What Are Germ Cell Tumors?

If germ cells start to grow out of control, they can form germ cell tumors.

Germ cells are the cells that make sperm and eggs. They are part of our reproductive system.

These cells start forming while the fetus is still growing in the mother's womb. They migrate toward the site where the child's sex glands - the testicles or ovaries - will form. These glands are also called the gonads.

In most cases, childhood germ cell tumors form in the gonads. But some germ cells do not make it as far as the gonads when they migrate. Instead they stop somewhere else in the body.

Germ cell tumors can form in other places such as near the gonads, in the belly, in the space between the breastbone and spine (mediastinum) and the brain. Germ cell tumors outside the gonads are called extragonadal.

Germ cell tumors can be cancer ( malignant ) or not cancer ( benign ).

Most are not cancer. Benign germ cell tumors can still cause health problems, often because they are large and press on other structures. They require treatment.

Germ cell tumors that are cancer include:

  • Yolk sac tumor
  • Choriocarcinoma
  • Seminoma or germinoma

Germ Cell Tumors in Children

Young children, older children and adults can all get germ cell tumors. Germ cell tumors in children at any age are rare.

Only about 1% of children who have cancer before age 15 have germ cell tumors. Doctors do not know what causes germ cell tumors.

Germ Cell Tumor Stages

Young children, older children and adults can all get germ cell tumors. Germ cell tumors in children at any age are rare.

Children who have a germ cell tumor are considered to be at one of these stages:

Stage 1 germ cell tumors

Doctors were able to remove the whole tumor through surgery, and tumor markers do not suggest any more tumor activity.

Stage 2 germ cell tumors

After doctors remove the tumor, they know or suspect some tumor cells were left behind. Tumor markers may suggest the tumor is still active.

Stage 3 germ cell tumors

Doctors can still see parts of the tumor in the child's body after treatment. Also, there are tumor cells in the lymph nodes .

Stage 4 germ cell tumors

Doctors find tumor cells have spread to other sites in the body outside the area near the tumor.

Germ Cell Tumors at Seattle Children's

At Children's, our doctors and other members of your child's team have worked with many children with germ cell tumors. It's important to work with doctors who have experience treating this less common type of cancer. We can offer the latest treatments for your child.

Read more about cancer programs and services at Children's.