Cancer that starts in the testicles is called testicular cancer. Testicles have two main functions:

  • They make male hormones (androgens) such as testosterone.
  • They make sperm, the male cells needed to fertilize a female egg cell to start a pregnancy.

More than 90% of cancers of the testicle develop in special cells known as germ cells. These are the cells that make sperm. The two main types of germ cell tumors (GCTs) in men are:

  • Seminomas
  • Non-seminomas, which are made up of embryonal carcinoma, yolk sac carcinoma, choriocarcinoma, and/or teratoma

These two types occur about equally. 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.

Seminomas

Seminomas tend to grow and spread more slowly than non-seminomas. The 2 main subtypes of these tumors are classical (or typical) seminomas and spermatocytic seminomas. Doctors can tell them apart by how they look under the microscope.

Classical seminoma: More than 95% of seminomas are classical. These usually occur in men between 25 and 45.

Spermatocytic seminoma: This rare type of seminoma tends to occur in older men. The average age of men diagnosed with spermatocyticseminoma is about 65. Spermatocytic tumors tend to grow more slowly and are less likely to spread to other parts of the body than classical seminomas.

Some seminomas can increase blood levels of a protein called human chorionic gonadotropin(HCG). HCG can be detected by a simple blood test and is considered a tumor marker for certain types of testicular cancer. It can be used for diagnosis and to check how the patient is responding to treatment.

Non-seminomas

These types of germ cell tumors usually occur in men between their late teens and early 30s. The 4 main types of non-seminoma tumors are:

  • Embryonal carcinoma
  • Yolk sac carcinoma
  • Choriocarcinoma
  • Teratoma

Most tumors are a mix of different types (sometimes with a seminoma component as well), but this doesn’t change the general approach to treatment of most non-seminoma cancers.

Embryonal carcinoma: This type of non-seminoma is present to some degree in about 40% of testicular tumors, but pure embryonal carcinomas occur only 3% to 4% of the time. When seen under a microscope, these tumors can look like tissues of very early embryos. This type of non-seminoma tends to grow rapidly and spread outside the testicle.

Embryonal carcinoma can increase blood levels of a tumor marker protein called alpha-fetoprotein (AFP), as well as human chorionic gonadotropin (HCG).

Yolk sac carcinoma: These tumors are so named because their cells look like the yolk sac of an early human embryo. Other names for this cancer include yolk sac tumor, endodermal sinus tumor, infantile embryonal carcinoma, or orchidoblastoma.

This is the most common form of testicular cancer in children (especially in infants), but pure yolk sac carcinomas (tumors that do not have other types of non-seminoma cells) are rare in adults. When they occur in children, these tumors usually are treated successfully. But they are of more concern when they occur in adults, especially if they are pure. Yolk sac carcinomas respond very well to chemotherapy, even if they have spread.

This type of tumor almost always increases blood levels of AFP (alpha-fetoprotein).

Choriocarcinoma: This is a very rare and aggressive type of testicular cancer in adults. Pure choriocarcinoma is likely to spread rapidly to distant organs of the body, including the lungs, bones, and brain. More often, choriocarcinoma cells are present with other types of non-seminoma cells in a mixed germ cell tumor. These mixed tumors tend to have a somewhat better outlook than pure choriocarcinomas, although the presence of choriocarcinoma is always a worrisome finding.

This type of tumor increases blood levels of HCG (human chorionic gonadotropin).

Teratoma: Teratomas are germ cell tumors with areas that, under a microscope, look like each of the 3 layers of a developing embryo: the endoderm (innermost layer), mesoderm (middle layer), and ectoderm (outer layer).

Pure teratomas of the testicles are rare and do not increase AFP (alpha-fetoprotein) or HCG (human chorionic gonadotropin) levels. More often, teratomas are seen as parts of mixed germ cell tumors.

There are 3 main types of teratomas:

  • Mature teratomas are tumors formed by cells similar to cells of adult tissues. They rarely spread to nearby tissues and distant parts of the body. They can usually be cured with surgery, but some come back (recur) after treatment.
  • Immature teratomas are less well-developed cancers with cells that look like those of an early embryo. This type is more likely than a mature teratoma to grow into (invade) surrounding tissues, to spread (metastasize) outside the testicle, and to come back (recur) years after treatment.
  • Teratomas with somatic type malignancy are very rare cancers. These cancers have some areas that look like mature teratomas but have other areas where the cells have become a type of cancer that normally develops outside the testicle (such as a sarcoma, adenocarcinoma, or even leukemia).

Cancers that start in another organ and then spread to the testicle are called secondary testicular cancers. These are not true testicular cancers – they are named and treated based on where they started.

Lymphoma is the most common secondary testicular cancer. Testicular lymphoma occurs more often than primary testicular tumors in men older than 50. The outlook depends on the type and stage of lymphoma. The usual treatment is surgical removal, followed by radiation and/or chemotherapy.

In boys with acute leukemia, the leukemia cells can sometimes form a tumor in the testicle. Along with chemotherapy to treat the leukemia, this might require treatment with radiation or surgery to remove the testicle.

Cancers of the prostate, lung, skin (melanoma), kidney, and other organs also can spread to the testicles. The prognosis for these cancers tends to be poor because these cancers have usually spread widely to other organs as well. Treatment depends on the specific type of cancer.

In recent years, a lot of progress has been made in treating testicular cancer. Surgical methods have been refined, and doctors know more about the best ways to use chemotherapy and radiation to treat different types of testicular cancer.

After the cancer is diagnosed and staged, your cancer care team will discuss treatment options with you.

Depending on the type and stage of the cancer and other factors, treatment options for testicular cancer can include:

  • Surgery
  • Radiation therapy
  • Chemotherapy (chemo)
  • High-dose chemotherapy and stem cell transplant

In some cases, more than one of type of treatment might be used.

You may have different types of doctors on your treatment team, depending on the stage of your cancer and your treatment options. These doctors may include:

  • An uro-oncosurgeon: a surgeon who specializes in treating diseases of the urinary system and male reproductive system
  • A radiation oncologist: a doctor who treats cancer with radiation therapy
  • A medical oncologist: a doctor who treats cancer with medicines such as chemotherapy