In France, the estimated number of new cases of seminoma testicular germ cell tumors in 2018 was 1,650 [1]. The distribution of histological types varies with age, with seminomatous germ cell tumors accounting for 70% of cases in men over 50, whereas they represent less than 40% in men under 30. Key points: A cancer primarily affecting young men, with an excellent prognosis and a 5-year net standardized survival rate of 97% for diagnoses made between 2010 and 2015; 5-year net survival varies little with age at diagnosis (100% at age 30 and 97% at age 60); Little change over the past 30 years for this cancer, which has been treated with curative intent since the 1990s.