Detection of c-Ha-ras oncogene expression in pleural and peritoneal smear effusions by in situ hybridization

This study was undertaken to determine the presence of the c-Ha-ras protooncogene in pleural and peritoneal effusions. Cells from 40 pleural and peritoneal fluids from patients with malignant and nonmalignant diseases were studied by in situ DNA hybridization utilizing a biotinylated probe. The results were correlated with those obtained by conventional cytological methods. A cytological diagnosis of metastatic carcinoma was established in 67% of the patients with malignancy and effusion, and in 6% of the patients with benign disease accompanied by effusion. On the other hand, a relatively high proportion of ras expression was observed in 38% of the cases representing benign and reactive effusions and as high as 88% in the cases with malignant tumor and effusion. These results suggest that the ras oncogene may have an important role in differentially diagnosing benign and reactive mesothelial cells from malignant cells.