 Germ Cell Tumors
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Germ cells tumors are malignant (cancerous) or non-malignant (benign, non-cancerous) tumors that are composed primarily of germ cells. Germ cells are the cells that develop in the embryo (fetus, or unborn baby) and become the cells that make up the reproductive system in males and females. These germ cells follow a midline path through the body after development and descend into the pelvis as ovarian cells or into the scrotal sac as testicular cells. Most ovarian tumors and testicular tumors are of germ cell origin. The ovaries and testes are called gonads.
Tumor sites outside the gonad are called extragonadal sites. The tumors also occur along the midline path and can be found in the head, chest, abdomen, pelvis, and sacrococcygeal (lower back) area. Germ cell tumors represent about 3 percent of all childhood cancers.
Germ cell tumors are rare, as only about 2.4 children in one million develop one of these tumors in a given year. Germ cell tumors account for about 4 percent of all cancers in children and adolescents under the age of 20 years.
Germ cell tumors can spread (metastasize) to other parts of the body. The most common sites for metastasis are the lungs, liver, lymph nodes, and central nervous system. Rarely, germ cell tumors can spread to the bone, bone marrow, and other organs.
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The cause of germ cell tumors is not completely understood. A number of inherited defects have also been associated with an increased risk of developing germ cell tumors including the central nervous system and genitourinary tract malformations, and major malformations of the lower spine. Specifically, males with cryptorchidism (failure of the testes to descend into the scrotal sac) have an increased risk of developing testicular germ cell tumors. Cryptorchidism can occur alone, however, and is also present in some genetic syndromes.
In addition, cells from testicular germ cell tumors can have structural chromosome abnormalities involving chromosome #12, which may explain the uncontrolled cell growth and tumor formation. Some genetic syndromes caused by extra or missing sex chromosomes can cause incomplete or abnormal development of the reproductive system.
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The following are the most common symptoms of germ cell tumors. However, each child may experience symptoms differently. Symptoms vary depending on the size and location of the tumor. Symptoms may include:
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- a tumor, swelling, or mass that can be felt or seen
- elevated levels of alpha-fetoprotein (AFP)
- elevated levels of beta-human chorionic gonadotropin (B-HCG)
- constipation, incontinence, and leg weakness, if the tumor is in the sacrum (a segment of
- the vertebral column that forms the top part of the pelvis) compressing structures
- abnormal shape, or irregularity in, testicular size
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The symptoms of germ cell tumors may resemble other conditions or medical problems. Always consult your child's physician for a diagnosis.
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In addition to a complete medical history and physical examination, diagnostic procedures for germ cell tumors may include:
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- biopsy - a sample of tissue removed from the tumor and examined under a microscope
- complete blood count (CBC) - a measurement of size, number, and maturity of different blood cells in a specific volume of blood
- additional blood tests - may include blood chemistries, evaluation of liver and kidney functions, and genetic studies
- multiple imaging studies, including:
- computerized tomography scan (also called a CT or CAT scan) - a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.
- magnetic resonance imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body
- x-ray - a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film
- ultrasound (also called sonography) - a diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels.
- bone scans - pictures or x-rays taken of the bone after a dye has been injected that is absorbed by bone tissue. These are used to detect tumors and bone abnormalities.
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Diagnosis of germ cell tumors depends on the types of cells involved. The most common types of germ cell tumors include:
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- teratomas - Teratomas contain cells from the three germ layers: ectoderm, mesoderm, and endoderm. Teratomas can be malignant or benign, depending on the maturity and other types of cells that may be involved.
Sacrococcygeal (tail bone, or distal end of spinal column) teratomas are the most common germ cell tumors found in childhood. Because these sacrococcygeal tumors are often visible from the outside of the body, diagnosis is made early and treatment and/or surgery are initiated early, making the prognosis for this type of germ cell tumor very favorable. In the newborn, the most common congenital tumor is a sacrococcygeal teratoma.
Treatment for sacrococcygeal teratoma may begin before a baby is born. When diagnosed early in gestation and when of considerable size, these tumors may result in birth defects or fetal death. When this occurs later in pregnancy, fetal intervention in carefully selected cases can be used to remove most of the tumor. In these circumstances, Caesarean delivery may be the best choice.
The preferable treatment of a sacrococcygeal teratoma is complete removal before the baby is born, which includes removal of the coccyx. Depending on the development of the tumor's cells, no further treatment may be needed, or your child's physician may determine that additional chemotherapy may be necessary.
Teratomas may also occur at other germ cell sites including the ovary, testicle, and in such unusual sites as the neck, stomach, and retroperitoneum. Tumors found in the neck may be particularly challenging in the neonatal period because of a location that distorts and obstructs the airway. Surgical and other treatment may be needed before the baby is born. Caesarean delivery with special precautions for the baby's airway is also recommended when these tumor have been identified before birth.
- germinomas - Germinomas are malignant germ cell tumors. Germinomas are also termed dysgerminoma when located in the ovaries; and seminoma when located in the testes. Among children, germinoma, or dysgerminoma, occurs most frequently in the ovary of a pre-pubescent or adolescent female. Dysgerminoma is the most common malignant ovarian germ cell tumor seen in children and adolescents.
- endodermal sinus tumor or yolk sac tumors - Endodermal sinus tumor or yolk sac tumors are germ cell tumors that are most often malignant, but may also be benign. These tumors are most commonly found in the ovary, testes, and sacrococcygeal areas (tail bone, or distal end of spinal column). When found in the ovaries and testes, they are often very aggressive, malignant, and can spread rapidly through the lymphatic system and other organs in the body. Yolk sac tumors are the most common malignant testicular and ovarian tumors in children. Most yolk sac tumors will require surgery and chemotherapy, regardless of stage or presence of metastasis, because of the aggressive nature and recurrence of the disease.
