Risk of testicular cancer in men with abnormal semen characteristics: cohort study

Objective To explore the associations between semen characteristics and sub sequent risk of testicular cancer. Design Cohort study Participants 32 442 men who had a semen analysis done at the Sperm Analysis Laboratory in Copenhagen during 1963-95. Main outcome measure Standardised incidence ratios of testicular cancer com pared with total population of Danish men. Results Men in couples with fertility problems were more likely to develop testicular cancer than other men (89 cases, standardised incidence ratio 1. 6; 95% confidence interval 1.3 to 1.9). The risk was relatively constant wi th increasing time between semen analysis and cancer diagnosis. Analysis ac cording to specific semen characteristics showed that low semen concentrati on (standardised incidence ratio 2.3), poor motility of the spermatozoa (2. 5), and high proportion of morphologically abnormal spermatozoa (3.0) were all associated with an increased risk of testicular cancer. The only other cancer group that showed ina eased incidence was "peritoneum and other dige stive organs (six cases; 3.7, 1.3 to 8.0). Of these, two cases were probabl y and two cases were possibly extragonadal germ cell rumours. Conclusions The results point towards the existence of common aetiological factors for low semen quality and testicular cancer. Low semen quality may also be associated with increased incidence of extragonadal germ cell tumou rs.