<正> Objective: To study the expressions and clinical significances of PCNA

EGFR

Bcl-2 and Bax in thymoma. Methods: The expressions of EGFR

PCNA

Bcl-2 and Bax in 46 cases of thymoma and 11 cases of normal thymus were detected with S-P immunohistochemistry. The results were analyzed with the pathologic indexes. Results: The positive rates of EGFR

Bcl-2 and Bax in normal thymus were 18. 2%

9.1%

and 18. 2% respectively

while in thymoma were 71. 7%

41. 3%

and 15. 2% separately. The expression of EGFR in thymoma was significantly correlated with Masaoka staging and Levine classification. The survival rate of EGFR negative patients was significantly higher than that of EGFR positive patients （P<0. 01）. PCNA labelling index was significantly higher in thymoma as （4. 00±1. 87）% than in normal thymus

（2. 68± 0. 62）%

which was significantly correlated with Levine classification. The expression of Bcl-2 in thymoma was also significantly correlated with Levine classification. The survival rate of Bcl-2