Extragonadal germ cell tumors are made up of cells that form during the early development of a fetus (unborn baby). In a growing fetus, germ cells typically move from a site near the middle of the body to the ovaries or testes (gonads). There they develop into eggs in females and sperm in males.
When cells that are meant to form sperm or eggs travel to other parts of the body instead, they can form tumors outside the gonads. That's why they are often called extragonadal germ cell tumors. They usually begin in the lungs; the lower back; the back of the abdomen; or the middle of the brain, near the pea-sized pineal gland.
Extragonadal germ cell tumors (EGCTs) are rare. EGCTs are classified as seminomas or nonseminomas (of which there are several subtypes). In children, EGCTs affect boys and girls equally. But in adults, the vast majority of these tumors affect men.
The cells of each type of tumor look different under a microscope. Also, each has a different prognosis and treatment. Seminomas tend to be very responsive to radiation therapy, making that the mainstay for treatment. Chemotherapy is often used to treat nonseminomas, but it may be used to treat seminomas as well.
This article will focus on seminomas and nonseminomas.
Symptoms depend on the location of the tumor:
- Mid-chest. EGCTs here can cause chest pain, breathing problems, a cough, weight loss, nausea and fever. Patients may also have bulging veins on their chest and neck. These tumors are most often diagnosed in men in their 20s.
- Lower back. EGCTs here usually appear as a mass in the lower abdomen or buttocks. They are more commonly diagnosed in infants or young children than in adults. The mass may cause difficulty in walking, urinating or having a bowel movement.
- Back of the abdomen. EGCTs in the back of the abdomen may cause back pain or kidney problems. (The mass can put pressure on the tubes that transport urine from the kidneys to the bladder.) Sometimes, the abdominal mass can be felt during a physical exam.
- Brain (pineal gland). Germ cell tumors can press on parts of the brain and interfere with the flow of fluid around the brain and spinal cord. This can cause:
- memory loss
- lack of energy
- difficulty walking
- inability to look up
- uncontrolled eye movements
- double vision
A child with a tumor that produces hormones may show signs of puberty earlier than normal. Almost all pineal germ cell tumors, which are very rare, occur in people younger than 40.
Because EGCTs are rare, your doctor probably will ask about common medical conditions that could be causing your symptoms. For example, if you have a cough, fever and difficulty breathing, your doctor may suspect a respiratory infection. The true cause of your condition probably won't be known until your doctor orders X-rays or scans of the area where you have symptoms.
Your doctor will examine you, paying special attention to the area where you have symptoms. If you have symptoms of a lower-back tumor, your doctor may do a rectal exam and, in women, a pelvic exam. If you have symptoms of a brain tumor, he or she will do a neurological exam.
Your doctor will order different diagnostic tests depending on the tumor's location:
- Mid-chest. In nearly all cases, a standard chest X-ray can show the tumor's location. A Computed tomography (CT) scan of the chest can reveal the tumor's extent. An abdominal CT can determine whether the tumor has spread to the liver or other sites. To confirm the diagnosis, doctors usually examine a piece of the tumor. It can be removed with a needle or by cutting away a bit of tissue. This is called a biopsy. However, some patients with nonseminomas can be diagnosed through blood tests that look for elevated levels of two substances: alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (beta-hCG).
- Back of the abdomen and lower back. Ultrasound or magnetic resonance imaging (MRI) will be used to assess the size of the tumor. To see if the cancer has spread, your doctor probably will order a bone scan, chest X-ray, CT scan of the lungs, and a bone-marrow biopsy. A biopsy must be done to confirm the diagnosis.
- Brain. Although a CT scan of the head usually will show a tumor in the pineal gland, an MRI provides more information. To make a definitive diagnosis, the tumor is removed surgically and examined in a laboratory.
Because of the association between EGCTs and a rare blood cancer, your doctor may check your blood counts. An evaluation of your bone marrow may also be part of the diagnostic workup.
In most patients, blood tests of the levels of AFP and beta-hCG can help to determine the type of tumor (seminoma or nonseminoma). In people with brain (pineal) tumors, AFP and beta-hCG levels also may be measured in the spinal fluid. The fluid is removed from the spinal cord with a needle. This procedure is called a spinal tap (lumbar puncture).
Unless treated, an EGCT will continue to grow. Depending on its location, the cancer may spread to the lungs, bones (especially the spine), liver or other sites.
There is no way to prevent EGCTs.
Treatment depends on the location and type of tumor. In general, small seminomas are treated with radiation; larger ones are treated with chemotherapy (anticancer drugs) followed by radiation. Nonseminomas almost always are treated with chemotherapy followed by surgery to remove any remaining cancer. Some medical centers also use high-dose chemotherapy with a bone marrow or stem cell transplant.
- Mid-chest. Seminomas usually are treated with high-dose radiation and sometimes with chemotherapy. However, if the seminoma occurs in the chest and there is no evidence of cancer that has originated from the testis, chemotherapy is the mainstay of treatment. Nonseminomas are treated with chemotherapy.
- Back of the abdomen and lower back. Chemotherapy shrinks the tumor before it is removed surgically. If the entire tumor cannot be removed, a second course of chemotherapy may be given, followed by another surgery. If this second round of chemotherapy has not eradicated the tumor, patients may be offered stem cell transplantation.
- Brain. The tumor is removed surgically. Both nonseminomas and seminomas may be treated with radiation. However, because high-dose radiation can damage the brain, some hospitals combine chemotherapy with a lower dose of radiation, especially for nonseminomas.
Because doctors want to determine the best treatment for rare cancers, your doctor may talk with you about enrolling in a clinical trial. Clinical trials study experimental drugs and other new therapies.
In addition to routine xray studies such as CT scans, your physician will follow you with blood tests that can also help determine whether cancer is present and its activity.
Call your doctor if you or your child has any symptoms of an EGCT. Because these tumors are rare, many cancer specialists have limited experience in treating them. If you are diagnosed with one of these tumors, get a second opinion. Seek treatment at a cancer center with staff experienced in treating these tumors.
Survival for people with EGCTs depends on the tumors' location:
- Mid-chest. More than three-quarters of people with seminomas treated with radiation alone survive for many years. Some studies show that survival may increase if chemotherapy is added. The prognosis for nonseminomas is somewhat less favorable.
- Back of the abdomen and lower back. Even for patients with localized cancer, the survival rate is only about 28%. That rate drops greatly if the cancer has spread to other organs.
- Brain. After treatment, the chances of long-term survival are quite good.
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