BCG therapy of pleural and peritoneal growth of transplanted rat tumours.

Growth of intrapleurally injected cells of immunogenic methylcholanthrene-induced rat sarcomas was suppressed by intrapleural injection of viable or 1 times 10-6 R radiation-sterilized BCG vaccine. As little as 10 mug moist weight of organisms was effective, and treatment could be given several days before or after tumour challenge. Pleural effusion growth of a moderately immunogenic ascitic hepatoma was also controlled by intrapleurally administered BCG. In contrast, BCG injected intravenously, subcutaneously or intraperitoneally was without influence on pleural tumour growths. Similarly, intraperitoneal growth of these tumours was suppressed only by intraperitoneal injection of BCG. With two other transplanted tumours, a chemically induced mammary carcinoma and a spontaneous sarcoma, both of which lack significant immunogenicity, BCG treatment of pleural and peritoneal growths was less successful and more variable. Nevertheless, these studies indicate the potential of this type of treatment of thoracic and peritoneal tumour deposits for possible clinical application in the treatment of malignant mesothelioma.