中国膀胱癌死亡率与紫外线照射的关系

Analysis of the relationship between bladder cancer mortality and ultraviolet irradiation

目的探讨膀胱癌死亡率与紫外线照射的关系，为生态流行病学研究提供实验依据。方法收集整理1990至1992年中国第二次死亡原因调查报告中膀胱癌的死亡资料及各调查地区的经纬度和日平均紫外线照射强度数据，统计学分析膀胱癌死亡率与环境因素的相关性。结果膀胱癌死亡率与紫外线照射强度有明显关系，死亡率随年平均紫外线照射强度增高而降低，日平均紫外线照射强度每增加一个单位，死亡率下降0．56％（P=0．0013）。不同性别和不同地区存在相同的负相关，男性和女性相对危险度分别为0．9949和0．9934（P值分别为0．0161和0．0239），城市和农村地区分别为0．9945和0．9942（P值分别为0．0332和0．0102）。结论紫外线照射可以降低膀胱癌的死亡率，其机制可能与体内维生素D水平增加有关。

Objective To investigate the relationship between bladder cancer and ultraviolet irradiation for providing ecological information on cancer prevention and control. Methods The cancer death data were retrieved from second cancer death survey, 1990-1992, China. The estimated daily cloud-adjusted ambient solar UVB irradiance at 305 nanometers （mW/m^2 ）, was obtained from NASA database the total ozone mapping spectrometer （TOMS） using ArcGIS 9. 1 software to measure the county level average daily irradiance over the whole year. Negitive binomial regression modeling by SAS statistics software was adopted for analysis. Results Mortality of bladder cancer was negitively related with UVB irradiation in both sexes and in different sexes and locations. Adjusted mortality fell by 0. 56% per unit of UVB （rate ra＇do 0. 9944, 95%CI 0. 9911-0. 9977, P=0. 0013）. This downtrend was stronger for female （0.66% per unit of UVB） than for male （0.51%） and stronger in rural areas （0.58G） than in urban areas （0. 55%）. Conclusions Sunshine irradiation might reduce the mortality of bladder cancer probably by increasing the concentration of vitamin D in the body. Further study would be necessary to explain the reaction mechanisam.