The incidences of malignant gonadal and extragonadal germ cell tumors in males and females: a population-based study covering over 40 years in Finland

Abstract

Germ cell tumors (GCTs) comprise a heterogeneous group of tumors derived from primordial germ cells. The incidence of malignant testicular GCTs has increased in recent decades, but little is known about possible changes in malignant female GCTs. Population-based data covering all malignant GCTs in both sexes remain limited. All cases of malignant GCTs in 1969-2008 were collected from the Finnish Cancer Registry and their age-adjusted annual incidences calculated. The overall incidence of malignant GCTs was 2.56 per 100,000 person-years in males and 0.34 per 100,000 in females. The incidence of gonadal GCTs increased from 2.27 to 8.36 per 100,000 in males between 15 and 44 years of age. Moreover, the incidence of all histological subtypes of gonadal GCTs increased in males. In females, the only increase was seen in the incidence of ovarian non-dysgerminoma (from 0.07 to 0.29/100,000). The incidence of extragonadal GCTs did not change during the study period, being 0.18 and 0.10 per 100,000 in males and females, respectively. The incidence of gonadal GCTs in males increased significantly during the 40-year study period, whereas in females, no such change was observed. There were significant gender differences regarding the distribution of histological subtypes and patients' ages. However, the incidence of extragonadal GCTs remained low in both sexes. The differences in the incidences of gonadal GCTs derived from the same population suggest that the risk factors of these malignancies differ between the two sexes.