Children's Hospital Colorado

Testicular Germ Cell Tumors (Seminoma and Non-seminoma)

What is a testicular germ cell tumor?

A testicular germ cell tumor is a form of testicular cancer. Germ cells in males are the cells that make sperm. More than 90% of testicular cancers start in the germ cells. There are two types of germ cells: seminomas and non-seminomas. Depending on which type of germ cell the cancer starts from, they form differently.

Seminomas and non-seminomas germ cell tumors (GCT)

Seminomas GCT tend to grow and spread more slowly than non-seminomas. Many testicular cancers contain both seminoma and non-seminoma cells. These mixed germ cell tumors are treated as non-seminomas because they grow and spread like non-seminomas.

What causes testicular germ cell tumors in children?

Doctors have not identified a clear cause for most cases of germ cell tumors in children. An increased risk of germ cell tumors has been associated with certain inherited diseases and genetic syndromes. These inherited diseases are also often associated with malformations of the central nervous system, genitourinary tract and lower spine.

Boys with cryptorchidism or undescended testicles also have an increased risk of developing testicular germ cell tumors. Cryptorchidism, however, can occur on its own and is also related to other genetic syndromes.

Who gets testicular germ cell tumors?

Testicular germ cell tumors are of course limited to boys. But germ cell tumors in general can occur in both boys and girls, although they are rare. Germ cell tumors account for about 2% to 4% of all cancers in children and adolescents younger than the age of 20.