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Germ Cell Tumors

What Are Germ Cell Tumors?

Germ cells are the cells in a developing fetus that form the reproductive organs in both boys and girls. They are the cells that produce sperm in males and eggs in females. These cells normally develop along what's called the "midline" of a fetus (umbilical cord) ) before finally settling into place.

Germ cells that grow abnormally, can become tumors . and often develop in the ovaries or testes. Sometimes, because the germ cells have travelled along the midline during development, they can settle in other places, along their way to the reproductive organs outside of the gonads. 

The most common sites for germ cell tumors outside of the reproductive organs are along the midline in the mediastinum (part of the chest between the breastplate and spine), tailbone, abdomen, and pelvis. Some also might develop in the middle part of the brain.

What Are the Types of Germ Cell Tumors?

Like tumors that develop in other places in the body, germ cell tumors can be benign (not cancerous) or malignant (cancerous). There are several different types of germ cell tumors. The most common germ cell tumors include:

Teratomas. These tumors are benign, but can become malignant. Teratomas are the most common type of germ cell tumor to develop in extragonadal (not in the ovary or testes) areas.. Teratomas usually can only be treated with surgery because chemotherapy doesn’t work in a benign tumor.

Germinomas. These malignant tumors are sometimes called dysgerminomas when they develop in the ovary, or seminomas when they develop in the testes. They may also develop in the middle part of the brain.. 

Yolk sac tumor (also called endodermal sinus tumor). These tumors are malignant . They most commonly develop in the ovaries, testes, or tailbone.

Embryonal carcinoma. The cells making up this malignant tumor usually develop along with other types of malignant cells. These tumors develop most often in the testicle of an adolescent boy, but can spread (metastasize) to other places in the body.

Choriocarcinoma. This malignant tumor usually develops in the placenta during pregnancy and can affect both the mother and child.

What Causes Germ Cell Tumors?

The cause of most germ cell tumors is not well known. Doctors do know that certain medical conditions can make a child more likely to develop a germ cell tumor. These include birth defects that involve the central nervous system, genitals, urinary tract, and spine; as well as certain genetic conditions that result in a missing or extra sex chromosomes.

Boys with undescended testicles (testes that remain up inside the pelvis) also appear to be at increased risk of developing a germ cell tumor.

What Are the Signs & Symptoms of Germ Cell Tumors?

Early on, a child with a benign or malignant germ cell tumor might have few symptoms or none at all. As the tumor grows, a mass (lump) may be felt or cause symptoms due to the tumor pressing against other organs in the body.

When the tumor is located in certain places, other symptoms may be noticed. These include: constipation or trouble holding urine if the tumor is in the pelvis, leg weakness if the tumor is pressing on the nerves at the bottom of the spine, or a testicle that is abnormal in shape or size.

How Are Germ Cell Tumors Diagnosed?

A doctor who suspects that a child has a tumor will do a thorough examination in addition to these tests:

Imaging studies. These might include a CT scan, MRI, X-ray, ultrasound, and a bone scan. These tests are helpful in figuring out the size and location of the tumor and can help determine if cancer has spread (metastasized) to other parts of the body.

Biopsy. A biopsy is when a piece of tissue is removed from the body for further examination in the pathology lab. This closer look by the pathologist helps cancer doctors make a diagnosis and choose the right treatment. A biopsy often can be done through a laparascope using a small incision and a camera to guide the doctor's movements). Other times open surgery may be needed because of the location of the tumor.

Blood tests. Tests such as a  blood count, kidney and , and tests to check the minerals in the blood can give important information about how well the liver and other organs are working. Alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (β-HCG) tests are called tumor markers. These tests check for higher than normal levels of these proteins in the body. This can suggest the presence of a germ cell tumor. The same tests are used to check how the treatment is working. These markers are also helpful once a patient has completed treatment to determine if the tumor has come back. 

If the doctor suspects the tumor is related to an underlying genetic condition, certain genetic tests also might be done.

How Are Germ Cell Tumors Treated?

Children with benign germ cell tumors will undergo surgery to remove the tumor. Those with malignant tumors will receive treatment after a process called staging.

Staging is a classification system that helps doctors figure out how far the cancer has progressed. It takes into account things like:

  • the size of the tumor (or tumors)
  • how deep the tumor is located in an organ
  • whether the tumor has metastasized to nearby or distant lymph nodes or organs (such as the lung or brain)

This information, in addition to a child's age and overall health, helps doctors develop treatment plans that may include the following options, in combination or alone:

Surgery. Children with malignant tumors may have surgery to remove as many of the cancerous cells as possible. 

Radiation therapy. This treatment uses high-energy radiation from X-rays, gamma rays, or fast-moving subatomic particles (called particle or proton beam therapy) to target and destroy cancer cells. Radiation is not usually needed to treat germ cell tumors because they are typically very sensitive to chemotherapy.

Chemotherapy. Chemotherapy works to treat cancer throughout the body when there is a mass of cancer cells that can be seen on a scan or felt on an exam. Chemotherapy is also the most important therapy to treat microscopic (very tiny) cells that may be hiding in other parts of the body but can’t be seen on a scan or felt on exam. It is common for such microscopic cells to exist. Often, several chemotherapy drugs are combined to attack the cancer cells in different ways. 

Looking Ahead

The stress of having a child who is being treated for any type of tumor can be overwhelming. And being told that a child has cancer can be a difficult and scary experience.

To find support for you or your child, talk to your child's doctor or a hospital social worker. Many resources are available to help you get through this difficult time.