dos Santos Silva I, Swerdlow A J
Department of Epidemiology and Population Sciences, London School of Hygiene and Tropical Medicine, UK.
Br J Cancer. 1993 Feb;67(2):330-40. doi: 10.1038/bjc.1993.61.
Thyroid cancer incidence has been increasing in many countries, whereas mortality has been falling due to better survival. Radiation is the best-established risk factor and there has been concern that recent rises in incidence might be related to fallout radiation from atmospheric nuclear weapon tests. We examined thyroid cancer time trends and geographical distribution in England and Wales and possible interpretations of these. During 1962-84, there were significant increases in incidence (P < 0.001) in each sex at ages under 45. Cohort analysis by single year of birth showed an overall increase in incidence risks in women aged 0-44 born since 1920, with a sudden rise in risk for the birth years 1952-55 followed by a lower risk for the more recent cohorts. In men, there was an overall increase in risk at ages 0-44 in successive birth cohorts, but the pattern was irregular. In each sex, the risk in persons aged 45 and over decreased slightly in successive generations. Geographically, highest incidence risks were in countries in North and Mid Wales, in which the risk was almost twice that in the rest of the country. This pattern was present only at ages 45 and over and was most clear in rural areas. The peak of thyroid cancer risk in women born in 1952-55 is consistent with a carcinogenic effect of fallout radiation, since these women were children in the late 1950s and early 1960s when fallout radiation was greatest in England and Wales. The focus of high thyroid cancer risks in Wales was in areas with high levels of fallout radiation. However, thyroid cancer risks in Wales were not high for more recent cohorts (the ones who were exposed to fallout early in life), and a focus on high risk of benign thyroid diseases was present in Wales well before nuclear weapons existed. The distributions of these benign thyroid diseases, or of factors causing them, seem more likely than fallout to explain the high risk areas for thyroid cancer in the country.
在许多国家，甲状腺癌的发病率一直在上升，而由于生存率提高，死亡率一直在下降。辐射是已明确的最重要风险因素，人们担心近期发病率的上升可能与大气层核武器试验产生的沉降辐射有关。我们研究了英格兰和威尔士甲状腺癌的时间趋势和地理分布及其可能的解释。在1962年至1984年期间，45岁以下各年龄段的男女发病率均显著上升（P < 0.001）。按出生年份逐年进行的队列分析显示，自1920年以来出生的0至44岁女性的发病风险总体上升，1952年至1955年出生年份的风险突然上升，随后较近期队列的风险较低。在男性中，0至44岁连续出生队列的风险总体上升，但模式不规则。在各性别中，45岁及以上人群的风险在连续几代人中略有下降。在地理上，北威尔士和中威尔士的发病率风险最高，其风险几乎是该国其他地区的两倍。这种模式仅出现在45岁及以上人群中，在农村地区最为明显。1952年至1955年出生的女性甲状腺癌风险峰值与沉降辐射的致癌作用一致，因为这些女性在20世纪50年代末和60年代初是儿童，当时英格兰和威尔士的沉降辐射最大。威尔士甲状腺癌高风险的集中地区是沉降辐射水平高的地区。然而，威尔士近期队列（早年接触沉降辐射的人群）的甲状腺癌风险并不高，而且在核武器出现之前，威尔士就存在良性甲状腺疾病高风险的情况。这些良性甲状腺疾病或其致病因素的分布似乎比沉降辐射更有可能解释该国甲状腺癌的高风险地区。
