The incidence and mortality rates of esophageal cancer, including cancer of the gastriccardia, are high in the areas of North China, where in some counties it is ranked as the firstcause in the total death rate. An epidemiological survey of esophageal cancer has beencarried out in the period of 1969 to 1971 covering 181 counties and cities with a totalpopulation of nearly fifty million. Area with high mortality rate of esophageal cancerwas located in the southern parts of the Taihang Mountains on the borders of Honan,Shansi, and Hopei provinces. From this area extending out like irregular concentric belts,the mortality rates decreased gradually. The highest age-sex adjusted mortality ratereached 139.80/100,000 and the lowest rate was 1.43/100,000, with an average mortality rateof 37.39/100,000. The ratio of male to female patients was on the average of 1.6 to 1.The higher the mortality rate of a locality the lesser was the difference in its sex ratio.Over 60% of the total mortality rate was in the age groups ranging from 50 to 69. Thedifference in the age groups for areas of highest and lowest mortality rates was about 10years. In counties with a high incidence of the esophageal cancer there were also a greaternumber of people suffering from epithelial dysplasia of the esophagus. The average age-sex adjusted incidence rate of esophageal cancer of Linhsien county(1959-1970) was 108.56/100,000, and the mortality rate was 99.76/100,000. The trendsof mortality rates showed little tendency to change during the past 30 years. The ratioof esophageal cancer to cancer of the gastric cardia was 3 to 1. Most cases of cancer werelocated at the level of mid and lower third of the esophagus. 150 specimens of pharyngo-esophageal cancer in domestic fowls were obtained fromLinhsien. A comparative study showed that in areas of high incidence of esophageal canceramong human beings, cancer among chickens was also common. The result indicated thatthere must be a close relationship between the disease and geographical environment. Preliminary clinical and experimental studies were aso carried out on etiological fac-tors and associated conditions, pathogenesis and histopathology of esophageal cancer.Trace elements in the soil and drinking water, nitrosamines, secondary amines, nitrite andnitrate contents in food items, and fungus contamination in food were analysed for com-parative values in high and low incidence areas. Trials of prophylactic measures in experi-mental animals and in selected groups of high risk persons discovered during mass screeningby cytological examination were studied on the spot.
