STUDIES OF RADIATION-INDUCED CANCER

本项目（1）研究暴露于以下物质的人群的癌症风险： 电离辐射，特别是低剂量;（2）风险特征 在剂量反应、辐射质量、 剂量、暴露后时间、性别、暴露和观察时年龄， 和宿主因子的影响; （3）检查、测试和制定辐射模型 致癌作用，以帮助确定基本机制。 研究群体 包括日本原子弹爆炸的幸存者， 治疗的（例如，宫颈癌），诊断（例如， 肺结核），职业性（例如，X射线技术人员）和 环境（例如，氡）暴露。 项目成员服务 为政府和国际机构提供咨询的委员会。 研究结果表明：（1）对放射性物质的敏感性 乳腺癌随着暴露年龄的增加而下降，剂量 反应是线性的，风险至少保持40年;（2） 反复暴露在相对较低的辐射剂量下， 乳腺癌的未来风险，但显然不是肺癌;（3） 高剂量辐射诱发的白血病比其他类型的 暴露;细胞杀伤似乎发挥重要作用， 确定剂量-反应关系;（4）宫颈癌放疗 癌症还增加了直肠癌，膀胱癌， 阴道，胃和甲状腺;（5）诊断X射线可能不是 与白血病或淋巴瘤有因果关系，但仅与 预示其发育的条件;（6）受辐射的儿童 对于良性疾病，有甲状腺和大脑发育的风险 （7）乳腺癌的放射治疗并没有增加 白血病的风险;（8）霍奇金病的放射治疗增加 乳腺癌的风险;（9）儿童癌症的放射治疗 增加随后的骨癌;（10）诊断X射线工作者， 中国是白血病的高风险国家;（11）约9%的 肺癌死亡可能是由于室内氡;（12）低剂量 放射性碘似乎不会增加甲状腺疾病的风险。 癌

This project (1) examines cancer risk in populations exposed to ionizing radiation, especially at low doses; (2) characterizes risk in terms of dose response, radiation quality, fractionation of dose, time since exposure, sex, age at exposure and at observation, and modifying influences of other environmental and host factors; and (3) examines, tests, and formulates models of radiation carcinogenesis to help define basic mechanisms. Groups studied include the Japanese A-bomb survivors, and populations with therapeutic (e.g., cervical cancer), diagnostic (e.g., tuberculosis), occupational (e.g., x-ray technologists) and environmental (e.g., to radon) exposures. Program members serve on committees advising the government and international agencies. Results of studies suggest that (1) susceptibility to radiogenic breast cancer declines with increasing age at exposure, the dose response is linear, and risk remains for at least 40 years; (2) repeated exposure to relatively low radiation doses poses some future risk of breast cancer but apparently not lung cancer; (3) high-dose radiation induces fewer leukemias than other types of exposure; cell-killing appears to play an important role in defining dose-response relationships; (4) radiotherapy for cervical cancer also increases the risk of cancers of the rectum, bladder, vagina, stomach and thyroid; (5) diagnostic x-rays may not be causally related to leukemia or lymphoma but simply related to conditions that portend their development;(6) children irradiated for benign conditions are at risk of developing thyroid and brain neoplasia; (7) radiotherapy for breast cancer did not increase the risk of leukemia; (8) radiotherapy for Hodgkin's disease increased the risk of breast cancer; (9) radiotherapy for childhood cancer increased subsequent bone cancer; (10) diagnostic xray workers in China are at high risk of leukemia; (11) approximately 9% of all lung cancer deaths may be due to indoor radon; and (12) low-dose radioactiveiodine does not appear to increase the risk of thyroid cancer.