Germ Cell Tumors Health Article

Definition

Germ cell tumors are tumors that begin in cells that, in a developing fetus, become sperm or egg cells. Because of the way a baby develops in the womb, these kinds of tumors are found in the ovaries and testes, and in other sites along the midline of the body, such as the brain, the center of the chest, and the center back wall of the abdominal cavity. They can also be found in the center parts of the pelvis, cervix, and uterus, in the vagina or prostate, in the oral or nasal cavities, or on the lips. These tumors are usually discovered either during the first few years of life, or shortly after puberty (when an increase in hormone levels may initiate cancer formation).

Description

Germ cell tumors are a diverse group of tumors that all begin in germ cells, the cells in the developing fetus that become sperm or egg cells. Incidence in the United States is 2-3 cases/million live births. They can occur in the ovaries or testes or outside the reproductive organs in many other locations along the middle of the body. Some are very malignant and some are almost always benign; most require surgery, although some kinds are also treated with additional radiation or chemotherapy. Some typically appear in infancy, others are more common in adolescents. The treatment and prognosis will depend on the kinds of tissues present in the tumor and on the location.

Germ cell tumors are divided into two types: germinomas, which contain only immature germ cells; and embryonic tumors, which contain some cells that have started to develop into other tissues (as would happen in normal development of a fetus). Embryonic types of tumor commonly include endodermal sinus tumors, embryonal carcinoma, choriocarcinoma and teratoma. Gonadoblastoma and polyembryoma are rare types of embryonic germ cell tumors. Many tumors are mixed, containing more than one cell type.

Generally, any kind of germ cell tumor can appear at any germ cell tumor site, although some types are significantly more common at some locations. For example, about 40% of all germ cell tumors are teratomas in the area of the tailbone, which are typically diagnosed in the first month or two of life. Germinomas and endodermal sinus tumors are most common in the ovaries. Embryonal carcinomas are most common in the testes, usually mixed with endodermal sinus tumors or choriocarcinoma.

Demographics

Like other features of this diverse group of tumors, demographics of this cancer vary with the site and type. The peak in incidence of germ cell tumors during the first few years of life is primarily due to the high numbers of teratomas in the tailbone area, which are about 4 times more common in girls than in boys. The second peak, however, in adolescents reflects a significant number of testicular cancers in teenage and young adult males. Other common childhood germ cell tumors are tumors of the abdomen, vagina and testicles in infants, brain tumors in childhood, and ovarian tumors in early teens. Adult germ cell tumors in adults are usually in the testes or ovaries. Germ cell tumors are found in all populations of the world in approximately equal numbers.

Causes and symptoms

The causes of germ cell tumors are not well understood, although events at puberty—probably increases in certain hormone level—are thought to play a role in tumors of the ovaries and testicles that occur in adolescents or early teens. Some germ cell tumors have a high percentage of certain genetic sequences, thought to be a possible cause of those types of cancers, while some have a high frequency of abnormal chromosome numbers. Some types of germ cell tumors do tend to run in families. Since germ cell tumors are made up of several different types of cancers, there are probably at least several different causes.

The most common symptom of germ cell tumors is a mass along the midline of the body. This mass may be accompanied by abdominal pain or bloating. Other possible symptoms include:

• constipation
• enuresis (involuntary discharge of urine)
• early entry into puberty
• vaginal bleeding
• late onset of menstruation
• menstrual problems
• excessive hair growth
• weakness in legs
• need to urinate often
• shortness of breath, other breathing problems
• diabetes
• hormonal abnormalities
• stunted growth
• headaches or vision problems