Diffuse and continuous cell proliferation enhances radiation-induced tumorigenesis in hamster lung.

Syrian Golden hamsters received 8 weekly intratracheal instillations of 0.2 microCi of the alpha-emitting isotope Po210 while being exposed to an atmosphere of 65% oxygen in the inspired air. Three months later, 42% of the animals had poorly differentiated lung carcinomas. On the other hand, no lung tumors were found in hamsters that received intratracheal instillations of Po210 and were kept in air. It is concluded that diffuse cell hyperplasia in the lung, caused by an inhalant, may constitute an additional risk factor in the pathogenesis of alpha-radiation induced lung cancer.