广东阳江高本底地区居民癌症及其相关因素研究主要结果

目的综合分析阳江高本底地区居民癌症及其相关因素研究结果,讨论该研究的学术意义.方法合并分析19972～1986年和1987～1998年癌症死亡观察资料,同时分析混淆因素、人群可比性、人体免疫功能研究等资料.结果对环境和宿主的可能致癌与致突变因素进行分类研究表明两地区基本符合"齐同对比"原则,两人群是可比的;高本底地区居民白细胞介素-2分泌细胞(IL-2SC)水平明显高于对照;根据1979～1998年125079人共累积观察1992 940人年的癌症死亡率分析资料,整个高本底地区全癌死亡的相对危险为1.00(95%CI,0.89～1.14),与对照地区差异没有显著性,不同剂量组及其部位别的癌症死亡相对危险均未发现与剂量呈一致性变化趋势;全部实体癌的超额相对危险系数(ERR/Sv),在整个高本底地区估算为-0.06(95%CI,-0.60～0.67).结论未发现高本底地区居民癌症死亡增加,也未发现高本底地区有辐射相关的部位别癌症死亡的增加,相反,存在高本底辐射刺激免疫功能增强的趋势.

Major results of the study on cancer mortality and its related factors among inhabitants in the high background radiation area (HBRA) of Yangjiang,Guangdong

Objective To analyze the major results of study on cancer mortality and its related factors among inhabitants in the high background radiation area (HBRA) of Yangjiang, and discuss its values on effects of low dose radiation. Methods The data of cancer mortality in the period of 1979 - 1986 and those of 1987 - 1998 were combined by record linkage. The data of confounding factors , comparability and immune competence from cohort members were analyzed. Results The results of data on carcinogenic and mu-tagenic factors showed that they were similar in the two areas. The frequency of PBL-IL2SC was significantly increased in the subjects from HBRA compared to those similar"between HBRA and control area (CA)". During the period of 1979 - 1998, the follow-up for 125 079 subjects accumulated 1 992 940 person-years and identified 12 444 deaths, including 1 202 cancer deaths. The RR of mortality of all cancers was 1.00(95% CI, 0.89 - 1.14) showing no difference between HBRA and CA. The RRs of all cancers in low, intermediate and high dose groups in HBRA did not show statistical difference from the control area. The comparison of RRs of site-specific cancer mortality among difference dose groups and the dose-response analysis of site-specific cancer mortality related to cumulative individual lifetime dose did not give any monotonic trend. The ERR per Sv for all solid cancers associated with cumulative individual lifetime dose was estimated to be - 0.06(95% CI, - 0.60 - 0.67). Conclusion The mortality of all cancers showed no statistical difference between HBRA and CA, and any radiation-related excess of site-specific cancer in HBRA could not be found. On the contrary, there was a tendency that the immune function was increased after exposure to low level radiation for a long time.