To understand the role of genetic factors in the occurrence of esophageal cancer (EC) Methods A genetic epidemiological survey of 132?039 subjects, one tenth of the whole population of Yangquan city, Shanxi Province in Northern China, was conducted in 1994 A total of 228 families with at least one newly occurring EC patient in each family were matched with equal number of control families for a 1∶1 case control study Results The heritability of esophageal cancer among first degree relatives was 52 6%, that among second degree relatives was 31 2%, and the weighted average heritability was 49 2% The segregation ratio was 0 176±0 033, significantly less than 0 25, suggesting a multifactorial inheritance or decreased penetrance of a major locus EC patients in families did not fit the binominal distribution, suggesting evidently familial aggregation The relative risks among the first degree relatives were 10 49 for males, 7 69 for females, and 9 17 for combined data The attributive risks among first degree relatives were 62 13/100?000 for males, 99 94/100?000 for females and 75 15/100?000 for combined data All of these figures were higher than 40 17/100?000, the average of general population of the city Conclusion Genetic factors play an important role in the pathogenesis of esophageal cancer in this area To understand the role of genetic factors in the occurrence of esophageal cancer (EC) Methods A genetic epidemiological survey of 132? 039 subjects, one tenth of the whole population of Yangquan city, Shanxi Province in Northern China, was conducted in 1994 A total of 228 families with at least one newly created EC patient in each family were matched with equal number of control families for a 1: 1 case control study Results The heritability of esophageal cancer among first degree relatives was 52 6%, that among second degree relatives was 31 2%, and the weighted average heritability was 49 2% The segregation ratio was 0 176 ± 0 033, significantly less than 0 25, suggesting a multifactorial inheritance or less penetrance of a major locus EC patients in families did not fit the binominal distribution , suggesting evidently familial aggregation The relative risks among the first degree relatives were 10 49 for males, 7 69 for females, and 9 17 for combined data The attributive risks among first degree relatives were 62 13/100? 000 for males, 99 94/100? 000 for females and 75 15/100? 000 for combined data All of these figures were higher than 40 17/100? 000, the average of general population of the city Conclusion Genetic factors play an important role in the pathogenesis of esophageal cancer in this area