March 9, 2011 — A prospective trial of Finnish men born in 3 different periods since 1979 shows a progressive decrease in the quality and quantity of sperm that coincides with a rise in the incidence of testicular cancer, investigators say in an article published online March 2 in the International Journal of Andrology. "These simultaneous and rapidly occurring adverse trends suggest that the underlying causes are environmental and, as such, preventable," they write.
Finnish men must undergo a medical examination when they reach 18 or 19 years of age, and their records can be considered representative of the general population, senior author Jorma Toppari, MD, PhD, from the University of Turku, Finland, and colleagues explain in their article.
The investigators invited all men having these examinations between 1998 and 2006 to participate in the study. In addition to the examination, the volunteers donated a semen sample and completed a questionnaire asking about their lifestyle and overall health status. They were paid 40 to 50 euros for their time. A total of 858 men, or 13.4% of the invited population, enrolled: 338 men who were examined in 1998 to 1999, 382 who were examined in 2001 to 2003, and 138 who were examined in 2006. The birth years of these cohorts were 1979 to 1981, 1982 to 1983, and 1987, respectively, so all men had a mean age of 19 years at the time they were studied.
Semen quality was assessed by having the same technician analyze semen volume and sperm motility and concentration in all the samples throughout the duration of the study. Another investigator analyzed sperm morphology at the end of the study period.
Semen volume did not differ significantly among the different cohorts. Variations in sperm concentration, total sperm count, and numbers of morphologically normal sperm are shown in the table.
Table.
The investigators also found that between 1954 and 2008, the annual incidence of testicular cancer rose more in Turku, which is located in southwestern Finland, than it did in the rest of the country. Between 1979 and 1983, the cumulative annual incidence of testicular cancer was fewer than 5/100,000 in Finland as a whole, but about 8/100,000 in Turku; in 1989 to 1993, incidence had risen only slightly nationwide but was at just under 10/100,000 in Turku. Incidence in Turku has increased dramatically since then compared with a slower increase throughout Finland.
All in all, the authors write, "the incidence rate is 8-10 times higher for Finns born around 1980 compared with men born around 1950. Furthermore, testicular germ-cell cancers in adults arise from carcinoma-in-situ cells, which are of fetal origin. Thus, the increase in the testicular cancer incidences should be interpreted as a birth cohort effect." They cautioned that these findings should be considered preliminary, given the relatively small number of men involved.
The data on sperm motility should be viewed with caution, as such analyses tend to be highly subjective, the authors warn. Also, the participation rate was low compared with the number of men contacted, but the cohorts still were considered to be representative of young men living in the Turku area at the time the analyses were done.
These preliminary data showing deterioration in semen quality among recent birth cohorts of Finnish men and the rising incidence of testicular cancer, particularly among men from Turku, may be related to an increased incidence of testicular dysgenesis syndrome recently seen in Finnish men, the authors speculate. The rapid rate of these changes points to possible environmental influences, such as exposure to pesticides and other chemicals.
This study was supported by grants from the European Union, the Academy of Finland, Turku University Hospital Funds, and the Sigrid Juselius Foundation. One of the coauthors received financial support from the Danish Agency for Science, Technology, and Innovation. The other authors have disclosed no relevant financial relationships.
Int J Androl. Published online March 2, 2011. Abstract
Finnish men must undergo a medical examination when they reach 18 or 19 years of age, and their records can be considered representative of the general population, senior author Jorma Toppari, MD, PhD, from the University of Turku, Finland, and colleagues explain in their article.
The investigators invited all men having these examinations between 1998 and 2006 to participate in the study. In addition to the examination, the volunteers donated a semen sample and completed a questionnaire asking about their lifestyle and overall health status. They were paid 40 to 50 euros for their time. A total of 858 men, or 13.4% of the invited population, enrolled: 338 men who were examined in 1998 to 1999, 382 who were examined in 2001 to 2003, and 138 who were examined in 2006. The birth years of these cohorts were 1979 to 1981, 1982 to 1983, and 1987, respectively, so all men had a mean age of 19 years at the time they were studied.
Semen quality was assessed by having the same technician analyze semen volume and sperm motility and concentration in all the samples throughout the duration of the study. Another investigator analyzed sperm morphology at the end of the study period.
Semen volume did not differ significantly among the different cohorts. Variations in sperm concentration, total sperm count, and numbers of morphologically normal sperm are shown in the table.
Table.
| Birth Year | ||||
| 1979 - 1981 | 1982 - 1983 | 1987 | P Value (2006 Values Compared With the Other 2 Periods) | |
| Median sperm concentration (million/mL) | 67 (95% confidence interval [CI], 57 - 80) | 60 (95% CI, 51 - 71) | 48 (95% CI, 39-60) | .04 |
| Total sperm count (millions) | 227 (95% CI, 189 - 272) | 202 (95% CI, 170 - 240) | 165 (95% CI, 132 - 207) | .07 |
| Total number of morphologically normal spermatozoa (millions) | 18 (95% CI, 14 - 23) | 15 (95% CI, 12 - 19) | 11 (95% CI, 8 - 15) | .02 |
| Percent motile sperm, median | 65 (95% CI, 63 - 66) | 74 (95% CI, 72 - 75) | 73 (95% CI, 71 - 74) | <.0005 |
All in all, the authors write, "the incidence rate is 8-10 times higher for Finns born around 1980 compared with men born around 1950. Furthermore, testicular germ-cell cancers in adults arise from carcinoma-in-situ cells, which are of fetal origin. Thus, the increase in the testicular cancer incidences should be interpreted as a birth cohort effect." They cautioned that these findings should be considered preliminary, given the relatively small number of men involved.
The data on sperm motility should be viewed with caution, as such analyses tend to be highly subjective, the authors warn. Also, the participation rate was low compared with the number of men contacted, but the cohorts still were considered to be representative of young men living in the Turku area at the time the analyses were done.
These preliminary data showing deterioration in semen quality among recent birth cohorts of Finnish men and the rising incidence of testicular cancer, particularly among men from Turku, may be related to an increased incidence of testicular dysgenesis syndrome recently seen in Finnish men, the authors speculate. The rapid rate of these changes points to possible environmental influences, such as exposure to pesticides and other chemicals.
This study was supported by grants from the European Union, the Academy of Finland, Turku University Hospital Funds, and the Sigrid Juselius Foundation. One of the coauthors received financial support from the Danish Agency for Science, Technology, and Innovation. The other authors have disclosed no relevant financial relationships.
Int J Androl. Published online March 2, 2011. Abstract
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