Seminoma is a kind of testicular germ cell tumor, with seminoma cells as the main component, which may be accompanied by elevated HCG and LDH, but no elevated AFP. Stage III is when the tumor has metastasized to other organs. The higher the stage, the worse the prognosis. The main factor affecting the prognosis is whether there is extra-pulmonary organ metastasis. For treatment of seminoma, radical testicular resection is usually performed, and patients with stage Ia and Ib can be closely followed up; for stage Is patients, retroperitoneal radiotherapy is recommended; for stage IIa and IIb patients, in addition to radical testicular resection, retroperitoneal radiotherapy or chemotherapy is usually performed; for stage IIc and III patients, four cycles of BEP chemotherapy are usually performed. The prognosis for testicular seminoma is generally good, with postoperative follow-up starting every 3 months to prevent local or retroperitoneal recurrence of the tumor.