目的验证第三系地质因素是胃癌高发的因素。方法把胃癌死亡率分布图与地质图进行对照，计算各省第三系地层出露区占其总面积的百分比及冲积平原土壤中第三系地层物质的百分比，再与胃癌死亡率进行相关分析。结果可见胃癌高死亡率的地区分布在大面积出露的第三系地质区，少数分布在第三系地层冲积平原区。各省第三系地层出露面积的百分比与胃癌死亡率呈正相关（ｔ＝０４５６５，Ｐ＜００１）。此外，冲积平原土壤中第三系地层物质的含量与男性胃癌死亡率有显著相关（ｒ＝０９８７７，Ｐ＜００５）。结论与胃癌高发相关的致癌物存在于出露的第三系地层或来源于这一地区的沉积物之中 Objective To verify that tertiary geological factors are the factors that contribute to the high incidence of gastric cancer. Methods The gastric cancer death rate map was compared with the geological map. The percentage of the total area of ​​exposed areas of Tertiary strata in the provinces and the percentage of Tertiary strata material in alluvial plains were calculated. The results showed that areas with high mortality of gastric cancer were distributed in areas exposed to a large area of ​​Tertiary, and a few in the alluvial plain area of ​​the Tertiary. The percentage of exposed area in the tertiary strata of each province was positively correlated with the mortality rate of gastric cancer (t=04565, P<001). In addition, the content of Tertiary strata in the alluvial plain soil was significantly associated with male gastric cancer mortality (r=09877, P<005). Conclusion Carcinogens associated with high incidence of gastric cancer are present in exposed Tertiary strata or sediments originating from this area