STUDIES OF RADIATION-INDUCED CANCER

本项目（1）调查了 受电离辐射，特别是低剂量辐射的人口 （2）确定了辐射诱发癌症的风险， 组织风险、剂量反应、辐射质量， 剂量分次、暴露后时间、性别、暴露时年龄 和观察，以及其他可能的修改影响， 环境和宿主因素;（3）检查。测试和 制定辐射致癌模型，以帮助定义 基本机制。 研究的群体包括日本原子弹 幸存者，以及几个记录在案的 治疗的（例如，宫颈癌患者），诊断（例如， 结核病患者），和职业（例如，x射线 技术人员）暴露于电离辐射。 计划会员 担任政府咨询委员会成员， 国际机构。 研究结果表明：（1）对放射性物质的敏感性 乳腺癌发病率随年龄增长而下降， 10岁以下的儿童处于高风险中;风险为8-16拉德 （2）对骨盆的高剂量辐射引起 比其他类型的暴露更少的白血病;细胞杀伤 似乎在定义剂量反应中起重要作用 （3）反复暴露于相对较低的辐射 剂量会造成一些乳腺癌和甲状腺癌的未来风险，但 非肺癌;（4）儿童因良性疾病接受放射治疗， 头部和颈部有甲状腺和大脑发育的风险 肿瘤;（5）9%的甲状腺癌可归因于 儿童期放疗;（6）儿童期癌症放疗 与随后的骨癌、结缔组织癌 组织和甲状腺，但不是白血病;（7）放线菌素D不 似乎可以预防辐射引起的甲状腺癌;（8） 肾上腺辐射可能降低乳腺癌风险;（9） 局部照射后染色体畸变 持续存在于循环淋巴细胞中超过30年。

This project (1) examines cancer incidence and mortality among populations exposed to ionizing radiation, especially at low dose levels; (2) characterizes the risk of radiation-induced cancer in terms of tissues at risk, dose response, radiation quality, fractionation of dose, time since exposure, sex, age at exposure and at observation, and possible modfying 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 several large populations with documented therapeutic (e.g., cervical cancer patients), diagnostic (e.g., tuberculosis patients), and occupational (e.g., x-ray technologists) exposures to ionizing radiation. Program members serve on committees advising the government as well as international agencies. Results of studies suggest that (1) susceptibility to radiogenic breast cancer declines with icreasing age at exposure, and children exposed under age 10 are at high risk; a risk at 8-16 rads has been detected; (2) high-dose radiation to the pelvis induces fewer leukemias than other types of exposures; cell-killing appears to play an important role in defining dose-response relationships; (3) repeated exposure to relatively low radiation doses poses some future risk of breast and thyroid cancer, but not lung cancer; (4) children irradiated for benign conditions of the head and neck are at risk of developing thyroid and brain neoplasia; (5) 9% of all thyroid cancers may be attributed to prior childhood irradiation; (6) radiotherapy for childhood cancer was associated with subsequent cancers of the bone, connective tissue and thyroid, but not leukemia; (7) actinomycin-D does not appear to protect against radiation-induced thyroid cancer; (8) radiation of the adrenal glands may lower breast cancer risk; (9) chromosome aberrations following partial-body irradiation persist in circulating lymphocytes for over 30 years.