| Background and objective:Thymic epithelial tumor (TET) is a kind of originated in the thymus epithelial cell tumor, which is the most common anterior mediastinum of adult, as accounting for about20%of the adult mediastinal tumor. It is one of the most common mediastinal tumor. Podoplanin, originally detected on the surface of podocytes, belongs to the family of type-1transmembrane sialomucin-like glycoproteins. Although specific for lymphatic vascular (LV) endothelium, podoplanin is expressed in a wide variety of normal and tumor cells. D2-40in lymphatic endothelial cell (LECs) was used in many studies to evaluate the LV microvascular density (LVMD) in peritumoral and tumoral areas, and to correlate LVMD with lymph node status and prognosis. D2-40expression was found in tumor cells of various types of cancer, such as vascular tumors, malignant mesothelioma, tumors of the central nervous system (CNS), germ cell tumors and squamous cell carcinomas. There are few studies about the expression of D2-40in the thymic epithelial tumor. Immunohistochemical method was used to detect the expression of D2-40in TET and their putative significance in the invasion and metastasis, to further explore the possible mechanism of metastasis of TET.Methods:Collect January1992to January2006in shandong province hospital operations to remove thoracic surgery and confirmed by pathology for thymic lesion and160cases of thymic carcinoma paraffin specimens. All of cases contions119thymus tumor and41thymic carcinoma. Take20cases of normal children the thymus and20adults atrophy the thymus for normal controls, which take from heart surgery patients. Detect D2-40by the immunohistochemical S-P method in160cases of different types and staging TET, and40patients with normal thymus tissue of expression. Use SPSS17.0software based on the database to be analyzed. D2-40expression used chi-square test. Kaplan-Meier method was performed to calculate the survival rate. Log-rank method was performed to compare the survival difference between the patients with and without D2-40expression. Cox regression multivariate analysis was performed to determine independent prognostic factor. Differences were considered significant when the P value was less than0.05.Results:1. The normal group:40cases, the ages of the children thymus20cases patients ranged from0.8tol5years, with an average of55.1±3.4years. The ages of the adult atrophy thymus20case patients ranged from23to48years, with an average of32.5±6.8years.TET groups:The ages of the160patients ranged from15to78years, with an average of48.4±12years.2. The pathological and histological characteristics:The tumors consisted of10type A,24type AB,26type B1,42type B2,12type B3,5combined thymomas and41according to the World Health Organization histological classification system and of51stage Ⅰ,32stage Ⅱ,58stage Ⅲ,5stage IVa, and14stage IVb thymomas according to the Masaoka staging system. The tumors ranged in size from2to20cm in maximum dimension (median,7cm). Thirty-six tumors were smaller than5cm, and twenty-four tumors were larger than10cm. There was a statistically significant association between tumor size and clinical stage (P=0.017), whereas no association was established between tumor size and histological subtype (P=0.098).3. D2-40expression:D2-40in normal the thymus and the TET expression rate respectively were20%(8/40),58.8%(66/160), and the difference is statistically significant (.P=0.013). In the noninvasive TET and aggressive in the TET expression rate respectively were5.9%(3/51),63.6%(63/99), and the difference was statistically significant (P<0.01). D2-40of the expression and the relevant age (P<0.001). Patient gender, tumor size, and myasthenia gravis were not associated with D2-40expression, 4. Survival analysis:Actuarial5-years survival of160TET cases was63%. Actuarial5-years survival of D2-40express positive and negative groups were32%,90%(P<0.001). The Kaplan-Meier survival curves according to the prognostic factors are shown that statistically significant differences were observed in the clinical stages (P<0.001), pathology organization credits type (P<0.001), tumor size (P=0.005) and D2-40expression (P<0.001). The results of Cox regression multivariate analysis conformed that the clinical stage (P=0.002, relative risk7.055), pathology organization credits type (P=0.004, relative risk6.755) and D2-40expression (P=0.008, relative risk3.069) was independent factors.Conclusions:1. Normal thymus organization and thymic epithelial tumor tissue are visible D2-40of positive expression, but thymic epithelial tumor tissue of the expression was significantly higher than the normal thymus organization.2. Masaoka increased with the staging, thymic epithelial tumor tissue D2-40express positive and strength corresponding increase, that is D2-40of the expression with the TET invasive enhance and strengthen.3. The expression of D2-40and the thymus tumor patient age, the clinical stages, organization credits type and relative and gender, tumor size, and whether has nothing to do with myasthenia gravis.4. Cox regression analysis results showed that the more factors the clinical stage (P=0.002, relative risk7.055), pathology organization credits type (P=0.004, relative risk6.755) and D2-40expression (P=0.008, relative risk3.069) is the independent factors affecting the prognosis.5. The expressions of D2-40tested by immunohistochemistry could be used to explore and evaluate the latent of invasion and metastasis of TET, and provide some evidence for the further studying and treatment of TET. |
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