Germ cell tumors in children and adolescents in Finland: trends over 1969-2008.
Malignant germ cell tumors (GCTs) are a heterogeneous group of neoplasms putatively originating from the primordial germ cell. In adults, an increasing incidence of GCTs, particularly testicular tumors, has been reported in recent decades. However, population-based evidence in children and adolescents remains limited. We investigated the incidence of malignant GCTs diagnosed in childhood or adolescence, using population-based nationwide data from Finland. We obtained information from the Finnish Cancer Registry on all malignant GCTs registered in 1969-2008 in children or adolescents aged 0-19 years. Data on tumor location, histology, stage, and survival were collected. Age-standardized incidence and survival rates were calculated. A total of 334 cases of malignant GCT were identified. Their proportion among all malignant tumors among 0- to 19-year-olds increased from 3 to 9.7% in boys with time, but remained stable in girls (3%). The overall incidence rate was 0.6 per 100,000 (0.8 in boys and 0.4 in girls), and differed significantly between the age groups. A significant increase in the incidence of testicular GCTs was seen in boys in the age group of 15-19 years. Although malignant GCTs are rare, their relative frequency in children and adolescents has increased during recent decades, the change being mainly due to an increasing frequency of the testicular tumors among teenagers. The causes of the increase remain unknown, but environmental exposures are likely to be involved.