Germ cells are cells that migrate into the ovaries and testicles during normal embryonic development to become reproductive cells that produce either eggs in female embryos or sperm in male embryos. If these cells don’t migrate to the proper location, or divide and grow improperly, they may form either benign (non-cancerous) or malignant (cancerous) tumors in different parts of the body.
These tumors are rare in children under the age of 15, but they are the most common solid tumors in adolescents, age 15 to 19.
In addition to being classified as malignant or benign, germ cell tumors are also classified based on cell structure and where they form in the body.
Gonadal germ cell tumors form in a child’s testes or ovaries, otherwise known as “gonads,” and account for the majority of all germ cell tumors. If germ cells don’t move to the gonads during fetus development, they can end up in abnormal locations and form tumors in other parts of the body, such as the abdomen, chest, neck, head, and brain. These extragonadal germ cell tumors generally occur in early childhood.
There are three main types of germ cell tumors: teratomas, seminomas, and non-seminomas.
- Teratomas are masses that can be made up of immature and mature cells, and may contain different types of tissue, including hair, muscle, and bone. These types of tumors, often containing cysts, are benign.
- By contrast, seminomas and non-seminomas are germ cell tumors that are malignant. These two types of tumors vary in terms of the maturation of cell: seminomas have not matured at all, whereas non-seminomas resemble the early structures of fetal or placental growth.
- A germ cell tumormany contain both seminoma and non-seminoma cells as well as teratoma. This is known as a mixed germ cell tumor.
The cause of most germ cell tumors is unknown and symptoms may resemble those of other more common conditions or medical problems. Although each child may experience germ cell tumor symptoms differently, some common symptoms include a swelling or mass on the body that can be seen or felt; constipation; shortness of breath, if the tumor is located in the chest; and elevated levels of certain proteins secreted by the tumors into the blood.
Treatment for germ cell tumors depends on several factors, including the child’s age, overall health, medical history, and the type, size, and location of the tumor. Treatment plans typically consist of surgery, chemotherapy, or both.
Surgical removal of the entire tumor is usually enough to cure a mature or immature teratomas—as well as seminomatous/nonseminomatous germ cell tumors—if the tumor has not spread elsewhere, according to Lindsay Frazier, MD, a pediatric oncologist in the Solid Tumor Center at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center. However, given that these tumors can arise in a myriad of locations in the body, the surgery can be quite complicated. Moreover, the tumors can impinge upon the other organs in the body.
To minimize long-term effects of surgery, Frazier recommends seeking an experienced surgeon to perform the operation.
Chemotherapy is needed to cure seminomatous/non-seminatous GCT that have spread beyond the original location of the tumor. Chemotherapy is often used before surgery to help shrink the tumor, making it easier to remove. Radiation is rarely, if ever, used to treat germ cell tumors.
Finally, the majority of children with rare conditions, such as germ cell tumors, voluntarily opt to participate in research studies that evaluate new treatment approaches. Findings from these types of clinical trials have increased survival rates significantly in the last several decades for children with germ cell tumors. Overall, the survival rate is close to 85 percent for most children with germ cell tumors.