Risk of testicular cancer in subfertile men: case-control study

ObjectiveTo evaluate the association between subfertility in men and the subsequent risk of testicular cancer.DesignPopulation based case-control study.SettingThe Danish population.ParticipantsCases were identified in the Danish Cancer Registry; controls were randomly selected from the Danish population with the computerised Danish Central Population Register. Men were interviewed by telephone; 514 men with cancer and 720 controls participated.ResultsA reduced risk of testicular cancer was associated with paternity (relative risk 0.63; 95% confidence interval 0.47 to 0.85). In men who before the diagnosis of testicular cancer had a lower number of children than expected on the basis of their age, the relative risk was 1.98 (1.43 to 2.75). There was no corresponding protective effect associated with a higher number of children than expected. The associations were similar for seminoma and non-seminoma and were not influenced by adjustment for potential confounding factors.ConclusionThese data are consistent with the hypothesis that male subfertility and testicular cancer share important aetiological factors.

Key messages

• The incidence of testicular cancer has increased in the past 50 years, and there is some evidence to suggest that sperm quality has decreased in the same period
• It has been hypothesised that common aetiological factors may exist for testicular cancer and for male subfertility
• The association between male subfertility and subsequent risk of testicular cancer is strong and consistent with the hypothesis of a common aetiology
• The association is similar for seminoma and non-seminoma, and it persists when several potentially confounding factors are taken into account