Overall, the cohort members had an increased risk of testicular cancer and of cancers of the peritoneum and other digestive organs (table ). Risk of other types of cancer was not increased in the cohort. Eighty nine men developed testicular cancer, giving a standardised incidence ratio of 1.6 (95% confidence interval 1.3 to 1.9). Of these 89 men, 50 had seminomas (standardised incidence ratio 1.5, 1.1 to 1.9), 37 had non-seminomas (1.8, 1.2 to 2.4), and two were unspecified. For cancer of the peritoneum and other digestive organs the standardised incidence ratio was 3.7 (1.3 to 8.0) based on six observed cases. The standardised incidence ratio for cancers of all other sites combined was 1.0 (0.9 to 1.1).
Standardised incidence ratios and 95% confidence intervals for different cancers in cohort of 32 442 men having sperm analysis in Copenhagen, 1963-95
Table shows the standardised incidence ratios for testicular cancer stratified by time between first semen analysis and cancer diagnosis. The highest risk of testicular cancer was in the first two years after the first semen analysis (standardised incidence ratio 1.8). The risk was 1.5-1.6 for two to 11 years after the first semen analysis and 1.3 for more than 11 years since first semen analysis. The trend in the standardised incidence ratios over the four periods of follow up was not significant (P=0.46).
Standardised incidence ratios and 95% confidence intervals for testicular cancer, stratified by time since semen analysis
Table shows the standardised incidence ratios of testicular cancer, stratified by measures of semen quality. In univariate analyses, low semen concentration, poor semen mobility, and a high proportion of abnormal spermatozoa were all associated with increased standardised incidence ratios, whereas the groups with normal semen characteristics had standardised incidence ratios closer to unity. The azoospermic men who had fathered children before semen analysis showed lower risk of testicular cancer than azoospermic men without children (standardised incidence ratio 2.0 v 5.3). Men who were not azoospermic but who had sperm concentrations of 20 million/ml or lower had a higher risk of testicular cancer than men with concentrations above 20 million/ml (standardised incidence ratio 2.3 v 1.1).
Standardised incidence ratios and 95% confidence intervals for testicular cancer according to semen characteristics
The univariate, separate, and joint effects of the three semen quality measures were analysed in the subgroup of 29
177 men who had some spermatozoa in the semen sample (table ). The separate effect of low concentration on the risk of testicular cancer was roughly the same as the univariate effect (standardised incidence ratio 2.1 and 2.3, respectively). Of 10
509 men with low semen concentration, 9187 had low concentration as the only abnormal characteristic. Very few men had poor motility only or a high proportion of abnormal spermatozoa only, and no case of testicular cancer was observed in these groups. We therefore could not identify a separate effect of poor motility or of having a high proportion of abnormal spermatozoa. However, the risk of testicular cancer increased with increasing number of subfertility measures present. The standardised incidence ratio was 1.9 for one subfertility measure, 2.7 for two measures, and 9.3 for all three subfertility measures.
Separate and joint effects of three semen quality measures on risk of testicular cancer among 29 177 men with some spermatozoa in semen
Table gives the details of the six cases of cancer in the peritoneum and other digestive organs. Case 1 may have had a testicular cancer before his leukaemia, which probably was treatment induced. An extragonadal germ cell tumour is also possible for case 2, who had increased concentrations of tumour markers. The notifications suggest that cases 3 and 5 had extragonadal germ cell tumours. Cases 4 and 6 seemed unlikely to have had extragonadal germ cell cancers.
Evaluation of the six cases of cancers of peritoneum and other digestive organs based on notification forms received from Danish Cancer Registry