Researchers in Denmark -- which has one of the highest testicular cancer incidence rates in the world -- found 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.

Dr. Charlotte Myrup of Statens Serum Institut in Copenhagen, Denmark, and colleagues collected data on 2.1 million men who lived in Denmark from 1968 to 2003 -- including 344,444 immigrants to Denmark and 56,189 men born in Denmark to immigrant parents.

Overall, 4,216 cases of testicular cancers were reported -- 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 study, published in the Journal of the National Cancer Institute, found the difference in testicular cancer rates among men born to foreign parents inside Denmark, compared with those immigrating to Denmark as children or adults, pointed to the possibility of environmental influences in utero.