Trends in incidence of testicular cancer in Norway 1955-1992.

The aim of this study was to explore the incidence of testicular cancer (TC) in Norway, and thereby to increase the understanding of aetiological factors. From 1995 to 1992, a total number of 3927 TC cases were recorded in Norway, of which 51% were seminomas, 45% non-seminomas and 4% other and unspecified types. The age-standardised incidence rate increased from 2.7 to 8.5 per 100,000. The age-specific incidence rate increased in all age groups, but was most marked in the younger population. The significance of birth cohort as a risk factor for development of TC was confirmed. The incidence by birth cohorts from 1916 to 1970 showed an increase by later birth cohorts during the whole period, with the exception of a marked fall for the cohort born during the Second World War. The largest increase occurred after the war. We conclude that environmental factors acting very early in life are of significance in the development of TC.