1GAP may be involved in tumor progression in CRC and may serve as a potential target for prognostic prediction of patients with CRC.

[Evaluation of lymph node dissection in the central neck area in managing thyroid microcarcinoma].

OBJECTIVE: To evaluate lymph node dissection in the central neck area to treat micro-sized thyroid carcinoma. METHODS: The clinical data of 65 surgically treated thyroid microcarcinoma patients in our hospital were retrospectively reviewed. RESULTS: In this series, the positive metastasis rate of cervical lymph node was 40%. A total of 62 patients had been followed up until the data were reviewed. None was found to be dead nor having distant metastasis. Five patients were re-operated due to countralateral lobe meatstasis 3 years after initial operation, 2 of them had developed para-tracheal lymph node metastasis; another 2 cases underwent functional neck lymph node dissection due to lymph node metastasis on the operated side 2 years later. CONCLUSION: Thyroidectomy with lymph node dissection of the central neck area is more effective than the thyroidectomy alone for managing thyroid microcarcinoma. It can improve the quality of life and survival through reducing cervical lymph node metastasis.