Perinatal markers of estrogen exposure and risk of testicular cancer: follow-up of 1,333,873 Danish males born between 1950 and 2002

Objective To examine whether indicators of an increased prenatal estrogen exposure correlate with risk of testicular cancer. Methods This nationwide follow-up study was conducted by linking data on prenatal exposures obtained from medical and birth records for information on incident testicular cancer cases identified from the Danish Cancer Registry. The study population included all boys born between 1950 and 2002 and alive in April 1968 or later with restriction to sons of mothers born after 1935 and alive in April 1968. Results A total of 2,151 incident testicular cancer cases were identified in 29 million person-years at risk. Men born with a high birth weight ([4,150 g) had an increased risk of testicular cancer [incidence rate ratio (IRR) = 1.6 (95% CI: 1.0, 2.4)]. Having a twin sister was associated with reduced risk [IRR = 0.5 (95% CI: 0.2, 1.1)], and the IRR for sons of mothers suffering from preeclampsia indicated a low risk [IRR = 0.6 (95% CI: 0.2, 2.0)], although none of these estimates were statistically significant. Increasing sib order and preterm birth was not associated with decreased risk. Principal conclusions Results provide no strong evidence for the hypothesis.