A 23-year-old previously healthy man comes to the office after | USMLE Biochemistry Videos & Books

A 23-year-old previously healthy man comes to the office after noticing a painless, hard mass in the left testis. Scrotal ultrasound shows a solid testicular mass, and CT scan of the abdomen and pelvis shows left paraaortic lymphadenopathy. Left orchidectomy is performed and postoperative histopathology reveals seminoma of the testis. External beam radiotherapy is administered to the paraaortic metastatic area . Several weeks later, the retroperitonea1 nodes are observed to have markedly decreased in size.