STUDIES OF RADIATION-INDUCED CANCER

癌症风险在日本原子弹幸存者和患者中进行了研究 医疗照射、从事放射性职业的工作人员和 暴露在自然发生的辐射中 生物化学方法是 纳入研究，以帮助确定基本机制。 程序 成员在向政府和国际社会提供咨询的委员会任职， 社. 研究结果表明：（1）室内氡暴露量较少， 比以前认为的危险;（2）乳腺癌的放射治疗 会轻微增加对侧乳房患癌的风险，但不会 在45岁以上接受治疗的妇女中;（3）放射性乳腺癌的风险 癌症发病率随着接触的年龄的增长而下降， 首次怀孕发生在20岁之前的妇女比未生育妇女 或初次怀孕年龄较晚的妇女; (4)放射治疗 乳腺癌会增加患白血病的风险，尤其是在 使用烷基化剂;（5）低剂量放射治疗子宫 出血诱发的白血病比高剂量放疗治疗的白血病要多得多。 宫颈癌或子宫癌;（6）高剂量放射性碘 治疗不会明显增加白血病的风险，这表明 延长剂量可降低风险;（7）儿童期放射治疗 癌症大大增加甲状腺癌的风险;（8）放射治疗 对于双侧视网膜母细胞瘤， 表明遗传易感性在辐射风险中的重要性; (9)在原子弹幸存者和铀矿工人中， 癌症倾向于小细胞亚型。

Cancer risk is studied among Japanese A-bomb survivors, patients medically irradiated, workers in radiation occupations, and persons exposed to naturally occurring radiations. Biochemical approaches are incorporated into studies to help define basic mechanisms. Program members serve on committees advising the government and international agencies. Results of studies suggest that (1) indoor exposure to radon appears less hazardous than previously believed; (2) radiotherapy for breast cancer increases the risk of cancer in the opposite breast slightly, but not among women treated over age 45; (3) the risk of radiation-induced breast cancer declines with increasing age at exposure, and is lower among women whose first pregnancy occurred before age 20 than among nulliparous women or women with a late age at first pregnancy; (4) radiotherapy for breast cancer increases the risk of leukemia, especially in combination with alkylating agents; (5) low-dose radiotherapy to treat uterine bleeding induces many more leukemias than high-dose radiotherapy to treat cancers of the cervix or uterus; (6) high-dose radioactive iodine treatments do not appreciably increase the risk of leukemia, suggesting that protraction of dose reduces risk; (7) radiotherapy for childhood cancers greatly increases the risk of thyroid cancer; (8) radiotherapy for bilateral retinoblastoma greatly increases the risk of osteosarcoma, indicating the importance of a genetic susceptibility in radiation risk; (9) in both A-bomb survivors and uranium miners, radiation-induced lung cancers tend to be of the small-cell subtype.