Long-term Survival and Tumor Induction After Exposure to High- and Low-LET Radiation

Purpose: To investigate the influence of sex on long-term survival and tumor induction after exposure to high- and low-LET radiation

Status: 1989- 1993 terminated

Treatment: Single exposure to 250 kVp X-rays (126 mGy/min, 1.5 mm HVL) or fission neutrons (0.4 MeV, doses of 0.1 and 0.2 Gy given at a dose rate of 0.08 Gy/min, larger doses at 0.18 Gy/min) from the biological facility of the RSV-TAPIRO reactor at Casaccia.

Dosimetry: Twin ionization chamber method, ENDIP

Endpoints: Life-span study (spontaneous death) with macroscopic/microscopic pathology

Animal: Male and female CBA/Cne mice aged 3 months

Results: As a general finding, male CBA/Cne mice appear more susceptible to tumorigenesis than females. In particular, the incidences of induced acute myeloid leukemia and malignant lymphomas are significant only in male mice. Benign and malignant solid tumors of many types are observed in mice of both sexes, the most frequent being in the lung, liver and ovary. However, evidence for a radiation response is limited to the case of Harderian gland neoplasms. In addition, a comparison of the observed frequency of all irradiated compared to unirradiated animals bearing solid tumors shows that the total tumor occurrence is not altered markedly by radiation exposure. A decrease in survival time is observed for both sexes and radiation types and correlates well with increasing dose. Moreover, both sex and radiation quality appear to influence the life shortening. A similar dose dependence of survival time is found when tumor-free animals alone are considered, suggesting a non-specific component of life-shortening.