- choriocarcinoma - Choriocarcinoma is a very rare, but often malignant germ cell tumor that arises from the cells in the chorion layer of the placenta (during pregnancy, a blood-rich structure through which the fetus takes in oxygen, food, and other substances while getting rid of waste products). These cells may form a tumor in the placental cells during pregnancy and spread (metastasize) to the infant and mother. When the tumor develops during pregnancy, it is called gestational choriocarcinoma. Gestational choriocarcinoma most often occurs in pregnant females that are 15 to19 years of age. If a non-pregnant young child develops choriocarcinoma from the chorion cells that originated from the placenta that are still in the body, the term used is non-gestational choriocarcinoma.
- embryonal carcinoma - Embryonal carcinoma cells are malignant cells that are usually mixed with other types of germ cell tumors. They occur most often in the testes. These types of cells have the ability to spread to other parts of the body. When these cells are mixed with an otherwise benign type of tumor (mature teratoma), the presence of embryonal carcinoma cells will cause it to become malignant (cancerous).
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Many germ cell tumors have multiple types of cells involved. The diagnosis, treatment, and prognosis are based on the most malignant of the cells present and the majority type of cells that are present.
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Specific treatment for germ cell tumors will be determined by your child's physician based on:
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- your child's age, overall health, and medical history
- extent of the disease
- your child's tolerance for specific medications, procedures, or therapies
- how your child's physician expects the disease to progress
- your opinion or preference
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Treatment may include (alone or in combination):
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- surgery - biopsy and surgical removal of tumors or involved organs, performed by a surgeon
- chemotherapy - a drug treatment that works by interfering with the cancer cell's ability to grow or reproduce. Different groups of drugs work in different ways to fight cancer cells and shrink tumors. Chemotherapy may be used alone for some types of cancer or in conjunction with other therapy such as radiation or surgery. Often, a combination of chemotherapy drugs is used to fight a specific cancer. Certain chemotherapy drugs may be given in a specific order depending on the type of cancer it is being used to treat. While chemotherapy can be quite effective in treating certain cancers, the agents do not differentiate normal healthy cells from cancer cells. Because of this, there can be many adverse side effects during treatment. Being able to anticipate these side effects can help the care team, parents, and child prepare, and, in some cases, prevent these symptoms from occurring, if possible.
Chemotherapy is systemic treatment, meaning it is introduced to the bloodstream and travels throughout the body to kill cancer cells. Chemotherapy can be given:
- as an injection into the muscle or fat tissue
- intravenously (directly to the bloodstream; also called IV)
- intrathecally - chemotherapy given directly into the spinal column with a needle
- radiation therapy - using high-energy rays (radiation) from a specialized machine to damage or kill cancer cells and shrink tumors
- stem cell transplant - a treatment involving stem cells, a specific type of cell from which all blood cells develop. Stem cells develop into red blood cells to carry oxygen, white blood cells to fight disease and infection, and platelets to aid in blood clotting. Transplantation of normal stem cells from another person is used to help restore normal blood production in patients whose own ability to make any or all of these blood cells has been compromised by cancer, intensive cancer treatment, or other types of damage or abnormality. The use of cells from another individual is called allogeneic transplantation. Stem cells collected form patients themselves prior to intensive treatment can also be used to supplement the recovery of the patient's own cells after particularly aggressive course of chemotherapy or radiation therapy. The use of a patient's own cells is referred to as autologous transplantation.
Stem cell transplantation and the treatment needed to manage its effects are complex. Your physician will give you more detailed information on what to expect.
- hormonal replacement (if necessary)
- supportive care - any type of treatment to prevent and treat infections, side effects of treatments, and complications, and to keep your child comfortable during treatment
- continuous follow-up care - a schedule of follow-up care determined by your child's physician and other members of your care team to monitor ongoing response to treatment and possible late effects of treatment
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Prognosis greatly depends on:
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- the extent of the disease.
- the size and location of the tumor.
- presence or absence of metastasis.
- the tumor's response to therapy.
- the age and overall health of your child.
- your child's tolerance of specific medications, procedures, or therapies.
- new developments in treatment.
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As with any cancer, prognosis and long-term survival can vary greatly from individual to individual. Prompt medical attention and aggressive therapy are important for the best prognosis. Continuous follow-up care is essential for a child diagnosed with a germ cell tumor. Side effects of radiation and chemotherapy, as well as second malignancies, can occur in survivors of germ cell tumors. New methods are continually being discovered to improve treatment and to decrease side effects.
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Children's Hospital and Dana-Farber Cancer Institute are conducting numerous research studies that will help clinicians better understand and treat germ cell tumors. Two national studies on improving treatment of germ cell tumors are currently taking place.
In addition, the Dana-Farber/Children's Transplant Program is one of only eight institutions around the country that are investigating the use of umbilical cord transplantation. Also under study is a novel method for preventing graft versus host disease, a serious complication that occurs when transplanted cells do not recognize the tissues and organs of the recipient's body and react against the recipient's tissue. The result of this treatment approach, if it continues to be as successful, will be that the degree of match between donor and the recipient will not need to be particularly close, greatly increasing the pool of potential donors for each patient. This could also eliminate the need for long-term drug therapy traditionally needed to treat graft versus host disease.
Other types of treatment currently being studied include:
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- angiogenesis inhibitors - substances that may be able to prevent the growth of tumors by blocking the formation of new blood vessels that feed the tumors
- biological therapies - a wide range of substances that may be able to involve the body's own immune system to fight cancer or lessen harmful side effects of some treatments
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