AN IMMUNOCYTOCHEMICAL STUDY OF RAS AND MYC ONCOPROTEINS AND EGFR EXPRESSION IN PLEURAL EFFUSION SMEARS

Pleural effusion smears from 112 patients with either benign or malign ant lung disease were investigated for the expression of EGFr and the oncogene proteins myc p64 and ras p21. The streptavidin-biotin peroxid ase technique was used. In the studied malignant group of effusions bo th EGFr and ras have greater sensitivity in the detection of a maligna nt process than does routine cytological examination though EGFr was l ess specific. The combination of positive cytology and 3 positive mark ers is highly specific for a malignant process (90%). Myc and ras had a 100% sensitivity in squamous cell carcinomas but an overall specific ity of only 67.3% and 66.6% respectively. The differences in myc and m s positivity, between squamous cell and adenocarcinoma effusion smears were highly significant (p <0.005). All effusion smears associated wi th undifferentiated carcinomas were ras positive and 2 of them were my c and EGFr positive.