A type of testicular cancer that begins in specialized sex cells called germ cells. These germ cell cancers tend to develop fairly early in life, usually occurring in men who are between their late teens and early 40s. Germ cell tumors that do not contain any elements of a cell type called seminoma are broadly classified as nonseminomas.

Types of Nonseminomas

Nonseminomas include embryonal carcinoma, teratoma, choriocarcinoma, and yolk sac carcinoma. Most nonseminomas have more than one cell type and are known as mixed germ cell tumors; treatment of them is the same. Because all nonseminoma germ cell cancers are treated the same way, the exact type of nonseminoma is not important. The cell type of these tumors is important for estimating the risk of cancer cell spread and the patient’s response to chemotherapy.

Embryonal Carcinoma

The embryonal cell type is most common in this type of nonseminoma germ cell cancer. This type is found in about 40 percent of testicular tumors. Pure embryonal carcinomas occur in only 3 to 4 percent of patients. Seen under a microscope, these tumors can resemble tissues of very early embryos, with a diffuse pattern of disorganized and irregular, small rounded cells that do not have specific organization into organlike structures. This type of nonseminoma is more likely to grow rapidly and spread outside the testicle.

Yolk Sac Carcinomas

Yolk sac tumors are named for the resemblance of their cells to the yolk sac of an early human embryo. Other names for these cancers include endodermal sinus tumors, infantile embryonal carcinomas, and orchidoblastomas. Yolk sac carcinoma is the most common form of testicular cancer in children and is usually successfully treated in this age group.

When yolk sac tumors develop in adults, however, they are more dangerous, especially if they are pure (that is, they do not contain other types of nonseminoma cells), although they still respond very well to chemotherapy if they have spread. This type of tumor releases a protein known as alpha-fetoprotein (AFP), whose presence can help confirm the diagnosis.


Choriocarcinomas are very rare and aggressive testicular cancers that occur in adults and often spread rapidly to distant organs of the body, including the lungs, bone, and brain. Pure choriocarcinoma does not often occur in the testicles. More often, choriocarcinoma cells are present with other types of nonseminoma cells in a mixed germ cell tumor. This type of tumor is classically associated with the production of a protein called human chorionic gonadotropin (hCG).


Teratomas are germ cell tumors that have areas that, when viewed under the microscope, resemble each of the three layers of a developing embryo. The three main types are mature teratoma, immature teratoma, and teratoma with malignant transformation.

Mature teratomas

These tumors are formed by cells similar to cells of adult tissues and rarely spread to nearby tissues or distant areas of the body. Although a mature teratoma rarely spreads, sometimes deposits of mature teratoma are found in other parts of the body after chemotherapy is finished. Experts believe that these deposits represent elements of a tumor that are left behind after chemotherapy; they can usually be cured by surgical removal after chemotherapy.

Immature teratomas

These less well-developed cancers have cells that resemble those of an early embryo and may spread to other organs. Unlike mature teratomas, this type has a greater potential to invade and occasionally to metastasize, and it is this type that sometimes recurs years after treatment.

Teratomas with malignant transformation

These very rare cancers contain some areas that resemble mature teratomas and other areas that resemble types of cancers that develop outside the testicle, in tissues such as muscles, glands of the lungs or intestines, or the brain.


After removal of the testicle with radical orchibctomy, the stage of the tumor is then determined to decide appropriate therapy. Nonseminomas can be treated with additional surgery, chemotherapy, or surveillance. Standard therapy for patients with widespread disease would generally be considered to be four chemotherapy courses of bleomycin, etoposide, and Platinol (cisplatin) (BEP). Those patients who still have traces of a tumor remaining after chemotherapy should then have surgery to remove remaining cancerous tissue. Patients with nonseminomatous extragonadal germ cell tumors who experience relapse after front-line chemotherapy generally have a poor prognosis with a poor response to future chemotherapy regimens, including autologous bone marrow transplantation. These tumors are much more resistant than seminomas to the effects of radiation treatment.

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