The risk of testicular cancer was significantly lower among first-generation immigrants to Denmark, compared with men born in Denmark to immigrant parents and Danish men with Danish parents, according to a study published online December 25 in the Journal of the National Cancer Institute. This suggests that early exposure to environmental factors may influence the development of the disease.
The incidence of testicular cancer varies considerably worldwide, but the cause of these differences is unknown. Denmark has one of the highest testicular cancer incidence rates in the world.
To assess the impact of genes and the environment on testicular cancer development, Charlotte Myrup, M.D., of Statens Serum Institut in Copenhagen, Denmark, and colleagues compared the incidence of testicular cancer among first- and second- generation immigrants to Denmark and residents of Danish ancestry. They collected data on 2.1 million men who lived in Denmark between 1968 and 2003, which included 344,444 immigrants to Denmark and 56,189 men born in Denmark to immigrant parents.
Overall, 4,216 cases of testicular cancers were reported among this group, 166 cases among first-generation immigrants and 13 cases among second-generation immigrants. The relative risk of testicular cancer was 63 percent lower among first-generation immigrants, but there was no statistically significant difference in risk among second-generation immigrants, compared with men of Danish ancestry.
“The difference in testicular cancer rates among men born to foreign parents inside Denmark compared with those immigrating to Denmark as children or adults point to the possibility of environmental influences in utero,” the authors write.
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