Cancer is a group of many related diseases. All cancers begin in cells
, the body's basic unit of life. Cells make up tissues, and tissues make up the organs of the body.
Normally, cells grow and divide to form new cells as the body needs them. When cells grow old and die, new cells take their place. Sometimes this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor
Tumors can be benign or malignant.
Benign tumors are not cancer.
Usually, doctors can remove them. Cells from benign tumors do not spread to other parts of the body. In most cases, benign tumors do not come back after they are removed. Most important, benign tumors are rarely a threat to life.
Malignant tumors are cancer.
They are generally more serious. Cancer cells can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and enter the bloodstream or the lymphatic system. That is how cancer cells spread from the original (primary
) tumor to form new tumors in other organs. The spread of cancer is called metastasis
Germ Cell Tumors
“Extragonadal” means outside of the gonads
(sex organs). When cells that are meant to form sperm in the testicles or eggs in the ovaries travel to other parts of the body, they may grow into extragonadal germ cell tumors. These tumors may begin to grow anywhere in the body but usually begin in organs such as the pineal gland in the brain, in the mediastinum, or in the abdomen.
Extragonadal germ cell tumors can be benign or malignant. Benign extragonadal germ cell tumors are called benign teratomas
. These are more common than malignant extragonadal germ cell tumors and often are very large.
Malignant extragonadal germ cell tumors are divided into two types, nonseminoma
Nonseminomas tend to grow and spread more quickly than seminomas. They usually are large and cause symptoms. If untreated, malignant extragonadal germ cell tumors may spread to the lungs, lymph nodes, bones, liver, or other parts of the body.