ACCELERATED INDUCTION OF HEPATOMAS IN FAST NEUTRON IRRADIATED MICE INJECTED WITH CARBON TETRACHLORIDE
NAVAL RADIOLOGICAL DEFENSE LAB SAN FRANCISCO CA
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Young adult C57L x AF1 hybrid mice received single whole body exposure to fission spectrum fast neutrons 165-306 rad. Subgroups then received single subcutaneous injections of CCl4, given at 2, 12, 15, or 18 months postirradiation. Control non-irradiated mice received a single injection of CCl4. Other groups of mice were exposed to single 500 rad dose of 250 KVP X-rays. The incidence of hepatomas increased markedly in neutron-irradiated mice 19 compared with X-rradiated mice 2. In neutron-irradiated ice injected with CCl4, hepatoma incidence attained a value of 61, three times that in mice irradiated with neutrons only. In addition, marked pleomorphism and atypicality of liver cell nuclei was evdent in almost all neutron-CCl4 mice, but was observed in only 6 of 47 mice exposed to neutrons only. Of the small group which received CCl4, but no irradiation, and sacrificed up to 22 months later, none exhibited hepatomas or nuclear abnormalities. CCl4 seems to act as a promoting agent in liver carcinogenesis. These findings, and other data in the literature, support the concept that hepatoma induction is accelerated by the action of a specific proliferative stimulus on cells bearing a latent radiationinduced alteration.
- Medicine and Medical Research