Childhood Cancer Risk in the Siblings and Cousins of Men with Poor Semen Quality

Purpose: Poor semen quality is associated with reduced somatic health and increased cancer risk. Infertility and cancer are increasingly being linked by epidemiologists and basic scientists. We sought to identify semen parameters associated with an increased childhood cancer risk in the family members of subfertile men.

Materials and methods: We performed a retrospective cohort study in men from the SHARE (Subfertility Heath and Assisted Reproduction) study who underwent semen analysis between 1994 and 2011. We used fertile population controls from the Utah Population Data Base. Our primary outcome was the risk of any childhood (18 years or younger) cancer in the siblings and cousins of men who underwent semen analysis compared to fertile, age matched controls. Cox proportional hazard regression models were used to test the association between semen quality and childhood cancer incidence.

Results: We selected 10,511 men with complete semen analysis and an equal number of fertile controls. These men had a total of 63,891 siblings and 327,753 cousins. A total of 170 and 958 childhood cancers were identified in siblings and cousins, respectively. The 3 most common cancers diagnosed in siblings were acute lymphoblastic leukemia in 37, brain cancer in 35 and Hodgkin lymphoma in 15. Oligozoospermia was associated with a twofold increased risk of any childhood cancer and a threefold increased risk of acute lymphoblastic leukemia in the siblings of subfertile men compared to fertile controls (HR 2.09, 95% CI 1.18-3.69 vs HR 3.07, 95% CI 1.11-8.46).

Conclusions: Siblings of men with oligozoospermia are at increased risk for any-site cancer and acute lymphoblastic leukemia. This suggests a shared genetic/epigenetic insult or an environmental exposure that merits further investigation.