Types of Testicular Cancer

Ninety-five percent of testicular cancers arise from sperm-forming, or germ cells, and are called germinal tumors. The remaining 5 percent are nongerminal tumors. About 40 percent of germinal tumors are categorized as seminomas. Several other types of germinal tumors are referred to collectively as non-seminomas.

These distinctions are important because each type grows and spreads differently, which influences treatment.

Seminomas

Germ cells become malignant at a very early stage in their development. They may be anaplastic, classic (or typical), or spermatocytic, depending on their origin. Eighty-five percent of seminomas are of the classic type. They occur most often in men in their 40s. Anaplastic seminomas are more aggressive and are more likely to metastasize to other parts of the body. Spermatocytic seminomas usually occur in men over 50. The rate of metastasis for this type of cancer is low.

Non-seminomas

Cells, which are more mature and specialized than the germ cells, give rise to non-seminomas. This type of testicular cancer affects men in their mid-30s; the aggressiveness of the disease varies. Twenty to 25 percent of the tumors are embryonal carcinomas, which are aggressive tumors; 25 to 30 percent are teratoma carcinomas, which are also aggressive; yolk-sac tumors, or choriocarcinomas, are extremely rare (about 1 percent of testicular cancers); and some tumors include more than one cell type.

Testicular cancers tend to spread via the spermatic cord and associated blood and lymph vessels into local lymph glands called the retroperitoneal the lymph nodes. Metastases of the right testis are more likely to affect the lymph nodes near the aorta, the major blood vessel leading away from the heart, called the para-aortic lymph nodes. When metastases beyond the lymph nodes occur, they are most likely to arise in the lungs, liver, bone, or brain.