Testicular cancer.

Testicular cancer is a disease that predominantly affects young and middle aged men. Our data show that incidence rates have recently increased in men aged 15-54 years in all 13 populations examined, irrespective of whether the populations were at high, moderate or low underlying risk. The annual percentage increase in this age group between 1970 and 1985 varied from 1.9% in the West Midlands, UK, to 6.6% in Miyagi, Japan, with a median of 2.7%. Analysis of the data in two separate age bands, 15-34 and 35-54 years, shows that increases are occurring in both subgroups. This, together with analyses by histological category in Denmark and the West Midlands, UK, indicates that both teratomas and seminomas are increasing in incidence. In contrast to the pattern for incidence rates, testicular cancer mortality rates are now declining in all the nine national populations examined. The time from which mortality rates started to decline varies between populations, and in Poland, a reduction was not observed until the 1980-1985 period. This reflects delay in the uptake of effective chemotherapy for the treatment of teratomas. The decline in mortality, against a background of rapidly increasing incidence in most populations, emphasizes the appreciable improvements in prognosis associated with testicular cancer in recent decades. Although the epidemiology of testicular cancer strongly suggests the presence of environmental risk factors that may be controllable, our ignorance about the nature of these factors precludes any strategy of prevention. Early diagnosis and improved treatment will therefore remain a major focus for the control of this cancer. Our ability to treat testicular cancer is thus a major and necessary achievement given the increase in incidence.