Influence of γ irradiation on the development of neoplastic disease in mice. I. Reticular tissue tumors

The influence of ¹³⁷Cs γ irradiation on the development of reticular tissue neoplasms was investigated using male and female RFM/Un mice. The relationship between radiation dose and incidence of thymic lymphoma for females was complex, and no simple model described the relationship over the entire dose range. Over the range 0 to 25 rad linearity could be rejected and a dose-squared model described the data, while over the range 50 to 300 rad the response was linear. Males were less sensitive to induction of thymic lymphoma than females and their dose-response relationship was less complex with a linear response predominating. Males were more sensitive than females to induction of myeloid leukemia, with the age-adjusted incidence at 300 rad reaching 20% in males but only 5% in females. The response was linear for both sexes. The age-adjusted incidence of reticulum cell sarcoma decreased with dose in both male and female mice. The role of host factors in determining the type of neoplasm as well as the form of the dose-response relationship is discussed.