Subfertility increases risk of testicular cancer: evidence from population-based semen samples

Objective To further understand the association between semen quality and cancer risk by means of well defined semen parameters. Design Retrospective cohort study. Setting Not applicable. Patient(s) A total of 20,433 men who underwent semen analysis (SA) and a sample of 20,433 fertile control subjects matched by age and birth year. Intervention(s) None. Main Outcome Measure(s) Risk of all cancers as well as site-specific results for prostate cancer, testicular cancer, and melanoma. Result(s) Compared with fertile men, men with SA had an increased risk of testicular cancer (hazard rate [HR] 3.3). When the characterization of infertility was refined using individual semen parameters, we found that oligozoospermic men had an increased risk of cancer compared with fertile control subjects. This association was particularly strong for testicular cancer, with increased risk in men with oligozoospermia based on concentration (HR 11.9) and on sperm count (HR 10.3). Men in the in the lowest quartile of motility (HR 4.1), viability (HR 6.6), morphology (HR 4.2), or total motile count (HR 6.9) had higher risk of testicular cancer compared with fertile men. Men with sperm concentration and count in the 90th percentiles of the distribution (≥178 and ≥579 × 106 /mL, respectively), as well as total motile count, had an increased risk of melanoma (HRs 2.1, 2.7, and 2.0, respectively). We found no differences in cancer risk between azoospermic and fertile men. Conclusion(s) Men with SA had an increased risk of testicular cancer which varied by semen quality. Unlike earlier work, we did not find an association between azoospermia and increased cancer risk.