Abstract:
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There are various highly-penetrant familial cancer syndromes with elevated leukemia risk, and evidence for familial clustering of other common cancers. Myeloid leukemia is highly radiogenic, but there is little evidence that induction by high-energy irradiation, typical of radiation exposures in outer space, is markedly more effective than low-energy radiation. We used a Cox model with familially-structured random effects to assess fifteen separate cancer endpoints, in a group of 1850 mice in 47 families maintained in a circular breeding scheme, exposed to accelerated high energy silicon-28 (Si) (240 MeV) or iron-56 (Fe) (600 MeV) ions, or cesium-137 gamma-rays. There is periodicity in the effect of familial relatedness, which is most pronounced for pulmonary adenoma, Harderian-gland adenoma, Harderian-gland tumor, ectodermal tumor, pulmonary adenocarcinoma and hepatocellular carcinoma (p=0.0001/0.0003/0.0017/0.0035/0.0257/0.0340 respectively) with families that are 3-4 generations apart most strongly correlated; myeloid leukemia also exhibited a striking periodic correlation structure. The effects per unit dose of high-energy beams are less than 9 x those of lower energy gamma.
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