Trends of incidence and age in adults with testicular germ cell tumors: a two-decade multicenter retrospective study

Background Testicular germ cell tumors (GCTs) are the most common type of cancer in adolescent boys and young adult men, but the age at onset has been increasing. However, little is known regarding the incidence and age of patients with testicular GCTs in Japan because the incidence there is low. Methods We retrospectively reviewed the medical records of patients with GCTs in seven hospitals between 2001 and 2021. We compared the incidences of testicular GCTs, ages at onset, pathological types (seminoma or nonseminoma), and clinical stages in patients with GCTs between the periods 2001–2010 and 2011–2021. Results We identified 193 adults (≥20 years of age) with testicular GCTs; their median age was 37 years [interquartile range (IQR), 29–47 years]. Of these patients, 87 (45.1%) were ≥40 years of age at diagnosis. The proportion of patients aged ≥40 years was significantly higher in the period 2011–2021 (54.8%) than in 2001–2010 (30.8%; P=0.001). The incidence of seminoma was significantly higher in the period 2011–2021, but clinical stage did not differ significantly between the two periods. The population-adjusted incidence among patients in their 40s was 3.4-fold higher in 2011–2021 than in 2001–2010. Conclusions The number of patients with GCTs aged ≥40 years was significantly higher in 2011–2021, even in a population-adjusted analysis. Treatment strategies need to be adapted to older testicular germ cell tumor patients.