A new study found interesting and contradictory links between fatherhood and prostate cancer risk. Using a national population-based register to analyze data on Danish men born between 1935 and 1988, Kristian Jorgensen and colleagues from the Statens Serum Institut in Copenhagen, Denmark, identified 3,400 men who developed prostate cancer.

The researchers found that men without children were 16 percent less likely than men with children to have prostate cancer. However, they also found that among fathers, prostate cancer risk gradually reduces as number of children fathered increased. No association was found between prostate cancer risk and child gender, as suggested in some previous studies.

The authors did not find evidence in the analysis for the findings, but suggested that "additional studies are required to identify the underlying biologic, environmental, social and/or behavioral factors that explain the observed differences in prostate cancer risk between men fathering few and those fathering many children."

The study appears in the Jan. 7, 2008, issue of Cancer.