Testicular cancer is a disease in which malignant cells form in the tissues of one or both testicles. Almost all testicular cancers start in the germ cells. The two main types of testicular germ cell tumors are seminomas and nonseminomas.

Testicular cancer is the most common cancer in men 20 to 35 years old. Health history can affect the risk of developing testicular cancer. Possible signs of testicular cancer include swelling or discomfort in the scrotum.

The prognosis (chance of recovery) and treatment options depend on the stage of the cancer (whether it is in or near the testicle or has spread to other places in the body, and blood levels of AFP, β-hCG, and LDH), type of cancer, size of the tumor and number and size of retroperitoneal lymph nodes.