Abnormal cells in testis multiply and become tumors.
They are relatively uncommon tumors. But all men should prectice scrotal self examination on a regular basis (say x1/month), ideally in the shower. Seek medical help if you feel a hard lump, or one testicle starts to grow much larger than ihe other one. Intraabdominal undescended testes are at cancer
risk even after correction. Prognosis is good.