Germ-cell tumors
Germ-cell tumors (GCTs) are a type of tumor that arises from germ cells, which are the reproductive cells in the body formed during embryonic development. These tumors can be either benign or malignant and are most commonly found in the ovaries and testes. Major risk factors for developing GCTs include congenital disabilities, such as Kriptorchidism in males, and genetic conditions like Klinefelter syndrome. The most prevalent types of germ-cell tumors include seminomas, teratomas, and embryonal carcinomas, with testicular germ-cell tumors being notably common among young males.
Symptoms often manifest as noticeable masses or swelling, particularly in the testicles, and may include abnormal shapes or sizes. Diagnosis typically involves imaging studies and blood tests to check for tumor markers, enabling healthcare providers to determine the appropriate treatment. Treatment usually consists of surgical removal of the tumor, followed by chemotherapy or radiation if the tumor is malignant. Prognosis varies based on factors such as tumor size, location, and whether the cancer has spread, with an overall cure rate of 82 to 90%. Continuous follow-up care is vital, especially for children diagnosed with GCTs, due to potential side effects and the risk of secondary malignancies that can occur after treatment.
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Subject Terms
Germ-cell tumors
ALSO KNOWN AS: Seminoma, nonseminoma, embryonal cell cancer, teratoma, endothermal signal tumor, mature and immature teratomas
RELATED CONDITIONS: Testicular cancer, ovarian cancer
DEFINITION: Germ-cell tumors (GCTs) are tumors of cancerous or noncancerous cells that arise from germ cells during embryonic development.
Risk factors: The only confirmed germ-cell tumor risk involves congenital disabilities. Male infants with undescended testes (cryptorchidism) are approximately three times more likely to develop germ-cell tumors than male infants with customarily descended testes. Children with the genetic disease Klinefelter syndrome are also at an increased risk for germ-cell tumors.
Etiology and the disease process: Germ cells develop in the embryo and become the cells that make up the reproductive system in men and women. After development, these germ cells follow a midline path through the body and descend into the pelvis as ovarian cells or the scrotal sac as testicular cells. Most ovarian tumors and testicular tumors are of germ-cell origin. 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.
Types of germ-cell tumors include germinomas (seminomas when found in testes, dysgerminomas in ovaries), teratomas, endodermal sinus tumors, embryonal carcinomas, and choriocarcinomas.
Extragonadal germ-cell tumors form from developing sperm or egg cells that travel from the gonads to other body parts. They can be benign (noncancerous) or malignant (cancerous). Benign extragonadal germ-cell tumors are called benign teratomas. These are often very large and more common than malignant extragonadal germ-cell tumors. Teratomas are further classified as mature (lining resembles skin) and immature (cancer cells look like cells from a developing fetus).
Incidence: Around nine thousand gonadal germ cell tumors are diagnosed yearly in the United States, primarily in young adults. Ovarian and testicular germ cell tumors account for an estimated 14 percent of all cancers diagnosed in adolescents between fifteen and nineteen. Young children rarely develop germ cell tumors. Ovarian germ cell tumors are the most common germ cell tumors, occurring primarily in girls between ten and fourteen. Most male adolescents are diagnosed with testicular germ-cell tumors after puberty. These tumors are usually malignant, making up 90 percent of testicular cancer diagnoses. Extragonadal germ cell tumors comprise 40 to 50 percent of germ cell tumors. Incidence among different ethnic groups varies depending on age and tumor site.
Symptoms: Patients with germ-cell tumors usually complain of a tumor, swelling, or mass that can be felt or seen. With testicular germ-cell tumors, patients may notice that testicles have an abnormal shape or irregularity in size. Additional symptoms can include elevated levels of alpha-fetoprotein (AFP), beta-human chorionic gonadotropin (beta-hCG), and lactate dehydrogenase (LDH). Constipation, incontinence, and leg weakness can occur if the tumor is compressing structures in the sacrum (a segment of the vertebral column that forms the top part of the pelvis). Malignant extragonadal germ-cell tumors may cause symptoms such as chest pain or breathing problems.
Screening and diagnosis: Diagnostic procedures for germ-cell tumors may include a of the tumor; blood tests, including a complete blood count (CBC) to determine the size, number, and maturity of different blood cells within the blood; and multiple imaging studies, such as computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, and X-ray. Scientists have identified a tumor marker in the blood called lactate dehydrogenase isoenzyme 1 (LD1). Increased levels of this enzyme indicate seminoma in more than 60 percent of patients.
The staging of the disease depends on its development in the ovary or testis.
Treatment and therapy: Treatments for germ-cell tumors are determined by the patient’s age, overall health, medical history, and extent of the disease. The treatment plan also relies heavily on whether the tumor is extragonadal or malignant. Treatments for germ-cell tumors are similar to those for ovarian tumors and testicular tumors, usually involving surgery to remove the tumors. If cells are malignant, patients may undergo chemotherapy or radiation to reduce the risk of recurrence of cancerous cells. In some cases, patients will require a bone marrow transplant or hormone replacement therapy.
Prognosis, prevention, and outcomes: Prognosis dramatically depends on the extent of the disease, the size and location of the tumor, whether the cancer has spread, and the age and overall health of the patient. The average cure rate of all cases of germ-cell tumors is 82 to 90 percent. Prompt medical attention and aggressive therapy are essential for the best prognosis. Continuous follow-up care is necessary for children 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 discovered to improve treatment and decrease side effects.
Bibliography
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Frazier, A. Lindsay, and James F. Amatruda, eds. Pediatric Germ Cell Tumors: Biology, Treatment, Survivorship. Springer, 2014.
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